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How to stop condensation on corrugated plastic?
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Lieutenant Scott
Feb 14, 2012, 2:03:04 PM2/14/12
to
I have a shed with a corrugated plastic roof. I get absurd amounts of water condensing under it, which drips onto the contents of the shed.
Is there a way (without spending a fortune) to stop this or to collect the water in some way?
--
http://petersparrots.com
http://petersphotos.com
The three most common expressions (or famous last words) in aviation are:
"Why is it doing that?", "Where the hell are we?", and "Oh Shit!"
Is there a way (without spending a fortune) to stop this or to collect the water in some way?
--
http://petersparrots.com
http://petersphotos.com
The three most common expressions (or famous last words) in aviation are:
"Why is it doing that?", "Where the hell are we?", and "Oh Shit!"
David WE Roberts
Feb 14, 2012, 2:05:55 PM2/14/12
to
"Lieutenant Scott" <n...@spam.com> wrote in message
news:op.v9om7e2dytk5n5@i7-940...
>I have a shed with a corrugated plastic roof. I get absurd amounts of
>water condensing under it, which drips onto the contents of the shed.
>
> Is there a way (without spending a fortune) to stop this or to collect the
> water in some way?
Increase the slope of the roof?
>water condensing under it, which drips onto the contents of the shed.
>
> Is there a way (without spending a fortune) to stop this or to collect the
> water in some way?
--
No plan survives contact with the enemy.
[Not even bunny]
Helmuth von Moltke the Elder
(\__/)
(='.'=)
(")_(")
Martin Pentreath
Feb 14, 2012, 2:11:00 PM2/14/12
to
On Feb 14, 7:03 pm, "Lieutenant Scott" <n...@spam.com> wrote:
> I have a shed with a corrugated plastic roof. I get absurd amounts of water condensing under it, which drips onto the contents of the shed.
>
> Is there a way (without spending a fortune) to stop this or to collect the water in some way?
>
Where's all the water coming from? Do you have a tumble dryer/swimming
> I have a shed with a corrugated plastic roof. I get absurd amounts of water condensing under it, which drips onto the contents of the shed.
>
> Is there a way (without spending a fortune) to stop this or to collect the water in some way?
>
pool/steam room operating down there? If so stop.
Is there electricity available? If so you could put a dehumidifier in,
if it's worth the cost to stop your stuff getting wet.
Otherwise change the shed roof to something with better thermal
properties (I don't think insulating corrugated plastic is feasible).
Lieutenant Scott
Feb 14, 2012, 2:12:16 PM2/14/12
to
On Tue, 14 Feb 2012 19:05:55 -0000, David WE Roberts <nos...@btinternet.com> wrote:
>
> "Lieutenant Scott" <n...@spam.com> wrote in message
> news:op.v9om7e2dytk5n5@i7-940...
>> I have a shed with a corrugated plastic roof. I get absurd amounts of
>> water condensing under it, which drips onto the contents of the shed.
>>
>> Is there a way (without spending a fortune) to stop this or to collect the
>> water in some way?
>
>
> Increase the slope of the roof?
Yes I suppose that is the only reasonable option (unless anyone has quicker ideas?). It's brick built, and I have a pile of matching bricks, so I could do that.
>
> "Lieutenant Scott" <n...@spam.com> wrote in message
> news:op.v9om7e2dytk5n5@i7-940...
>> I have a shed with a corrugated plastic roof. I get absurd amounts of
>> water condensing under it, which drips onto the contents of the shed.
>>
>> Is there a way (without spending a fortune) to stop this or to collect the
>> water in some way?
>
>
> Increase the slope of the roof?
What slope would you reckon is needed? It would be annoying to increase it a bit then have to do it again.
"Beam me aboard, Scotty!" [-] "Will a 2 X 4 do, Captain?"
David WE Roberts
Feb 14, 2012, 2:18:11 PM2/14/12
to
news:op.v9onmqteytk5n5@i7-940...
don't think it needs to be a massive slope.
Any chance of jacking the roof up by putting something under each joist
(piece of wood, old brick) and testing empirically?
> On Tue, 14 Feb 2012 19:05:55 -0000, David WE Roberts
> <nos...@btinternet.com> wrote:
>
>>
>> "Lieutenant Scott" <n...@spam.com> wrote in message
>> news:op.v9om7e2dytk5n5@i7-940...
>>> I have a shed with a corrugated plastic roof. I get absurd amounts of
>>> water condensing under it, which drips onto the contents of the shed.
>>>
>>> Is there a way (without spending a fortune) to stop this or to collect
>>> the
>>> water in some way?
>>
>>
>> Increase the slope of the roof?
>
> Yes I suppose that is the only reasonable option (unless anyone has
> quicker ideas?). It's brick built, and I have a pile of matching bricks,
> so I could do that.
>
> What slope would you reckon is needed? It would be annoying to increase
> it a bit then have to do it again.
Can't give you a definitive answer (looks over shoulder for expert) but I
> <nos...@btinternet.com> wrote:
>
>>
>> "Lieutenant Scott" <n...@spam.com> wrote in message
>> news:op.v9om7e2dytk5n5@i7-940...
>>> I have a shed with a corrugated plastic roof. I get absurd amounts of
>>> water condensing under it, which drips onto the contents of the shed.
>>>
>>> Is there a way (without spending a fortune) to stop this or to collect
>>> the
>>> water in some way?
>>
>>
>> Increase the slope of the roof?
>
> Yes I suppose that is the only reasonable option (unless anyone has
> quicker ideas?). It's brick built, and I have a pile of matching bricks,
> so I could do that.
>
> What slope would you reckon is needed? It would be annoying to increase
> it a bit then have to do it again.
don't think it needs to be a massive slope.
Any chance of jacking the roof up by putting something under each joist
(piece of wood, old brick) and testing empirically?
Lieutenant Scott
Feb 14, 2012, 2:27:30 PM2/14/12
to
On Tue, 14 Feb 2012 19:11:00 -0000, Martin Pentreath <martin_p...@hotmail.com> wrote:
> On Feb 14, 7:03 pm, "Lieutenant Scott" <n...@spam.com> wrote:
>> I have a shed with a corrugated plastic roof. I get absurd amounts of water condensing under it, which drips onto the contents of the shed.
>>
>> Is there a way (without spending a fortune) to stop this or to collect the water in some way?
>>
>
> Where's all the water coming from? Do you have a tumble dryer/swimming
> pool/steam room operating down there? If so stop.
Scottish weather. I very rarely see the humidity meter go below 75%!
> On Feb 14, 7:03 pm, "Lieutenant Scott" <n...@spam.com> wrote:
>> I have a shed with a corrugated plastic roof. I get absurd amounts of water condensing under it, which drips onto the contents of the shed.
>>
>> Is there a way (without spending a fortune) to stop this or to collect the water in some way?
>>
>
> Where's all the water coming from? Do you have a tumble dryer/swimming
> pool/steam room operating down there? If so stop.
> Is there electricity available? If so you could put a dehumidifier in,
> if it's worth the cost to stop your stuff getting wet.
> Otherwise change the shed roof to something with better thermal
> properties (I don't think insulating corrugated plastic is feasible).
I think I'll make sure the shed is sealed up to avoid more damp air getting in, then try tilting the roof.
If a deaf person swears, does his mother wash his hands with soap?
Lieutenant Scott
Feb 14, 2012, 2:27:42 PM2/14/12
to
On Tue, 14 Feb 2012 19:18:11 -0000, David WE Roberts <nos...@btinternet.com> wrote:
>
> "Lieutenant Scott" <n...@spam.com> wrote in message
> news:op.v9onmqteytk5n5@i7-940...
>> On Tue, 14 Feb 2012 19:05:55 -0000, David WE Roberts
>> <nos...@btinternet.com> wrote:
>>
>>>
>>> "Lieutenant Scott" <n...@spam.com> wrote in message
>>> news:op.v9om7e2dytk5n5@i7-940...
