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Roofing/loft/builder recommendation...
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Gavin Walker
Dec 11, 2011, 9:21:42 AM12/11/11
to
Can anyone recommend (SNB) someone who might be able to do
some diagnosis on a perennial condensation problem in our
loft? I'm running out of ideas.
Background: it's an 80s house; fairly standard design. The
loft has always suffered heavy condensation (dripping; puddles)
in the loft since we moved in. It's fine until the weather
turns cold (like now) but then is wet all winter.
Fix #1. When we moved in the eaves were blocked with
insulation -- I thought that unblocking those would fix it.
Nope. (The wind fairly whistles through at times.)
Fix #2. The main waste pipe vents into the loft, and the
air admittance valve was broken -- I thought that replacing
that would fix it. Nope.
Fix #3. The loft hatch is very close to the bathroom. Maybe
too much damp air was seeping up there? (Getting desperate
now :-) Made the loft hatch more air tight -- didn't help.
Hence I'm looking for someone who might be able to diagnose
the root problem & suggest fixes. Is it a ventilation
problem or a problem with too much damp air? Or both? Any
advice & recommendations welcome!
Gavin
p.s.: reply to address is probably broken. Try gavin at
gavinwalker dot org if you don't want to reply here.
some diagnosis on a perennial condensation problem in our
loft? I'm running out of ideas.
Background: it's an 80s house; fairly standard design. The
loft has always suffered heavy condensation (dripping; puddles)
in the loft since we moved in. It's fine until the weather
turns cold (like now) but then is wet all winter.
Fix #1. When we moved in the eaves were blocked with
insulation -- I thought that unblocking those would fix it.
Nope. (The wind fairly whistles through at times.)
Fix #2. The main waste pipe vents into the loft, and the
air admittance valve was broken -- I thought that replacing
that would fix it. Nope.
Fix #3. The loft hatch is very close to the bathroom. Maybe
too much damp air was seeping up there? (Getting desperate
now :-) Made the loft hatch more air tight -- didn't help.
Hence I'm looking for someone who might be able to diagnose
the root problem & suggest fixes. Is it a ventilation
problem or a problem with too much damp air? Or both? Any
advice & recommendations welcome!
Gavin
p.s.: reply to address is probably broken. Try gavin at
gavinwalker dot org if you don't want to reply here.
tony sayer
Dec 11, 2011, 9:57:15 AM12/11/11
to
In article <jc2e9m$g6a$1...@newscl01ah.mathworks.com>, Gavin Walker
<gwa...@uk-gwalker0l.UK> scribeth thus
>
>Fix #2. The main waste pipe vents into the loft, and the
>air admittance valve was broken -- I thought that replacing
>that would fix it. Nope.
Well extra water vapour up there won't help matters..
>
>Fix #3. The loft hatch is very close to the bathroom. Maybe
>too much damp air was seeping up there? (Getting desperate
>now :-) Made the loft hatch more air tight -- didn't help.
Well its damp air or water laden air condensing on the cold surfaces
that are in your loft.
How much insulation do you have up there and exactly where is the water
condensing?..
>
>
>Hence I'm looking for someone who might be able to diagnose
>the root problem & suggest fixes. Is it a ventilation
>problem or a problem with too much damp air? Or both? Any
>advice & recommendations welcome!
>
>Gavin
>
>p.s.: reply to address is probably broken. Try gavin at
>gavinwalker dot org if you don't want to reply here.
>
>
X posted to UK DIY for some better advice;!...
--
Tony Sayer
<gwa...@uk-gwalker0l.UK> scribeth thus
>Can anyone recommend (SNB) someone who might be able to do
>some diagnosis on a perennial condensation problem in our
>loft? I'm running out of ideas.
>
>Background: it's an 80s house; fairly standard design. The
>loft has always suffered heavy condensation (dripping; puddles)
>in the loft since we moved in. It's fine until the weather
>turns cold (like now) but then is wet all winter.
>
>
>Fix #1. When we moved in the eaves were blocked with
>insulation -- I thought that unblocking those would fix it.
>Nope. (The wind fairly whistles through at times.)
As it should do..
>some diagnosis on a perennial condensation problem in our
>loft? I'm running out of ideas.
>
>Background: it's an 80s house; fairly standard design. The
>loft has always suffered heavy condensation (dripping; puddles)
>in the loft since we moved in. It's fine until the weather
>turns cold (like now) but then is wet all winter.
>
>
>Fix #1. When we moved in the eaves were blocked with
>insulation -- I thought that unblocking those would fix it.
>Nope. (The wind fairly whistles through at times.)
>
>Fix #2. The main waste pipe vents into the loft, and the
>air admittance valve was broken -- I thought that replacing
>that would fix it. Nope.
>
>Fix #3. The loft hatch is very close to the bathroom. Maybe
>too much damp air was seeping up there? (Getting desperate
>now :-) Made the loft hatch more air tight -- didn't help.
that are in your loft.
How much insulation do you have up there and exactly where is the water
condensing?..