>>>> I have a shed with a corrugated plastic roof. I get absurd amounts of
>>>> water condensing under it, which drips onto the contents of the shed.
>>>>
>>>> Is there a way (without spending a fortune) to stop this or to collect
>>>> the
>>>> water in some way?
>>>
>>>
>>> Increase the slope of the roof?
>>
>> Yes I suppose that is the only reasonable option (unless anyone has
>> quicker ideas?). It's brick built, and I have a pile of matching bricks,
>> so I could do that.
>>
>> What slope would you reckon is needed? It would be annoying to increase
>> it a bit then have to do it again.
>
>
> Can't give you a definitive answer (looks over shoulder for expert) but I
> don't think it needs to be a massive slope.
> Any chance of jacking the roof up by putting something under each joist
> (piece of wood, old brick) and testing empirically?
Yes, I'll give that a go thanks.
>
> "Lieutenant Scott" <n...@spam.com> wrote in message
> news:op.v9onmqteytk5n5@i7-940...
>> On Tue, 14 Feb 2012 19:05:55 -0000, David WE Roberts
>> <nos...@btinternet.com> wrote:
>>
>>>
>>> "Lieutenant Scott" <n...@spam.com> wrote in message
>>> news:op.v9om7e2dytk5n5@i7-940...
>>>> I have a shed with a corrugated plastic roof. I get absurd amounts of
>>>> water condensing under it, which drips onto the contents of the shed.
>>>>
>>>> Is there a way (without spending a fortune) to stop this or to collect
>>>> the
>>>> water in some way?
>>>
>>>
>>> Increase the slope of the roof?
>>
>> Yes I suppose that is the only reasonable option (unless anyone has
>> quicker ideas?). It's brick built, and I have a pile of matching bricks,
>> so I could do that.
>>
>> What slope would you reckon is needed? It would be annoying to increase
>> it a bit then have to do it again.
>
>
> Can't give you a definitive answer (looks over shoulder for expert) but I
> don't think it needs to be a massive slope.
> Any chance of jacking the roof up by putting something under each joist
> (piece of wood, old brick) and testing empirically?
You know, sometimes I get the sudden urge to run around naked.
But then I just drink some Windex. It keeps me from streaking.
John Williamson
Feb 14, 2012, 2:28:30 PM2/14/12
to
Lieutenant Scott wrote:
> I have a shed with a corrugated plastic roof. I get absurd amounts of
> water condensing under it, which drips onto the contents of the shed.
>
> Is there a way (without spending a fortune) to stop this or to collect
> the water in some way?
>
Transparent or opaque sheeting fastened to the underside of the rafters?
> I have a shed with a corrugated plastic roof. I get absurd amounts of
> water condensing under it, which drips onto the contents of the shed.
>
> Is there a way (without spending a fortune) to stop this or to collect
> the water in some way?
>
The water should drop onto it, and then run down to the edges, where you
can deal with it easily by some form of gutter arrangement.
Of course, this won't deal with the cause of the condensation, just the
symptom.
--
Tciao for Now!
John.
Lieutenant Scott
Feb 14, 2012, 2:32:53 PM2/14/12
to
Is God willing to prevent evil, but not able? Then he is not omnipotent.
Is he able, but not willing? Then he is malevolent.
Is he both able and willing? Then whence cometh evil?
Is he neither able nor willing? Then why call him God?
- Epicurus (341- 270 BC)
Murmansk
Feb 14, 2012, 2:36:20 PM2/14/12
to
My garage roof is made of box profile steel and in the centre there's one sheet of see-through plastic to make a skylight. The metal sheet has a lining of OSB board but of course the window bit is not lined with OSB and that produces lots of condensation just like you describe.
I don't think changing the roof slope would be practical - you'd still get as much condensation - but it might all run down to one end.
Could you line the ceiling with some sort of boarding? That would stop it.
I don't think changing the roof slope would be practical - you'd still get as much condensation - but it might all run down to one end.
Could you line the ceiling with some sort of boarding? That would stop it.
Dave Liquorice
Feb 14, 2012, 5:15:19 PM2/14/12
to
On Tue, 14 Feb 2012 19:27:30 -0000, Lieutenant Scott wrote:
> I think I'll make sure the shed is sealed up to avoid more damp air
> getting in, ...
> I think I'll make sure the shed is sealed up to avoid more damp air
You'll never suceed well enough.
> ... then try tilting the roof.
Seems a lot of work and I wouldn't like to bet on that working all
the time either. A bit of clear buildlers polythene stapled to the
underside of the rafters will catch the drips and channel them to a
gutter/drain at the lower edge. I'd make it a little slack between
the rafters so the wet would tend to run to the center away from the
rafters. This would also encourage the wet to run down as it gathered
together.
--
Cheers
Dave.
HappyHunter
Feb 14, 2012, 5:31:07 PM2/14/12
to
On 14/02/2012 19:03, Lieutenant Scott wrote:
> I have a shed with a corrugated plastic roof. I get absurd amounts of
> water condensing under it, which drips onto the contents of the shed.
>
> Is there a way (without spending a fortune) to stop this or to collect
> the water in some way?
>
A subject close to my own heart as well ! Scotland too ..
> I have a shed with a corrugated plastic roof. I get absurd amounts of
> water condensing under it, which drips onto the contents of the shed.
>
> Is there a way (without spending a fortune) to stop this or to collect
> the water in some way?
>
I have a largely sandstone outbuilding with a clear plastic corrugated
roof, that suffers lots of condensation.
About 18 months ago, I (in my wisdom at that time), I lined the roof
with 6mm ply, the idea being I created a "cushion" so that the water
couldn't condense on the cold plastic, instead I had "warm" plywood.
It's not really helped ! The ply is rotting and going black. Well, it
was anyway .. Left a half door open for months and months and the roof
seems to be clearing a bit, but am not sure if it's the open door, or
the large bucket of road salt that has helped !!
Anyway, have now closed the door and removed the bucket of road salt,
and instead stationed 3 diy dehumidifiers around the shed, which are
basically road salt in a muslin square or tea towel hanging over a
bucket, the salt draws in the water, then drips it into the bucket.
So, over the next few months I'll see if the underside of the roof stays
drier or not. I can still see water condensing on the cold walls.
I have a theory that one wall in particular is sat in water and the
water is drawn into the shed that way. The whole outbuilding, which is
pretty big, is on an incline and I've convinced myself that the wall at
the bottom of the incline is the one causing trouble. The parts of the
building higher up the slight incline are definitely drier.
Am currently lining one wall with shelving which as part of the prep,
I've put polystyrene in and will board over with 6mm ply. Of course,
this means more water will condense onto the other bare walls !
Anyway ... line the roof, don't bother ! Of course though, there's not
as many drips of water into the shed as the poor old ply lining gets
most of it.
I think the diy dehumidifier is worth a shot. I also intend to scatter
around the shed some tins (with holes) with wood charcoal in them to act
as dehumidifiers as well.
robgraham
Feb 14, 2012, 5:39:46 PM2/14/12
to
to just live with it. In my case there really is nothing I can do as
it's clear plastic and is the only daylight source for the lean-too
section of the garage and contains my lathe, and is in near enough
daily use. Certainly the angle of my roof is pretty low to the extend
that in the recent winters I have to go and remove the snow from it.
But the condensation is not significant - if it was the lathe would
suffer and it is quite OK under an old groundsheet, so I do wonder
quite why you are getting so much moisture - I guess there may be no
damp proofing on the floor. If in fact your shed roof does not
require to give light then lining it would solve the problem.
Rob
Lieutenant Scott
Feb 14, 2012, 5:41:51 PM2/14/12
to
__________________
/\ ______________ \
/::\ \ZZZZZZZZZZZZ/\ \
/:/\.\ \ /:/\:\ \
/:/Z/\:\ \ /:/Z/\:\ \
/:/Z/__\;\_\____/:/Z/ \:\ \
/:/Z/____________\/Z/ \:\ \
\:\ \ZZZZZZZZZZZZ/\ \ \:\ \
\:\ \ \:\ \ \:\ \ \:\ \
\:\ \ \:\ \_\:\ \_____\;\ \
\:\ \ \:\___\ \ \_________\
\:\ \ /:/ZZZZ\:\ \ZZZZZZZZ/
\:\ \ /:/Z/ \:\ \ /:/Z/
\:\ \/:/Z/ \:\ \/:/Z/
\:\/:/Z/________\;\/:/Z/
\::/Z/_______itz__\/Z/
\/ZZZZZZZZZZZZZZZZZ/
Lieutenant Scott
Feb 14, 2012, 5:44:00 PM2/14/12
to
You keep believing, I'll keep evolving
Nthkentman
Feb 14, 2012, 5:46:52 PM2/14/12
to
>I have a shed with a corrugated plastic roof. I get absurd amounts of
>water condensing under it, which drips onto the contents of the shed.
>
> Is there a way (without spending a fortune) to stop this or to collect the
> water in some way?
Albeit not a steep enough roof to allow the water to run down I suggest that
>water condensing under it, which drips onto the contents of the shed.
>
> Is there a way (without spending a fortune) to stop this or to collect the
> water in some way?
if you cannot make it steeper to dry thoroughly, spray with silicone spray
to provide a less water adhesive surface and allow the water to run more
easily to the edge to a collection gutter.
Apart from that install double wall polycarbonate sheeting such as eBay item
320705397522 underneath to give better insulation and therefore less
condensation.
Lieutenant Scott
Feb 14, 2012, 6:00:17 PM2/14/12
to
On Tue, 14 Feb 2012 22:46:52 -0000, Nthkentman <nthke...@hotmail.com> wrote:
>
> "Lieutenant Scott" <n...@spam.com> wrote in message
> news:op.v9om7e2dytk5n5@i7-940...
>> I have a shed with a corrugated plastic roof. I get absurd amounts of
>> water condensing under it, which drips onto the contents of the shed.
>>
>> Is there a way (without spending a fortune) to stop this or to collect the
>> water in some way?
>
> Albeit not a steep enough roof to allow the water to run down I suggest that
> if you cannot make it steeper to dry thoroughly, spray with silicone spray
> to provide a less water adhesive surface and allow the water to run more
> easily to the edge to a collection gutter.
Silicone spray sounds like a good idea, I'll get some of that.
>
> "Lieutenant Scott" <n...@spam.com> wrote in message
> news:op.v9om7e2dytk5n5@i7-940...
>> I have a shed with a corrugated plastic roof. I get absurd amounts of
>> water condensing under it, which drips onto the contents of the shed.
>>
>> Is there a way (without spending a fortune) to stop this or to collect the
>> water in some way?
>
> Albeit not a steep enough roof to allow the water to run down I suggest that
> if you cannot make it steeper to dry thoroughly, spray with silicone spray
> to provide a less water adhesive surface and allow the water to run more
> easily to the edge to a collection gutter.
> Apart from that install double wall polycarbonate sheeting such as eBay item
> 320705397522 underneath to give better insulation and therefore less
> condensation.
Also looks expensive!
Create instant designer stubble by sucking a magnet and dipping your chin in a bowl of iron fillings.
NT
Feb 14, 2012, 8:55:01 PM2/14/12
to
On Feb 14, 11:00 pm, "Lieutenant Scott" <n...@spam.com> wrote:
goods will probably mould or rot. Just direct the condensate better.
NT
> On Tue, 14 Feb 2012 22:46:52 -0000, Nthkentman <nthkent...@hotmail.com> wrote:
>
> > "Lieutenant Scott" <n...@spam.com> wrote in message
> >news:op.v9om7e2dytk5n5@i7-940...
> >> I have a shed with a corrugated plastic roof. I get absurd amounts of
> >> water condensing under it, which drips onto the contents of the shed.
>
> >> Is there a way (without spending a fortune) to stop this or to collect the
> >> water in some way?
>
> > Albeit not a steep enough roof to allow the water to run down I suggest that
> > if you cannot make it steeper to dry thoroughly, spray with silicone spray
> > to provide a less water adhesive surface and allow the water to run more
> > easily to the edge to a collection gutter.
>
> Silicone spray sounds like a good idea, I'll get some of that.
>
> > Apart from that install double wall polycarbonate sheeting such as eBay item
> > 320705397522 underneath to give better insulation and therefore less
> > condensation.
>
> As the shed isn't heated, how does insulation help? Or is it in the evening when the outside cools and the inside does not that condensation occurs?
>
> Also looks expensive!
The condensation is on your side, if it doesnt happen your stored
>
> > "Lieutenant Scott" <n...@spam.com> wrote in message
> >news:op.v9om7e2dytk5n5@i7-940...
> >> I have a shed with a corrugated plastic roof. I get absurd amounts of
> >> water condensing under it, which drips onto the contents of the shed.
>
> >> Is there a way (without spending a fortune) to stop this or to collect the
> >> water in some way?
>
> > Albeit not a steep enough roof to allow the water to run down I suggest that
> > if you cannot make it steeper to dry thoroughly, spray with silicone spray
> > to provide a less water adhesive surface and allow the water to run more
> > easily to the edge to a collection gutter.
>
> Silicone spray sounds like a good idea, I'll get some of that.
>
> > Apart from that install double wall polycarbonate sheeting such as eBay item
> > 320705397522 underneath to give better insulation and therefore less
> > condensation.
>
> As the shed isn't heated, how does insulation help? Or is it in the evening when the outside cools and the inside does not that condensation occurs?
>
> Also looks expensive!
goods will probably mould or rot. Just direct the condensate better.
NT
Martin Brown
Feb 15, 2012, 3:16:57 AM2/15/12
to
horticultural grade bubble wrap available in large sheets. That should
provide sufficient insulation and decrease contact with cold outer skin.
Insulation and/or stopping saturated air reaching the cold surface and
possibly with active ventilation when the relative humidity is low.
Maybe an application at last for a solar powered fan ;-)
--
Regards,
Martin Brown
harry
Feb 15, 2012, 3:43:01 AM2/15/12
to
On Feb 14, 7:03 pm, "Lieutenant Scott" <n...@spam.com> wrote:
> I have a shed with a corrugated plastic roof. I get absurd amounts of water condensing under it, which drips onto the contents of the shed.
>
> Is there a way (without spending a fortune) to stop this or to collect the water in some way?
Increase the ventilation.
> I have a shed with a corrugated plastic roof. I get absurd amounts of water condensing under it, which drips onto the contents of the shed.
>
> Is there a way (without spending a fortune) to stop this or to collect the water in some way?
stuart noble
Feb 15, 2012, 3:58:08 AM2/15/12
to
pvc panels. Bone dry in there
Nightjar
Feb 15, 2012, 4:10:08 AM2/15/12
to
On 14/02/2012 19:03, Lieutenant Scott wrote:
> I have a shed with a corrugated plastic roof. I get absurd amounts of
> water condensing under it, which drips onto the contents of the shed.
>
> Is there a way (without spending a fortune) to stop this or to collect
> the water in some way?
>
You don't say whether it is clear or solid opaque plastic, so this may
> water condensing under it, which drips onto the contents of the shed.
>
> Is there a way (without spending a fortune) to stop this or to collect
> the water in some way?
>
or may not not be suitable. I had the same problem with a corrugated
steel roof on an outbuilding. I found that pushing 2" thick expanded
polystyrene sheet (something I had lying around - thinner may work as
well) up between the rafters and making sure it was well sealed around
the edges cured the problem.
Colin Bignell
Lieutenant Scott
Feb 15, 2012, 6:12:54 AM2/15/12
to
I'm currently planning (form advice in here) to spray the roof with silicone spray to make the water slide to the bottom, and if that fails, add some polythene sheeting below it to catch the drips.
Which sexual position produces the ugliest children?
Ask your mum.
Lieutenant Scott
Feb 15, 2012, 6:13:36 AM2/15/12
to
With her marriage, she got a new name and a dress.