>
>
>Hence I'm looking for someone who might be able to diagnose
>the root problem & suggest fixes. Is it a ventilation
>problem or a problem with too much damp air? Or both? Any
>advice & recommendations welcome!
>
>Gavin
>
>p.s.: reply to address is probably broken. Try gavin at
>gavinwalker dot org if you don't want to reply here.
>
>
--
Tony Sayer
The Natural Philosopher
Dec 11, 2011, 12:24:53 PM12/11/11
to
Air admittance valves wont stop condensation if the vent is into the
loft. They di a different job: the vent is for positive pressure release
and WILL result in condensation.
If you can take the vent up out and DOWN again through a soffit plate.
Or make a proper roof exiting pipe.
Venting the stack to the lift is a horrible bodge and may well catch you
out if the loft is well insulated.
If there is a draught whistling through that's all the ventilation you need.
The last line of attack apart from, draught proofing the hatch is a
vapour barrier UNDER the insulation - polythene or replace the rock wool
with celotex sheets and then refill with rock wool.
But my guess is on the stack vent. Until I sorted out my gable vent mine
was dripping enough condensate into the wall to blow the plaster in the
room below.
CWatters
Dec 11, 2011, 1:00:39 PM12/11/11
to
On 11/12/2011 14:21, Gavin Walker wrote:
> Can anyone recommend (SNB) someone who might be able to do
> some diagnosis on a perennial condensation problem in our
> loft? I'm running out of ideas.
>
> Background: it's an 80s house; fairly standard design. The
> loft has always suffered heavy condensation (dripping; puddles)
> in the loft since we moved in. It's fine until the weather
> turns cold (like now) but then is wet all winter.
>
>
> Fix #1. When we moved in the eaves were blocked with
> insulation -- I thought that unblocking those would fix it.
> Nope. (The wind fairly whistles through at times.)
The amount of ventilation recommended is equivalent to a 10mm slot the
> Can anyone recommend (SNB) someone who might be able to do
> some diagnosis on a perennial condensation problem in our
> loft? I'm running out of ideas.
>
> Background: it's an 80s house; fairly standard design. The
> loft has always suffered heavy condensation (dripping; puddles)
> in the loft since we moved in. It's fine until the weather
> turns cold (like now) but then is wet all winter.
>
>
> Fix #1. When we moved in the eaves were blocked with
> insulation -- I thought that unblocking those would fix it.
> Nope. (The wind fairly whistles through at times.)
full length of the eaves both sides..
http://t1.gstatic.com/images?q=tbn:ANd9GcS5VWSsQzVnGTbw5PTVbEIi9k8rA14343jqvV9v7xRxXX2khpAmJg7dx08FEg
http://www.roofconsult.co.uk/articles/tiling/tips28.htm
That works out at 10,000mm^2 per meter. Typical round soffit vents have
a free area of 2500mm^2 so you may need at least four per meter achieve
the recommended minimium area.
Apart from that look for and seal up any small holes (eg around pipes)
that allow warm humid air from the house into the loft.
Got any downlights?
Gavin Walker
Dec 11, 2011, 3:30:15 PM12/11/11
to
In article <8C1ceCBL...@bancom.co.uk>,
replacing it hasn't helped, sadly.
>How much insulation do you have up there and exactly where is the water
>condensing?..
Lots of insulation but squisked under boarding. The condensation
is on the roof itself and worse on the side that gets least
sun.
>X posted to UK DIY for some better advice;!...
Ta.
G.
tony sayer <to...@bancom.co.uk> wrote:
>In article <jc2e9m$g6a$1...@newscl01ah.mathworks.com>, Gavin Walker
><gwa...@uk-gwalker0l.UK> scribeth thus
>
>>
>In article <jc2e9m$g6a$1...@newscl01ah.mathworks.com>, Gavin Walker
><gwa...@uk-gwalker0l.UK> scribeth thus
>
>>
>>Fix #2. The main waste pipe vents into the loft, and the
>>air admittance valve was broken -- I thought that replacing
>>that would fix it. Nope.
>
>Well extra water vapour up there won't help matters..
Yes, that's why I was confident that it was the cause, but
>>air admittance valve was broken -- I thought that replacing
>>that would fix it. Nope.
>
>Well extra water vapour up there won't help matters..
replacing it hasn't helped, sadly.
>How much insulation do you have up there and exactly where is the water
>condensing?..
is on the roof itself and worse on the side that gets least
sun.
>X posted to UK DIY for some better advice;!...
G.
Gavin Walker
Dec 11, 2011, 4:33:27 PM12/11/11
to
In article <jc2p16$j43$1...@news.albasani.net>,
The Natural Philosopher <t...@invalid.invalid> wrote:
admittance valve is that it's normally closed, but will allow air
to be drawn in from the loft when a toilet is flushed (say), so
should not be allowing moisture in to the loft.
Moving it to be a normal, atmospheric vent is on the to-do list,
but I'm still not certain it's causing the condensation.
G.
The Natural Philosopher <t...@invalid.invalid> wrote:
>Gavin Walker wrote:
>First of all go to uk.d-i-y with this,.