Lieutenant Scott
Feb 15, 2012, 6:14:35 AM2/15/12
to
On Wed, 15 Feb 2012 09:10:08 -0000, Nightjar <c...@insert.my.surname.here.me.uk> wrote:
> On 14/02/2012 19:03, Lieutenant Scott wrote:
>> I have a shed with a corrugated plastic roof. I get absurd amounts of
>> water condensing under it, which drips onto the contents of the shed.
>>
>> Is there a way (without spending a fortune) to stop this or to collect
>> the water in some way?
>>
>
> You don't say whether it is clear or solid opaque plastic,
It's tinted blue, but you can see through it.
> On 14/02/2012 19:03, Lieutenant Scott wrote:
>> I have a shed with a corrugated plastic roof. I get absurd amounts of
>> water condensing under it, which drips onto the contents of the shed.
>>
>> Is there a way (without spending a fortune) to stop this or to collect
>> the water in some way?
>>
>
> You don't say whether it is clear or solid opaque plastic,
> so this may
> or may not not be suitable. I had the same problem with a corrugated
> steel roof on an outbuilding. I found that pushing 2" thick expanded
> polystyrene sheet (something I had lying around - thinner may work as
> well) up between the rafters and making sure it was well sealed around
> the edges cured the problem.
A young teenager comes home from school and asks her mother, "Is it true what Rita just told me? That babies come out of the same place where boys put their thingies?"
"Yes, dear," replies her mother, pleased that the subject had finally come up and she wouldn't have to explain it.
"But then when I have a baby, won't it knock my teeth out?"
fred
Feb 15, 2012, 6:43:17 AM2/15/12
to
On Feb 14, 10:15 pm, "Dave Liquorice"
Insulation is probably your real answer. Depending on what the rafters
and purlins are made from you could (a) staple chicken wired to the
rafters and insert insulation behind it or (b) get some of those solid
insulation panels B&Q sell and fix those between the rafters. Perhaps'
no nails ' could be used to fix the panels to the plastic sheeting.
You should really have used double insulated roofing. I used it when
building my workshop many years ago. Two layers of metal profiled
sheeting with 50mm of insulation in between Double glazed roof lights
as well. This type of roofing has been standard in commercial
buildings for many years. Don;t believe the w****r who had never tried
it and insisted condensation would still form. It doesn't.
I use a diesel powered hot air blower for heating and it must produce
a lot of water vapour but it still is no problem.
Stupid question but are you sure you don't have a few leaks ? Leaks
can be a bastard to trace as the water can run down a long way from
where the actual leak starts. Failing damage to the sheets leaks
generally occur around the fixings.
My problem is rust. I have a roller shutter door about 18' feet wide
and I have found no effective of sealing around it. A badly fitting
side door is also a problem I must get round to sometime real soon
now. Flat metal surfaces, table saw , planer, band saw, all get
covered with fitted 6mm ply covers which work a treat. Smaller tools
get sprayed with Boeshield T9, or wiped with wax, All are kept in wall
mounted cupboards or in drawers. Its a constant battle.
Paul Mc Cann
and purlins are made from you could (a) staple chicken wired to the
rafters and insert insulation behind it or (b) get some of those solid
insulation panels B&Q sell and fix those between the rafters. Perhaps'
no nails ' could be used to fix the panels to the plastic sheeting.
You should really have used double insulated roofing. I used it when
building my workshop many years ago. Two layers of metal profiled
sheeting with 50mm of insulation in between Double glazed roof lights
as well. This type of roofing has been standard in commercial
buildings for many years. Don;t believe the w****r who had never tried
it and insisted condensation would still form. It doesn't.
I use a diesel powered hot air blower for heating and it must produce
a lot of water vapour but it still is no problem.
Stupid question but are you sure you don't have a few leaks ? Leaks
can be a bastard to trace as the water can run down a long way from
where the actual leak starts. Failing damage to the sheets leaks
generally occur around the fixings.
My problem is rust. I have a roller shutter door about 18' feet wide
and I have found no effective of sealing around it. A badly fitting
side door is also a problem I must get round to sometime real soon
now. Flat metal surfaces, table saw , planer, band saw, all get
covered with fitted 6mm ply covers which work a treat. Smaller tools
get sprayed with Boeshield T9, or wiped with wax, All are kept in wall
mounted cupboards or in drawers. Its a constant battle.
Paul Mc Cann
Lieutenant Scott
Feb 15, 2012, 7:52:31 AM2/15/12
to
On Wed, 15 Feb 2012 11:43:17 -0000, fred <tpmc...@gmail.com> wrote:
> On Feb 14, 10:15 pm, "Dave Liquorice"
> <allsortsnotthis...@howhill.co.uk> wrote:
>> On Tue, 14 Feb 2012 19:27:30 -0000, Lieutenant Scott wrote:
>> > I think I'll make sure the shed is sealed up to avoid more damp air
>> > getting in, ...
>>
>> You'll never suceed well enough.
>>
>> > ... then try tilting the roof.
>>
>> Seems a lot of work and I wouldn't like to bet on that working all
>> the time either. A bit of clear buildlers polythene stapled to the
>> underside of the rafters will catch the drips and channel them to a
>> gutter/drain at the lower edge. I'd make it a little slack between
>> the rafters so the wet would tend to run to the center away from the
>> rafters. This would also encourage the wet to run down as it gathered
>> together.
>>
>> --
>> Cheers
>> Dave.
>
> Insulation is probably your real answer. Depending on what the rafters
> and purlins are made from you could (a) staple chicken wired to the
> rafters and insert insulation behind it or (b) get some of those solid
> insulation panels B&Q sell and fix those between the rafters. Perhaps'
> no nails ' could be used to fix the panels to the plastic sheeting.
I always use silicone (the stuff you seal your bath and shower with). No nails just doesn't work.
> On Feb 14, 10:15 pm, "Dave Liquorice"
> <allsortsnotthis...@howhill.co.uk> wrote:
>> On Tue, 14 Feb 2012 19:27:30 -0000, Lieutenant Scott wrote:
>> > I think I'll make sure the shed is sealed up to avoid more damp air
>> > getting in, ...
>>
>> You'll never suceed well enough.
>>
>> > ... then try tilting the roof.
>>
>> Seems a lot of work and I wouldn't like to bet on that working all
>> the time either. A bit of clear buildlers polythene stapled to the
>> underside of the rafters will catch the drips and channel them to a
>> gutter/drain at the lower edge. I'd make it a little slack between
>> the rafters so the wet would tend to run to the center away from the
>> rafters. This would also encourage the wet to run down as it gathered
>> together.
>>
>> --
>> Cheers
>> Dave.
>
> Insulation is probably your real answer. Depending on what the rafters
> and purlins are made from you could (a) staple chicken wired to the
> rafters and insert insulation behind it or (b) get some of those solid
> insulation panels B&Q sell and fix those between the rafters. Perhaps'
> no nails ' could be used to fix the panels to the plastic sheeting.
> You should really have used double insulated roofing. I used it when
> building my workshop many years ago. Two layers of metal profiled
> sheeting with 50mm of insulation in between Double glazed roof lights
> as well. This type of roofing has been standard in commercial
> buildings for many years. Don;t believe the w****r who had never tried
> it and insisted condensation would still form. It doesn't.
I thought condensation in a house was from different temperatures inside and outside, which I assumed I wouldn't have in a shed. Then again you get it in a parked car....
> I use a diesel powered hot air blower for heating and it must produce
> a lot of water vapour but it still is no problem.
>
> Stupid question but are you sure you don't have a few leaks ? Leaks
> can be a bastard to trace as the water can run down a long way from
> where the actual leak starts. Failing damage to the sheets leaks
> generally occur around the fixings.
> My problem is rust. I have a roller shutter door about 18' feet wide
> and I have found no effective of sealing around it. A badly fitting
> side door is also a problem I must get round to sometime real soon
> now. Flat metal surfaces, table saw , planer, band saw, all get
> covered with fitted 6mm ply covers which work a treat. Smaller tools
> get sprayed with Boeshield T9, or wiped with wax, All are kept in wall
> mounted cupboards or in drawers. Its a constant battle.
"Click cancel to discontinue starting" - Mac OS 9
Dave Liquorice
Feb 15, 2012, 8:59:40 AM2/15/12
to
On Wed, 15 Feb 2012 12:52:31 -0000, Lieutenant Scott wrote:
> I thought condensation in a house was from different temperatures inside
> and outside, which I assumed I wouldn't have in a shed. Then again you
> get it in a parked car....
You get condensation when ever the temperature of a surface falls
> I thought condensation in a house was from different temperatures inside
> and outside, which I assumed I wouldn't have in a shed. Then again you
> get it in a parked car....
below the dewpoint of the surrounding air. The dewpoint varies with
the relative humidity and temperature of the air.
What's happening in your shed is that it warms during the day by
solar gain, warm air can hold more water vapour than cold. Then at
night the roof panels radiate heat to the sky and cool below the
dewpoint and thus you get the condensation on them.
--
Cheers
Dave.
Nightjar
Feb 15, 2012, 9:37:58 AM2/15/12
to
On 15/02/2012 11:14, Lieutenant Scott wrote:
> On Wed, 15 Feb 2012 09:10:08 -0000, Nightjar
> <c...@insert.my.surname.here.me.uk> wrote:
>
>> On 14/02/2012 19:03, Lieutenant Scott wrote:
>>> I have a shed with a corrugated plastic roof. I get absurd amounts of
>>> water condensing under it, which drips onto the contents of the shed.
>>>
>>> Is there a way (without spending a fortune) to stop this or to collect
>>> the water in some way?
>>>
>>
>> You don't say whether it is clear or solid opaque plastic,
>
> It's tinted blue, but you can see through it.
>
>> so this may
>> or may not not be suitable. I had the same problem with a corrugated
>> steel roof on an outbuilding. I found that pushing 2" thick expanded
>> polystyrene sheet (something I had lying around - thinner may work as
>> well) up between the rafters and making sure it was well sealed around
>> the edges cured the problem.
>
> Are you sure there is no condensation above the sheet causing mould?
The problem is temperature differential, so condensation above the foam
> On Wed, 15 Feb 2012 09:10:08 -0000, Nightjar
> <c...@insert.my.surname.here.me.uk> wrote:
>
>> On 14/02/2012 19:03, Lieutenant Scott wrote:
>>> I have a shed with a corrugated plastic roof. I get absurd amounts of
>>> water condensing under it, which drips onto the contents of the shed.
>>>
>>> Is there a way (without spending a fortune) to stop this or to collect
>>> the water in some way?
>>>
>>
>> You don't say whether it is clear or solid opaque plastic,
>
> It's tinted blue, but you can see through it.
>
>> so this may
>> or may not not be suitable. I had the same problem with a corrugated
>> steel roof on an outbuilding. I found that pushing 2" thick expanded
>> polystyrene sheet (something I had lying around - thinner may work as
>> well) up between the rafters and making sure it was well sealed around
>> the edges cured the problem.
>
> Are you sure there is no condensation above the sheet causing mould?
would be improbable. At least, nothing collapsed in the c 20 years it
was in place before I sold the house.
Colin Bignell
Lieutenant Scott
Feb 15, 2012, 9:43:27 AM2/15/12
to
Religion is regarded by the common people as true, by the wise as false, and by the rulers as useful. -- Seneca the Younger 4 b.c.- 65 a.d.
Lieutenant Scott
Feb 15, 2012, 9:44:29 AM2/15/12
to
Do not adjust your mind - the fault is with reality.
Dave Liquorice
Feb 15, 2012, 10:10:58 AM2/15/12
to
On Wed, 15 Feb 2012 14:43:27 -0000, Lieutenant Scott wrote:
>> You get condensation when ever the temperature of a surface falls
>> below the dewpoint of the surrounding air.
>
>> You get condensation when ever the temperature of a surface falls
>> below the dewpoint of the surrounding air.
>
> Why is there no condensation on the inside of brick?
The brick has higher thermal mass than the thin plastic roofing
sheet. The inside surface doesn't fall below the dewpoint. It also
vertical rather tha facing the sky, ona clear night any heat radiated
to the sky just carries on going out into the universe. Heat radiated
out from a wall will probably hit something and be reflected back or
reradiated so the overall loss is a lot less.
> Or does it just soak in?
--
Cheers
Dave.
Lieutenant Scott
Feb 15, 2012, 10:50:04 AM2/15/12
to
If a deaf person swears, does his mother wash his hands with soap?
Martin Brown
Feb 15, 2012, 1:11:57 PM2/15/12
to
On 15/02/2012 15:50, Lieutenant Scott wrote:
> On Wed, 15 Feb 2012 15:10:58 -0000, Dave Liquorice
> <allsortsn...@howhill.co.uk> wrote:
>
>> On Wed, 15 Feb 2012 14:43:27 -0000, Lieutenant Scott wrote:
>>
>>>> You get condensation when ever the temperature of a surface falls
>>>> below the dewpoint of the surrounding air.
>>>
>>> Why is there no condensation on the inside of brick?
>>
>> The brick has higher thermal mass than the thin plastic roofing
>> sheet. The inside surface doesn't fall below the dewpoint. It also
>> vertical rather tha facing the sky, ona clear night any heat radiated
>> to the sky just carries on going out into the universe. Heat radiated
>> out from a wall will probably hit something and be reflected back or
>> reradiated so the overall loss is a lot less.
>>
>>> Or does it just soak in?
>>
>> Or if it does see above... B-)
>
> Surely the brick will eventually cool just as much as the roof, just
> more slowly. Both reaching the outside temperature at night.
Not really. Horizontal surfaces cool a lot faster and tend to supercool
> On Wed, 15 Feb 2012 15:10:58 -0000, Dave Liquorice
> <allsortsn...@howhill.co.uk> wrote:
>
>> On Wed, 15 Feb 2012 14:43:27 -0000, Lieutenant Scott wrote:
>>
>>>> You get condensation when ever the temperature of a surface falls
>>>> below the dewpoint of the surrounding air.
>>>
>>> Why is there no condensation on the inside of brick?
>>
>> The brick has higher thermal mass than the thin plastic roofing
>> sheet. The inside surface doesn't fall below the dewpoint. It also
>> vertical rather tha facing the sky, ona clear night any heat radiated
>> to the sky just carries on going out into the universe. Heat radiated
>> out from a wall will probably hit something and be reflected back or
>> reradiated so the overall loss is a lot less.
>>
>>> Or does it just soak in?
>>
>> Or if it does see above... B-)
>
> Surely the brick will eventually cool just as much as the roof, just
> more slowly. Both reaching the outside temperature at night.
well below ambient air temperature on still clear nights. By the time
the vertical brick walls are even close to cooling below the ambient air
temperature (if indeed they ever do) the bulk of the water vapour will
have long since have condensed out onto the much colder roof.
--
Regards,
Martin Brown
Lieutenant Scott
Feb 15, 2012, 1:47:56 PM2/15/12
to
On Wed, 15 Feb 2012 18:11:57 -0000, Martin Brown <|||newspam|||@nezumi.demon.co.uk> wrote:
> On 15/02/2012 15:50, Lieutenant Scott wrote:
>> On Wed, 15 Feb 2012 15:10:58 -0000, Dave Liquorice
>> <allsortsn...@howhill.co.uk> wrote:
>>
>>> On Wed, 15 Feb 2012 14:43:27 -0000, Lieutenant Scott wrote:
>>>
>>>>> You get condensation when ever the temperature of a surface falls
>>>>> below the dewpoint of the surrounding air.
>>>>
>>>> Why is there no condensation on the inside of brick?
>>>
>>> The brick has higher thermal mass than the thin plastic roofing
>>> sheet. The inside surface doesn't fall below the dewpoint. It also
>>> vertical rather tha facing the sky, ona clear night any heat radiated
>>> to the sky just carries on going out into the universe. Heat radiated
>>> out from a wall will probably hit something and be reflected back or
>>> reradiated so the overall loss is a lot less.