>
>Air admittance valves wont stop condensation if the vent is into the
>loft. They di a different job: the vent is for positive pressure release
>and WILL result in condensation.
I'm suspicious of this vent, but my understanding of an air
>First of all go to uk.d-i-y with this,.
>
>Air admittance valves wont stop condensation if the vent is into the
>loft. They di a different job: the vent is for positive pressure release
>and WILL result in condensation.
admittance valve is that it's normally closed, but will allow air
to be drawn in from the loft when a toilet is flushed (say), so
should not be allowing moisture in to the loft.
Moving it to be a normal, atmospheric vent is on the to-do list,
but I'm still not certain it's causing the condensation.
G.
Brian L Johnson
Dec 11, 2011, 5:01:31 PM12/11/11
to
Gavin Walker <gwa...@uk-gwalker0l.uk> wrote:
> Can anyone recommend (SNB) someone who might be able to do
> some diagnosis on a perennial condensation problem in our
> loft? I'm running out of ideas.
>
> Background: it's an 80s house; fairly standard design. The
> loft has always suffered heavy condensation (dripping; puddles)
> in the loft since we moved in. It's fine until the weather
> turns cold (like now) but then is wet all winter.
>
>
> Fix #1. When we moved in the eaves were blocked with
> insulation -- I thought that unblocking those would fix it.
> Nope. (The wind fairly whistles through at times.)
>
> Fix #2. The main waste pipe vents into the loft, and the
> air admittance valve was broken -- I thought that replacing
> that would fix it. Nope.
>
> Fix #3. The loft hatch is very close to the bathroom. Maybe
> too much damp air was seeping up there? (Getting desperate
> now :-) Made the loft hatch more air tight -- didn't help.
Holes in the bathroom light fitting?
> Can anyone recommend (SNB) someone who might be able to do
> some diagnosis on a perennial condensation problem in our
> loft? I'm running out of ideas.
>
> Background: it's an 80s house; fairly standard design. The
> loft has always suffered heavy condensation (dripping; puddles)
> in the loft since we moved in. It's fine until the weather
> turns cold (like now) but then is wet all winter.
>
>
> Fix #1. When we moved in the eaves were blocked with
> insulation -- I thought that unblocking those would fix it.
> Nope. (The wind fairly whistles through at times.)
>
> Fix #2. The main waste pipe vents into the loft, and the
> air admittance valve was broken -- I thought that replacing
> that would fix it. Nope.
>
> Fix #3. The loft hatch is very close to the bathroom. Maybe
> too much damp air was seeping up there? (Getting desperate
> now :-) Made the loft hatch more air tight -- didn't help.
--
brianlj
Gavin Walker
Dec 11, 2011, 5:07:32 PM12/11/11
to
In article <op.v6ch4ths0v1caa@thedell>,
Brian L Johnson <no.e...@address.invalid> wrote:
get through insulation and boards. And there's a *lot* of
water up there at times -- enough for puddles!
G.
Brian L Johnson <no.e...@address.invalid> wrote:
>Gavin Walker <gwa...@uk-gwalker0l.uk> wrote:
>
>>
>> Fix #3. The loft hatch is very close to the bathroom. Maybe
>> too much damp air was seeping up there? (Getting desperate
>> now :-) Made the loft hatch more air tight -- didn't help.
>
>Holes in the bathroom light fitting?
Not that I can see but, even if there were, it'd have to
>
>>
>> Fix #3. The loft hatch is very close to the bathroom. Maybe
>> too much damp air was seeping up there? (Getting desperate
>> now :-) Made the loft hatch more air tight -- didn't help.
>
>Holes in the bathroom light fitting?
get through insulation and boards. And there's a *lot* of
water up there at times -- enough for puddles!
G.
The Natural Philosopher
Dec 12, 2011, 12:02:45 AM12/12/11
to
- do you mean ALL that is, is an air admittance valve?
Cos that is not a vent. Its an intake.
The Natural Philosopher
Dec 12, 2011, 12:03:41 AM12/12/11
to
> G.
>
>
Brian L Johnson
Dec 12, 2011, 3:26:07 AM12/12/11
to
where the bathroom light wires went up into the loft. Our loft also was
boarded and, when I lifted a few, the undersides were drenched and swollen.
But puddles on top... no, we never had that.
--
brianlj
John Aldridge
Dec 12, 2011, 3:45:46 AM12/12/11
to
In article <jc2e9m$g6a$1...@newscl01ah.mathworks.com>, gwalker@uk-
gwalker0l.UK says...
heating pump forcing hot water from the heating circuit up the expansion
pipe, where it trickled into the header tank.
Check that the water in the central heating header tank stays cold.
--
Cheers,
John
gwalker0l.UK says...
> Background: it's an 80s house; fairly standard design. The
> loft has always suffered heavy condensation (dripping; puddles)
> in the loft since we moved in. It's fine until the weather
> turns cold (like now) but then is wet all winter.
When that happened to us, the problem was a misconfigured central
> loft has always suffered heavy condensation (dripping; puddles)
> in the loft since we moved in. It's fine until the weather
> turns cold (like now) but then is wet all winter.
heating pump forcing hot water from the heating circuit up the expansion
pipe, where it trickled into the header tank.