>>>
>>>> Or does it just soak in?
>>>
>>> Or if it does see above... B-)
>>
>> Surely the brick will eventually cool just as much as the roof, just
>> more slowly. Both reaching the outside temperature at night.
>
> Not really. Horizontal surfaces cool a lot faster and tend to supercool
> well below ambient air temperature on still clear nights.
How is this possible?
> On 15/02/2012 15:50, Lieutenant Scott wrote:
>> On Wed, 15 Feb 2012 15:10:58 -0000, Dave Liquorice
>> <allsortsn...@howhill.co.uk> wrote:
>>
>>> On Wed, 15 Feb 2012 14:43:27 -0000, Lieutenant Scott wrote:
>>>
>>>>> You get condensation when ever the temperature of a surface falls
>>>>> below the dewpoint of the surrounding air.
>>>>
>>>> Why is there no condensation on the inside of brick?
>>>
>>> The brick has higher thermal mass than the thin plastic roofing
>>> sheet. The inside surface doesn't fall below the dewpoint. It also
>>> vertical rather tha facing the sky, ona clear night any heat radiated
>>> to the sky just carries on going out into the universe. Heat radiated
>>> out from a wall will probably hit something and be reflected back or
>>> reradiated so the overall loss is a lot less.
>>>
>>>> Or does it just soak in?
>>>
>>> Or if it does see above... B-)
>>
>> Surely the brick will eventually cool just as much as the roof, just
>> more slowly. Both reaching the outside temperature at night.
>
> Not really. Horizontal surfaces cool a lot faster and tend to supercool
> well below ambient air temperature on still clear nights.
> By the time
> the vertical brick walls are even close to cooling below the ambient air
> temperature (if indeed they ever do) the bulk of the water vapour will
> have long since have condensed out onto the much colder roof.
"I'm prescribing these pills for you," said the doctor to the overweight patient, who tipped the scales at about three hundred pounds.
"I don't want you to swallow them. Just spill them on the floor twice a day and pick them up, one at a time."
Dave Liquorice
Feb 15, 2012, 2:12:52 PM2/15/12
to
On Wed, 15 Feb 2012 18:47:56 -0000, Lieutenant Scott wrote:
>> Not really. Horizontal surfaces cool a lot faster and tend to
supercool
>> well below ambient air temperature on still clear nights.
>
> How is this possible?
See my other post, radiation into a clear night sky just disappears
>> Not really. Horizontal surfaces cool a lot faster and tend to
supercool
>> well below ambient air temperature on still clear nights.
>
> How is this possible?
into the universe. Radiation from vertical wall will almost ceratinly
hit something and that radiation will either be reflected back or
re-radiated. Thus the heat lost form a horizontal surface is really
lost but that from a vertical one may well come back. Notice how much
warmer it is on cloudy night compared to clear one, those clouds
reflect/reradiate the heat coming up from the ground.
The super cooling happens because the universe is really rather cold
and the roof will just radiate heat out into it all night.
--
Cheers
Dave.
Lieutenant Scott
Feb 15, 2012, 2:43:39 PM2/15/12
to
Bumper sticker seen on a B-2 Stealth Bomber:
"IF YOU CAN READ THIS, THEN WE WASTED 50 BILLION BUCKS."
Dave Liquorice
Feb 15, 2012, 3:17:53 PM2/15/12
to
On Wed, 15 Feb 2012 19:43:39 -0000, Lieutenant Scott wrote:
>> The super cooling happens because the universe is really rather
cold
>> and the roof will just radiate heat out into it all night.
>
> Are you telling me that an object can actually go lower than the
> surrounding air temperature? I find that hard to believe!
Yep. Have you not seen ground frost when the air temp minima has been
>> The super cooling happens because the universe is really rather
cold
>> and the roof will just radiate heat out into it all night.
>
> Are you telling me that an object can actually go lower than the
> surrounding air temperature? I find that hard to believe!
a few degrees above freezing? Happens quite frequently. If the rate
of heat loss to the universe form a surafce is greater than the heat
gain from the atmosphere then the surface will cool below the
atmospheric temperature.
Remember that rate of heat loss is proportional to the temperature
difference the surface and air are very similar only a few degrees so
there won't be much heat transfer. By comparison the universe is a
infinite heat sink so there will be greater heat flow to the
universe.
--
Cheers
Dave.
Lieutenant Scott
Feb 15, 2012, 3:37:37 PM2/15/12
to
A blonde is walking down a creek. While she's looking around she notices Judi walking along the other side of the creek. She yells to the other blonde. "Hey, how do I get to the other side?"
Judi replies, "You are on the other side!"
Martin Brown
Feb 16, 2012, 3:51:44 AM2/16/12
to
On 15/02/2012 18:47, Lieutenant Scott wrote:
> On Wed, 15 Feb 2012 18:11:57 -0000, Martin Brown
> <|||newspam|||@nezumi.demon.co.uk> wrote:
>
>> On 15/02/2012 15:50, Lieutenant Scott wrote:
>>> On Wed, 15 Feb 2012 15:10:58 -0000, Dave Liquorice
>>> <allsortsn...@howhill.co.uk> wrote:
>>>
>>>> On Wed, 15 Feb 2012 14:43:27 -0000, Lieutenant Scott wrote:
>>>>
>>>>>> You get condensation when ever the temperature of a surface falls
>>>>>> below the dewpoint of the surrounding air.
>>>>>
>>>>> Why is there no condensation on the inside of brick?
>>>>
>>>> The brick has higher thermal mass than the thin plastic roofing
>>>> sheet. The inside surface doesn't fall below the dewpoint. It also
>>>> vertical rather tha facing the sky, ona clear night any heat radiated
>>>> to the sky just carries on going out into the universe. Heat radiated
>>>> out from a wall will probably hit something and be reflected back or
>>>> reradiated so the overall loss is a lot less.
>>>>
>>>>> Or does it just soak in?
>>>>
>>>> Or if it does see above... B-)
>>>
>>> Surely the brick will eventually cool just as much as the roof, just
>>> more slowly. Both reaching the outside temperature at night.
>>
>> Not really. Horizontal surfaces cool a lot faster and tend to supercool
>> well below ambient air temperature on still clear nights.
>
> How is this possible?
That is how the physics works. The roof is trying to reach equilibrium
> On Wed, 15 Feb 2012 18:11:57 -0000, Martin Brown
> <|||newspam|||@nezumi.demon.co.uk> wrote:
>
>> On 15/02/2012 15:50, Lieutenant Scott wrote:
>>> On Wed, 15 Feb 2012 15:10:58 -0000, Dave Liquorice
>>> <allsortsn...@howhill.co.uk> wrote:
>>>
>>>> On Wed, 15 Feb 2012 14:43:27 -0000, Lieutenant Scott wrote:
>>>>
>>>>>> You get condensation when ever the temperature of a surface falls
>>>>>> below the dewpoint of the surrounding air.
>>>>>
>>>>> Why is there no condensation on the inside of brick?
>>>>
>>>> The brick has higher thermal mass than the thin plastic roofing
>>>> sheet. The inside surface doesn't fall below the dewpoint. It also
>>>> vertical rather tha facing the sky, ona clear night any heat radiated
>>>> to the sky just carries on going out into the universe. Heat radiated
>>>> out from a wall will probably hit something and be reflected back or
>>>> reradiated so the overall loss is a lot less.
>>>>
>>>>> Or does it just soak in?
>>>>
>>>> Or if it does see above... B-)
>>>
>>> Surely the brick will eventually cool just as much as the roof, just
>>> more slowly. Both reaching the outside temperature at night.
>>
>> Not really. Horizontal surfaces cool a lot faster and tend to supercool
>> well below ambient air temperature on still clear nights.
>
> How is this possible?
in an environment where below it is a room with walls at ~4C and
surrounded by ground and air at 4C, but directly above it on a clear
night is sky with an effective radiation temperature of about -80C. It
varies a bit with the amount of haze, but on a still night the radiation
losses from an isolated horizontal surface dominate its heat loss.