Check that the water in the central heating header tank stays cold.
--
Cheers,
John
CWatters
Dec 12, 2011, 5:21:57 AM12/12/11
to
On 12/12/2011 08:45, John Aldridge wrote:
> In article<jc2e9m$g6a$1...@newscl01ah.mathworks.com>, gwalker@uk-
> gwalker0l.UK says...
>> Background: it's an 80s house; fairly standard design. The
>> loft has always suffered heavy condensation (dripping; puddles)
>> in the loft since we moved in. It's fine until the weather
>> turns cold (like now) but then is wet all winter.
>
> When that happened to us, the problem was a misconfigured central
> heating pump forcing hot water from the heating circuit up the expansion
> pipe, where it trickled into the header tank.
>
Technical term for that is "pumping over".
> In article<jc2e9m$g6a$1...@newscl01ah.mathworks.com>, gwalker@uk-
> gwalker0l.UK says...
>> Background: it's an 80s house; fairly standard design. The
>> loft has always suffered heavy condensation (dripping; puddles)
>> in the loft since we moved in. It's fine until the weather
>> turns cold (like now) but then is wet all winter.
>
> When that happened to us, the problem was a misconfigured central
> heating pump forcing hot water from the heating circuit up the expansion
> pipe, where it trickled into the header tank.
>
tony sayer
Dec 12, 2011, 5:51:59 AM12/12/11
to
In article <MPG.294fcf998...@news.demon.co.uk>, John Aldridge
<no....@jjdash.demon.co.uk> scribeth thus
Yes we had that when we moved here, puddles was quite appropriate;!....
--
Tony Sayer
<no....@jjdash.demon.co.uk> scribeth thus
--
Tony Sayer
Gavin Walker
Dec 12, 2011, 12:09:03 PM12/12/11
to
In article <MPG.294fcf998...@news.demon.co.uk>,
the header tank is stone cold. I'll keep trying!
G.
John Aldridge <jp...@jjdash.demon.co.uk> wrote:
>
>When that happened to us, the problem was a misconfigured central
>heating pump forcing hot water from the heating circuit up the expansion
>pipe, where it trickled into the header tank.
>
>Check that the water in the central heating header tank stays cold.
Thanks for the suggestion -- hadn't thought of that one -- but
>
>When that happened to us, the problem was a misconfigured central
>heating pump forcing hot water from the heating circuit up the expansion
>pipe, where it trickled into the header tank.
>
>Check that the water in the central heating header tank stays cold.
the header tank is stone cold. I'll keep trying!
G.
Gavin Walker
Dec 12, 2011, 12:10:53 PM12/12/11
to
In article <jc41tl$lvn$1...@news.albasani.net>,
Yup, it's an air admittance valve that had originally failed,
and so was venting into the loft. New valve fixed that problem,
so I don't think that's the source of the excess moisture.
G.
and so was venting into the loft. New valve fixed that problem,
so I don't think that's the source of the excess moisture.
G.
The Natural Philosopher
Dec 12, 2011, 2:32:30 PM12/12/11
to
under it..and over the joists. esp. over bathrooms and kitchens..
you SHOULD have enough airflow to clear moisture if its not getting in
in huge quantities.
Otherwise look for a roof leak.
> G.
>
>
>
The Natural Philosopher
Dec 12, 2011, 2:33:19 PM12/12/11
to
over sometimes pushing hot water into the loft...
danw
Dec 12, 2011, 3:01:35 PM12/12/11
to
On 11/12/2011 14:21, Gavin Walker wrote:
> Fix #3. The loft hatch is very close to the bathroom. Maybe
> too much damp air was seeping up there? (Getting desperate
> now :-) Made the loft hatch more air tight -- didn't help.
JOOI, what is the best way to make a loft match more air tight? As I
> too much damp air was seeping up there? (Getting desperate
> now :-) Made the loft hatch more air tight -- didn't help.
need to do this.
dan
Patrick Gosling
Dec 12, 2011, 3:22:30 PM12/12/11
to
In article <jc2e9m$g6a$1...@newscl01ah.mathworks.com>,
-patrick.
Gavin Walker <gwa...@uk-gwalker0l.UK> wrote:
>Background: it's an 80s house; fairly standard design. The
>loft has always suffered heavy condensation (dripping; puddles)
>in the loft since we moved in. It's fine until the weather
>turns cold (like now) but then is wet all winter.
Is it detached or semi/terraced?
>Background: it's an 80s house; fairly standard design. The
>loft has always suffered heavy condensation (dripping; puddles)
>in the loft since we moved in. It's fine until the weather
>turns cold (like now) but then is wet all winter.
-patrick.
Gavin Walker
Dec 12, 2011, 4:16:05 PM12/12/11
to
it suits our loft hatch & I had some hanging around.
G.
Andrew
Dec 12, 2011, 7:38:21 PM12/12/11
to
be water vapour from your neighbours getting past an open soffit where
your house joins the next one. One of them may have an extractor fan
going into the cavity, or even into the party wall (like my stupid
elderly neighbour has done). the same neighbour had a defective gas flue
inside her loft for years, after the plastic bolts attaching the final
bit of cement-asbestos pipe to the ridge tile had broken allowing it to
flop over and use the loft as a flue. (Took BG a while to notice this,
and also her lack of ventilation after DG had been fitted).
2. Are you on very wet ground with a high water table ?. If so, more
than normal dampness will occur below the DPC but water vapour molecules
are lighter than air, so they can rise up through the cavity and end up
in the loft (but with effective ventilation this should not be an issue).
3. Is the sarking felt broken where it laps over the fascia boards ?. If
so water could be getting into the cavity itself.
4. The north facing roof slope is usually worse - the warmth of the sun
will dry out the south slope.
5. Do you use a shower a lot ?. Do you do lots of cooking ?. Do you use
a tumbledrier without a venting kit. Is your loft hatch well sealed ?.
Have fitted downlighters to any upstairs rooms ?.
Andrew
Jeremy Nicoll - news posts
Dec 12, 2011, 10:17:08 PM12/12/11
to
tony sayer <to...@bancom.co.uk> wrote:
> In article <jc2e9m$g6a$1...@newscl01ah.mathworks.com>, Gavin Walker
> <gwa...@uk-gwalker0l.UK> scribeth thus
> >Can anyone recommend (SNB) someone who might be able to do
> >some diagnosis on a perennial condensation problem in our
> >loft? I'm running out of ideas.
> >
> >Background: it's an 80s house; fairly standard design. The
> >loft has always suffered heavy condensation (dripping; puddles)
> >in the loft since we moved in. It's fine until the weather
> >turns cold (like now) but then is wet all winter.
Condensation happens when warm wet air touches a cold surface. Why is there
> In article <jc2e9m$g6a$1...@newscl01ah.mathworks.com>, Gavin Walker
> <gwa...@uk-gwalker0l.UK> scribeth thus
> >Can anyone recommend (SNB) someone who might be able to do
> >some diagnosis on a perennial condensation problem in our
> >loft? I'm running out of ideas.
> >
> >Background: it's an 80s house; fairly standard design. The
> >loft has always suffered heavy condensation (dripping; puddles)
> >in the loft since we moved in. It's fine until the weather
> >turns cold (like now) but then is wet all winter.
warm wet air in the attic? Where's the warmth coming from? And the
wetness?
Why are you sure that it's condensation, rather than water in coming from
somewhere and, say, soaking timbers?
--
Jeremy C B Nicoll - my opinions are my own.
Email sent to my from-address will be deleted. Instead, please reply
to newsre...@wingsandbeaks.org.uk replacing "aaa" by "284".
Gavin Walker
Dec 14, 2011, 7:44:31 AM12/14/11
to
In article <XKSdnV99OOLjA3vT...@bt.com>,
think it's any more damp than any other bits of Cambridge (which is
essentially a swamp :-) but I hadn't thought of the cavity walls as a
source of damp.
My next steps are going to be to completely seal the loft hatch for
a few days to see if damp air is getting in that way; then do some
experiments with the air admittance valve; then look again for any
leaks; then give up, cry, ring a builder :-)
G.
Andrew <andrew9...@yahoo.co.uk> wrote:
>>
>1. Is your house detached ?. If it is a semi or mid-terrace then it may
>be water vapour from your neighbours getting past an open soffit where
>your house joins the next one. One of them may have an extractor fan
>going into the cavity, or even into the party wall (like my stupid
>elderly neighbour has done). the same neighbour had a defective gas flue
>inside her loft for years, after the plastic bolts attaching the final
>bit of cement-asbestos pipe to the ridge tile had broken allowing it to
>flop over and use the loft as a flue. (Took BG a while to notice this,
>and also her lack of ventilation after DG had been fitted).
>2. Are you on very wet ground with a high water table ?. If so, more
>than normal dampness will occur below the DPC but water vapour molecules
>are lighter than air, so they can rise up through the cavity and end up
>in the loft (but with effective ventilation this should not be an issue).
>3. Is the sarking felt broken where it laps over the fascia boards ?. If
>so water could be getting into the cavity itself.
>4. The north facing roof slope is usually worse - the warmth of the sun
>will dry out the south slope.
>5. Do you use a shower a lot ?. Do you do lots of cooking ?. Do you use
>a tumbledrier without a venting kit. Is your loft hatch well sealed ?.
>Have fitted downlighters to any upstairs rooms ?.
Thanks Andrew. It's detached, so can't blame the neighbours. I don't
>>
>1. Is your house detached ?. If it is a semi or mid-terrace then it may
>be water vapour from your neighbours getting past an open soffit where
>your house joins the next one. One of them may have an extractor fan
>going into the cavity, or even into the party wall (like my stupid
>elderly neighbour has done). the same neighbour had a defective gas flue
>inside her loft for years, after the plastic bolts attaching the final
>bit of cement-asbestos pipe to the ridge tile had broken allowing it to
>flop over and use the loft as a flue. (Took BG a while to notice this,
>and also her lack of ventilation after DG had been fitted).