Unless it is windy a plastic roof doesn't lose or gain much heat from
the air or from its supports. Still air is a rather good insulator.
Don't take my word for it. Park your car with one side to a brick wall
and all other sides exposed to the elements. The protected side may not
even get frosted. Frost invariably forms on the roof and shallow sloping
glass windows first.
>> By the time
>> the vertical brick walls are even close to cooling below the ambient air
>> temperature (if indeed they ever do) the bulk of the water vapour will
>> have long since have condensed out onto the much colder roof.
>
> But if I insulated the roof as well as the bricks, that would no longer
> apply.
surface to avoid having condensation problems.
--
Regards,
Martin Brown
Martin Brown
Feb 16, 2012, 4:05:22 AM2/16/12
to
On 15/02/2012 20:37, Lieutenant Scott wrote:
> On Wed, 15 Feb 2012 20:17:53 -0000, Dave Liquorice
> <allsortsn...@howhill.co.uk> wrote:
>
>> On Wed, 15 Feb 2012 19:43:39 -0000, Lieutenant Scott wrote:
>>
>>>> The super cooling happens because the universe is really rather
>> cold
>>>> and the roof will just radiate heat out into it all night.
>>>
>>> Are you telling me that an object can actually go lower than the
>>> surrounding air temperature? I find that hard to believe!
>>
>> Yep. Have you not seen ground frost when the air temp minima has been
>> a few degrees above freezing? Happens quite frequently. If the rate
>> of heat loss to the universe form a surafce is greater than the heat
>> gain from the atmosphere then the surface will cool below the
>> atmospheric temperature.
>>
>> Remember that rate of heat loss is proportional to the temperature
>> difference the surface and air are very similar only a few degrees so
>> there won't be much heat transfer. By comparison the universe is a
>> infinite heat sink so there will be greater heat flow to the
>> universe.
>
> Can this not be used for a refrigerator, or is the difference in
> temperature between the object and the air not enough?
On a clear night you can make ice in the desert this way under the right
> On Wed, 15 Feb 2012 20:17:53 -0000, Dave Liquorice
> <allsortsn...@howhill.co.uk> wrote:
>
>> On Wed, 15 Feb 2012 19:43:39 -0000, Lieutenant Scott wrote:
>>
>>>> The super cooling happens because the universe is really rather
>> cold
>>>> and the roof will just radiate heat out into it all night.
>>>
>>> Are you telling me that an object can actually go lower than the
>>> surrounding air temperature? I find that hard to believe!
>>
>> Yep. Have you not seen ground frost when the air temp minima has been
>> a few degrees above freezing? Happens quite frequently. If the rate
>> of heat loss to the universe form a surafce is greater than the heat
>> gain from the atmosphere then the surface will cool below the
>> atmospheric temperature.
>>
>> Remember that rate of heat loss is proportional to the temperature
>> difference the surface and air are very similar only a few degrees so
>> there won't be much heat transfer. By comparison the universe is a
>> infinite heat sink so there will be greater heat flow to the
>> universe.
>
> Can this not be used for a refrigerator, or is the difference in
> temperature between the object and the air not enough?
conditions with a very clear sky. A clear sky has an effective radiation
temperature of about -80C (~190K) whereas the ground is at ~290K and
thermal radiation scales as T^4 (3/2)^4 = 5.
So roughly 5x more thermal radiation escapes from the ground into a
clear sky than is received from it in still air this is the dominant
form of heat loss. Air doesn't deliver enough heat to make much
difference unless it is fairly windy.
You can do the experiment yourself on a clear still night that will be
frosty. Try one shallow plastic tray with exposed water and one with a
loose fitting lid on propped up a few inches from the water surface.
You might even be able to use the same largish plastic tray with only
half of it covered for an even more convincing demo.
--
Regards,
Martin Brown
Lieutenant Scott
Feb 16, 2012, 7:43:02 AM2/16/12
to
On Thu, 16 Feb 2012 08:51:44 -0000, Martin Brown <|||newspam|||@nezumi.demon.co.uk> wrote:
> On 15/02/2012 18:47, Lieutenant Scott wrote:
>> On Wed, 15 Feb 2012 18:11:57 -0000, Martin Brown
>> <|||newspam|||@nezumi.demon.co.uk> wrote:
>>
>>> On 15/02/2012 15:50, Lieutenant Scott wrote:
>>>> On Wed, 15 Feb 2012 15:10:58 -0000, Dave Liquorice
>>>> <allsortsn...@howhill.co.uk> wrote:
>>>>
>>>>> On Wed, 15 Feb 2012 14:43:27 -0000, Lieutenant Scott wrote:
>>>>>
>>>>>
>>>>> The brick has higher thermal mass than the thin plastic roofing
>>>>> sheet. The inside surface doesn't fall below the dewpoint. It also
>>>>> vertical rather tha facing the sky, ona clear night any heat radiated
>>>>> to the sky just carries on going out into the universe. Heat radiated
>>>>> out from a wall will probably hit something and be reflected back or
>>>>> reradiated so the overall loss is a lot less.
>>>>>
>>>>>
> On 15/02/2012 18:47, Lieutenant Scott wrote:
>> On Wed, 15 Feb 2012 18:11:57 -0000, Martin Brown
>> <|||newspam|||@nezumi.demon.co.uk> wrote:
>>
>>> On 15/02/2012 15:50, Lieutenant Scott wrote:
>>>> On Wed, 15 Feb 2012 15:10:58 -0000, Dave Liquorice
>>>> <allsortsn...@howhill.co.uk> wrote:
>>>>
>>>>> On Wed, 15 Feb 2012 14:43:27 -0000, Lieutenant Scott wrote:
>>>>>
>>>>>
>>>>> The brick has higher thermal mass than the thin plastic roofing
>>>>> sheet. The inside surface doesn't fall below the dewpoint. It also
>>>>> vertical rather tha facing the sky, ona clear night any heat radiated
>>>>> to the sky just carries on going out into the universe. Heat radiated
>>>>> out from a wall will probably hit something and be reflected back or
>>>>> reradiated so the overall loss is a lot less.
>>>>>
>>>>>
>>>>> Or if it does see above... B-)
>>>>
>>>> Surely the brick will eventually cool just as much as the roof, just
>>>> more slowly. Both reaching the outside temperature at night.
>>>
>>> Not really. Horizontal surfaces cool a lot faster and tend to supercool
>>> well below ambient air temperature on still clear nights.
>>
>> How is this possible?
>
> That is how the physics works. The roof is trying to reach equilibrium
> in an environment where below it is a room with walls at ~4C and
> surrounded by ground and air at 4C, but directly above it on a clear
> night is sky with an effective radiation temperature of about -80C. It
> varies a bit with the amount of haze, but on a still night the radiation
> losses from an isolated horizontal surface dominate its heat loss.
> Unless it is windy a plastic roof doesn't lose or gain much heat from
> the air or from its supports. Still air is a rather good insulator.
>
> Don't take my word for it. Park your car with one side to a brick wall
> and all other sides exposed to the elements. The protected side may not
> even get frosted. Frost invariably forms on the roof and shallow sloping
> glass windows first.
That does explain the frost on a car being completely insane sometimes. Frozen car with thermometer reading a few degrees above zero etc.
>>>>
>>>> Surely the brick will eventually cool just as much as the roof, just
>>>> more slowly. Both reaching the outside temperature at night.
>>>
>>> Not really. Horizontal surfaces cool a lot faster and tend to supercool
>>> well below ambient air temperature on still clear nights.
>>
>> How is this possible?
>
> That is how the physics works. The roof is trying to reach equilibrium
> in an environment where below it is a room with walls at ~4C and
> surrounded by ground and air at 4C, but directly above it on a clear
> night is sky with an effective radiation temperature of about -80C. It
> varies a bit with the amount of haze, but on a still night the radiation
> losses from an isolated horizontal surface dominate its heat loss.