>2. Are you on very wet ground with a high water table ?. If so, more
>than normal dampness will occur below the DPC but water vapour molecules
>are lighter than air, so they can rise up through the cavity and end up
>in the loft (but with effective ventilation this should not be an issue).
>3. Is the sarking felt broken where it laps over the fascia boards ?. If
>so water could be getting into the cavity itself.
>4. The north facing roof slope is usually worse - the warmth of the sun
>will dry out the south slope.
>5. Do you use a shower a lot ?. Do you do lots of cooking ?. Do you use
>a tumbledrier without a venting kit. Is your loft hatch well sealed ?.
>Have fitted downlighters to any upstairs rooms ?.
think it's any more damp than any other bits of Cambridge (which is
essentially a swamp :-) but I hadn't thought of the cavity walls as a
source of damp.
My next steps are going to be to completely seal the loft hatch for
a few days to see if damp air is getting in that way; then do some
experiments with the air admittance valve; then look again for any
leaks; then give up, cry, ring a builder :-)
G.
Al Grant
Dec 14, 2011, 8:15:58 AM12/14/11
to
On Dec 13, 3:17 am, Jeremy Nicoll - news posts
through the wall. If the outside grille is blocked and the duct isn't
airtight the fan will be blowing hot steamy air into the wall cavity.
Also, you could get some plastic membrane (e.g. vapour barrier)
and hang it up to divide the loft in half. Hopefully the dampness
will clearly be in one half and you can repeat as necessary to
narrow down the problem.
Or your new AAV might have failed like the old one. Try taping
a plastic bag over it and see if it fills with condensation.
<jn.nntp.scrap...@wingsandbeaks.org.uk> wrote:
> Condensation happens when warm wet air touches a cold surface. Why is there
> warm wet air in the attic? Where's the warmth coming from? And the
> wetness?
Might be worth checking the bathroom extractor, assuming it's
> Condensation happens when warm wet air touches a cold surface. Why is there
> warm wet air in the attic? Where's the warmth coming from? And the
> wetness?
through the wall. If the outside grille is blocked and the duct isn't
airtight the fan will be blowing hot steamy air into the wall cavity.
Also, you could get some plastic membrane (e.g. vapour barrier)
and hang it up to divide the loft in half. Hopefully the dampness
will clearly be in one half and you can repeat as necessary to
narrow down the problem.
Or your new AAV might have failed like the old one. Try taping
a plastic bag over it and see if it fills with condensation.
js.b1
Dec 14, 2011, 6:32:43 PM12/14/11
to
I suspect a 1980s roof did not have a lot of insulation, if any?
When a roof has little insulation it is a "warm roof".
The roof stays warm because it is heated by heat loss through the
12.5mm plasterboard of rooms below. A warm roof keeps the timbers warm
& above the dew point, and warmer air can hold more moisture than cold
air.
When a roof has a lot of insulation it is a "cold roof".
The roof is no longer heated by heat loss from below, the cold timbers
can fall below the dew point, the cold air holds less moisture. As a
result condensation can occur.
Dew point (eg, 3oC) is the air temperature at which moisture will
condense out into droplet form.
If the roof has had insulation added recently, it may be suffering
from moisture buildup. The problem is rockwool/glassfibre insulation
need only have about 2% moisture content to lose most if not all of
its insulating capability. So you need to identify 1) is moisture
getting into the roof via leaks, guttering, soil pipe, vents, etc and
2) is ventilation sufficient re soffit vents and if necessary ridge
vents and if necessary further vents part way down the roof.
Ridge vents replace ridge tiles with a grill which has a wind driven
rain trap, but allow improved air circulation. Timber is fine if it
gets wet - and then dries out. It must dry out, or at least stay below
18% moisture content. Above that and the various forms of rot will pay
you a visit, as well as make the wood interesting to various insects.
Treating wood that gets wet again is pointless, you have to remove the
source of moisture.
There are various sarking "felt" in traditional waterproof (type 1F)
and semi-permeable forms. The semi-permeable ones can cause problems
in that they do not work very well (Proctor Roofshield does, the rest
are crap in comparison). It is here were additional ventilation can be
necessary - ridge vents, mid-roof vents, improved soffit vents and
remove any moisture ingress causes.
A soil pipe should not vent into a loft, it could well have standing
water somewhere in it and at a far higher temperature than the roof
level air. The net result is a convective moisture pump continually
dumping moisture into the loft. Vent it to the outside (if necessary
via elbows or U and a soffit mounted vent.
I suspect in 10-15yrs we will find quite a few "cold now warm" roofs
that have been insulated have gone rotten from insufficient
ventilation and too high moisture ingress. Oh, one other area of
moisture ingress can be the felt where it flops into the gutter
rotting and flopping back against the wall plate and cavity (which may
or may not be closed). That is great at dumping moisture (or buckets)
down the cavity which finds its way back out. A stinky cavity is an
indication of this. Likewise birds (Swallows) can nest in the soffit
if the gap to the wall and peck the living daylights out of the felt
such that any trivial leaks are directed to areas where the water can
pool and evaporate back into the roof space. A very very stinky cavity
after birds heard twittering incessantly but not visible on the
guttering is a good indication of this. For some reason the parent
birds know how to get out, but their young do not and the net result
is feathers raining everywhere some time later and a stink. They like
to nest in soffits near soil pipes, I suspect the warmth attracts
them.
Other hole sources are around electrical fittings & pipework,
particularly anything near a bathroom. Check all extractors for sealed-
through-the-wall. The same is true for any balanced flue gas fires -
some do not realise a leak there dumps moisture into the cavity until
a rafter pushes out on a bargeboard directly above. Leaking window
frames can also dump water down the cavity, which evaporates and an
open cavity adds more water loading to the roof.
When a roof has little insulation it is a "warm roof".
The roof stays warm because it is heated by heat loss through the
12.5mm plasterboard of rooms below. A warm roof keeps the timbers warm
& above the dew point, and warmer air can hold more moisture than cold
air.
When a roof has a lot of insulation it is a "cold roof".
The roof is no longer heated by heat loss from below, the cold timbers
can fall below the dew point, the cold air holds less moisture. As a
result condensation can occur.
Dew point (eg, 3oC) is the air temperature at which moisture will
condense out into droplet form.
If the roof has had insulation added recently, it may be suffering
from moisture buildup. The problem is rockwool/glassfibre insulation
need only have about 2% moisture content to lose most if not all of
its insulating capability. So you need to identify 1) is moisture
getting into the roof via leaks, guttering, soil pipe, vents, etc and
2) is ventilation sufficient re soffit vents and if necessary ridge
vents and if necessary further vents part way down the roof.
Ridge vents replace ridge tiles with a grill which has a wind driven
rain trap, but allow improved air circulation. Timber is fine if it
gets wet - and then dries out. It must dry out, or at least stay below
18% moisture content. Above that and the various forms of rot will pay
you a visit, as well as make the wood interesting to various insects.
Treating wood that gets wet again is pointless, you have to remove the
source of moisture.
There are various sarking "felt" in traditional waterproof (type 1F)
and semi-permeable forms. The semi-permeable ones can cause problems
in that they do not work very well (Proctor Roofshield does, the rest
are crap in comparison). It is here were additional ventilation can be
necessary - ridge vents, mid-roof vents, improved soffit vents and
remove any moisture ingress causes.
A soil pipe should not vent into a loft, it could well have standing
water somewhere in it and at a far higher temperature than the roof
level air. The net result is a convective moisture pump continually
dumping moisture into the loft. Vent it to the outside (if necessary
via elbows or U and a soffit mounted vent.
I suspect in 10-15yrs we will find quite a few "cold now warm" roofs
that have been insulated have gone rotten from insufficient
ventilation and too high moisture ingress. Oh, one other area of
moisture ingress can be the felt where it flops into the gutter
rotting and flopping back against the wall plate and cavity (which may
or may not be closed). That is great at dumping moisture (or buckets)
down the cavity which finds its way back out. A stinky cavity is an
indication of this. Likewise birds (Swallows) can nest in the soffit
if the gap to the wall and peck the living daylights out of the felt
such that any trivial leaks are directed to areas where the water can
pool and evaporate back into the roof space. A very very stinky cavity
after birds heard twittering incessantly but not visible on the
guttering is a good indication of this. For some reason the parent
birds know how to get out, but their young do not and the net result
is feathers raining everywhere some time later and a stink. They like
to nest in soffits near soil pipes, I suspect the warmth attracts
them.
Other hole sources are around electrical fittings & pipework,
particularly anything near a bathroom. Check all extractors for sealed-
through-the-wall. The same is true for any balanced flue gas fires -
some do not realise a leak there dumps moisture into the cavity until
a rafter pushes out on a bargeboard directly above. Leaking window
frames can also dump water down the cavity, which evaporates and an
open cavity adds more water loading to the roof.
The Natural Philosopher
Dec 15, 2011, 5:18:51 AM12/15/11
to
js.b1 wrote:
> I suspect a 1980s roof did not have a lot of insulation, if any?
>
> When a roof has little insulation it is a "warm roof".
No. That is a roof where the insulation is just below the rafters or
> I suspect a 1980s roof did not have a lot of insulation, if any?
>
> When a roof has little insulation it is a "warm roof".
between them: A cold roof is where the insulation is at ceiling level,
tony sayer
Dec 15, 2011, 4:57:58 AM12/15/11
to
>Thanks Andrew. It's detached, so can't blame the neighbours. I don't
>think it's any more damp than any other bits of Cambridge (which is
>essentially a swamp :-) but I hadn't thought of the cavity walls as a
>source of damp.
>
>My next steps are going to be to completely seal the loft hatch for
>a few days to see if damp air is getting in that way; then do some
>experiments with the air admittance valve; then look again for any
>leaks; then give up, cry, ring a builder :-)
>
>G.
>
Have you any neighbours with a similar house and build?. Perhaps ask
>think it's any more damp than any other bits of Cambridge (which is
>essentially a swamp :-) but I hadn't thought of the cavity walls as a
>source of damp.