> Unless it is windy a plastic roof doesn't lose or gain much heat from
> the air or from its supports. Still air is a rather good insulator.
>
> Don't take my word for it. Park your car with one side to a brick wall
> and all other sides exposed to the elements. The protected side may not
> even get frosted. Frost invariably forms on the roof and shallow sloping
> glass windows first.
I've seen the ground frozen and the car not. And the car frozen and the ground not. I suppose the wind is what's different between those two situations.
>>> By the time
>>> the vertical brick walls are even close to cooling below the ambient air
>>> temperature (if indeed they ever do) the bulk of the water vapour will
>>> have long since have condensed out onto the much colder roof.
>>
>> But if I insulated the roof as well as the bricks, that would no longer
>> apply.
>
> You need to prevent saturated air coming into contact with the cold
> surface to avoid having condensation problems.
Fellows, it's often easier to just give in to your wife. I mean, what's your word against thousands of hers?
Rick
Feb 16, 2012, 12:09:02 PM2/16/12
to
On 15/02/2012 11:43 AM, fred wrote:
Be surprised how easy it is to get scrap SIP panels.
Local guy got enough to build a complete barn for his cows ...
Often seen as almost zero value scrap when they pull buildings down ...
Could easily find a piece to do a shed roof.
Be surprised how easy it is to get scrap SIP panels.
Local guy got enough to build a complete barn for his cows ...
Often seen as almost zero value scrap when they pull buildings down ...
Could easily find a piece to do a shed roof.
jeffrey....@gmail.com
Jan 3, 2014, 2:36:54 PM1/3/14
to
On Tuesday, February 14, 2012 7:03:04 PM UTC, Lieutenant Scott wrote:
> I have a shed with a corrugated plastic roof. I get absurd amounts of water condensing under it, which drips onto the contents of the shed.
>
>
>
> Is there a way (without spending a fortune) to stop this or to collect the water in some way?
> TRY APPLYING A THIN FILM OF WASHING UP LIQUID TO THE ROOF.
> I have a shed with a corrugated plastic roof. I get absurd amounts of water condensing under it, which drips onto the contents of the shed.
>
>
>
> Is there a way (without spending a fortune) to stop this or to collect the water in some way?
> The three most common expressions (or famous last words) in aviation are:
>
> "Why is it doing that?", "Where the hell are we?", and "Oh Shit!"
Uncle Peter
Jan 3, 2014, 2:41:10 PM1/3/14
to
On Fri, 03 Jan 2014 19:36:54 -0000, <jeffrey....@gmail.com> wrote:
> On Tuesday, February 14, 2012 7:03:04 PM UTC, Lieutenant Scott wrote:
>
>> I have a shed with a corrugated plastic roof. I get absurd amounts of water condensing under it, which drips onto the contents of the shed.
>> Is there a way (without spending a fortune) to stop this or to collect the water in some way?
>
> TRY APPLYING A THIN FILM OF WASHING UP LIQUID TO THE ROOF.
I've sorted it by increasing the slope of the roof.
> On Tuesday, February 14, 2012 7:03:04 PM UTC, Lieutenant Scott wrote:
>
>> I have a shed with a corrugated plastic roof. I get absurd amounts of water condensing under it, which drips onto the contents of the shed.
>> Is there a way (without spending a fortune) to stop this or to collect the water in some way?
>
> TRY APPLYING A THIN FILM OF WASHING UP LIQUID TO THE ROOF.
--
We've all heard that a million monkeys banging on a million typewriters will eventually reproduce the works of Shakespeare.
Now, thanks to the Internet, we know this is not true.
Jim K
Jan 3, 2014, 3:35:13 PM1/3/14
to
Thanks colonel peter / uncle scott.. Tara
Jim K
Jim K
Brian Gaff
Jan 3, 2014, 7:46:23 PM1/3/14
to
Another old reply thread reappeared?
Brian
--
From the Sofa of Brian Gaff Reply address is active
<jeffrey....@gmail.com> wrote in message
news:810497a5-ebde-4649...@googlegroups.com...
Brian
--
From the Sofa of Brian Gaff Reply address is active
<jeffrey....@gmail.com> wrote in message
news:810497a5-ebde-4649...@googlegroups.com...
Uncle Peter
Jan 3, 2014, 7:55:55 PM1/3/14
to
On Sat, 04 Jan 2014 00:46:23 -0000, Brian Gaff <Bri...@blueyonder.co.uk> wrote:
> Another old reply thread reappeared?
>
> Brian
You replied to my very old message.
> Another old reply thread reappeared?
>
> Brian
--
Peter is listening to The Who - Behind Blue Eyes
valerie...@gmail.com
Jun 11, 2020, 6:31:59 PM6/11/20
to
One wall either side plastic roof pvc door and rest beside door pvc and plastic window in winter it's heavy dripping what can we do its built out side of backdoor part of garden
Cynic
Jun 12, 2020, 12:39:22 AM6/12/20
to
Insulate the roof. Underdraw it with a sheet of kingspan or similar. It's a technique commonly used in beehives to stop condensation dripping onto the bees, especially in winter.
Brian Gaff (Sofa)
Jun 12, 2020, 2:45:42 AM6/12/20
to
Well condensation occurs due to the air on one side being colder than the
air on the other, so that as warm air holds more moisture, when it cools by
being against a cold surface, it gives up its moisture to the plastic.
Basically if it was indoors one would try to dehumidify the air indoors or
double glaze the area or otherwise insulate. As somebody once said ye cannee
change the laws of physics!
Brian
--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
bri...@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!
<valerie...@gmail.com> wrote in message
news:c7722bdf-9b2b-42fd...@googlegroups.com...
air on the other, so that as warm air holds more moisture, when it cools by
being against a cold surface, it gives up its moisture to the plastic.
Basically if it was indoors one would try to dehumidify the air indoors or
double glaze the area or otherwise insulate. As somebody once said ye cannee
change the laws of physics!
Brian
--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
bri...@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!
<valerie...@gmail.com> wrote in message
news:c7722bdf-9b2b-42fd...@googlegroups.com...
Andrew
Jun 12, 2020, 10:30:13 AM6/12/20
to
On 11/06/2020 23:31, valerie...@gmail.com wrote:
> One wall either side plastic roof pvc door and rest beside door pvc and plastic window in winter it's heavy dripping what can we do its built out side of backdoor part of garden
>
Have you incorporated an uninsulated structure like a plastic
> One wall either side plastic roof pvc door and rest beside door pvc and plastic window in winter it's heavy dripping what can we do its built out side of backdoor part of garden
>
conservatory as part of your kitchen by removing a door,wall,
or patio door at some point. ?.
This means warm most air from inside the house is hitting the
cold uninsulated plastic roofing.
If this work was done after Building Regs 2006 (Oct) revision
then it is 'illegal', as in - you should have submitted a
building regs napplication to your council. They would have
made you upgrade the walls and ceiling of the lean-to or
whatever to the same thermal regs as the main part of the
house.
tabb...@gmail.com
Jun 12, 2020, 5:53:11 PM6/12/20
to
On Thursday, 11 June 2020 23:31:59 UTC+1, valerie...@gmail.com wrote:
> One wall either side plastic roof pvc door and rest beside door pvc and plastic window in winter it's heavy dripping what can we do its built out side of backdoor part of garden
Really depends whether your aim is to keep the damp down or just avoid getting dripped on but don't care about the damp, ie aren't keeping anything vulnerable to damp in there.
> One wall either side plastic roof pvc door and rest beside door pvc and plastic window in winter it's heavy dripping what can we do its built out side of backdoor part of garden
NT
Jim GM4DHJ ...
Jun 13, 2020, 1:20:50 AM6/13/20
to
On 11/06/2020 23:31, valerie...@gmail.com wrote:
> One wall either side plastic roof pvc door and rest beside door pvc and plastic window in winter it's heavy dripping what can we do its built out side of backdoor part of garden
>
line it with 2L2 ...
>
Andrew
Jun 13, 2020, 3:09:23 PM6/13/20
to
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