>
>My next steps are going to be to completely seal the loft hatch for
>a few days to see if damp air is getting in that way; then do some
>experiments with the air admittance valve; then look again for any
>leaks; then give up, cry, ring a builder :-)
>
>G.
>
them if they have the same problem which its possible they might and not
be aware of it!. We had a similar thing happen to one of our neighbours
the roof vents had all been blocked. Someone thought that they let the
cold air in!! and thus formed the condensation!.
--
Tony Sayer
Man at B&Q
Dec 15, 2011, 7:10:42 AM12/15/11
to
On Dec 14, 11:32 pm, "js.b1" <js...@ntlworld.com> wrote:
> If the roof has had insulation added recently, it may be suffering
> from moisture buildup. The problem is rockwool/glassfibre insulation
> need only have about 2% moisture content to lose most if not all of
> its insulating capability.
Which would make it a warm roof by your argument.
> If the roof has had insulation added recently, it may be suffering
> from moisture buildup. The problem is rockwool/glassfibre insulation
> need only have about 2% moisture content to lose most if not all of
> its insulating capability.
> A soil pipe should not vent into a loft,
MBQ
Man at B&Q
Dec 15, 2011, 7:09:14 AM12/15/11
to
On Dec 11, 5:24 pm, The Natural Philosopher <t...@invalid.invalid>
wrote:
> > the root problem & suggest fixes. Is it a ventilation
> > problem or a problem with too much damp air? Or both? Any
> > advice & recommendations welcome!
>
> > Gavin
>
> > p.s.: reply to address is probably broken. Try gavin at
> > gavinwalker dot org if you don't want to reply here.
not vent positive pressure. As such they are ideal for use in the
loft, obviating the need to break through the roof.
MBQ
wrote:
> Gavin Walker wrote:
> > Can anyone recommend (SNB) someone who might be able to do
> > some diagnosis on a perennial condensation problem in our
> > loft? I'm running out of ideas.
>
> > Background: it's an 80s house; fairly standard design. The
> > loft has always suffered heavy condensation (dripping; puddles)
> > in the loft since we moved in. It's fine until the weather
> > turns cold (like now) but then is wet all winter.
>
> > Can anyone recommend (SNB) someone who might be able to do
> > some diagnosis on a perennial condensation problem in our
> > loft? I'm running out of ideas.
>
> > Background: it's an 80s house; fairly standard design. The
> > loft has always suffered heavy condensation (dripping; puddles)
> > in the loft since we moved in. It's fine until the weather
> > turns cold (like now) but then is wet all winter.
>
> > Fix #1. When we moved in the eaves were blocked with
> > insulation -- I thought that unblocking those would fix it.
> > Nope. (The wind fairly whistles through at times.)
>
> > insulation -- I thought that unblocking those would fix it.
> > Nope. (The wind fairly whistles through at times.)
>
> > Fix #2. The main waste pipe vents into the loft, and the
> > air admittance valve was broken -- I thought that replacing
> > that would fix it. Nope.
>
> > air admittance valve was broken -- I thought that replacing
> > that would fix it. Nope.
>
> > Fix #3. The loft hatch is very close to the bathroom. Maybe
> > too much damp air was seeping up there? (Getting desperate
> > now :-) Made the loft hatch more air tight -- didn't help.
>
> > Hence I'm looking for someone who might be able to diagnose
> > too much damp air was seeping up there? (Getting desperate
> > now :-) Made the loft hatch more air tight -- didn't help.
>
> > the root problem & suggest fixes. Is it a ventilation
> > problem or a problem with too much damp air? Or both? Any
> > advice & recommendations welcome!
>
> > Gavin
>
> > p.s.: reply to address is probably broken. Try gavin at
> > gavinwalker dot org if you don't want to reply here.
>
> First of all go to uk.d-i-y with this,.
>
> Air admittance valves wont stop condensation if the vent is into the
> loft. They di a different job: the vent is for positive pressure release
> and WILL result in condensation.
AAVs let air *in* when the pressure in the stack is negative. They do
> First of all go to uk.d-i-y with this,.
>
> Air admittance valves wont stop condensation if the vent is into the
> loft. They di a different job: the vent is for positive pressure release
> and WILL result in condensation.
not vent positive pressure. As such they are ideal for use in the
loft, obviating the need to break through the roof.
MBQ
Man at B&Q
Dec 15, 2011, 7:12:21 AM12/15/11
to
On Dec 11, 8:30 pm, gwal...@uk-gwalker0l.UK (Gavin Walker) wrote:
> In article <8C1ceCBLTM5OF...@bancom.co.uk>,
> tony sayer <t...@bancom.co.uk> wrote:
>
> >In article <jc2e9m$g6...@newscl01ah.mathworks.com>, Gavin Walker
> ><gwal...@uk-gwalker0l.UK> scribeth thus
high up in the gable ends (if it's not a hipped roof) will give a
better air flow.
MBQ
> In article <8C1ceCBLTM5OF...@bancom.co.uk>,
> tony sayer <t...@bancom.co.uk> wrote:
>
> >In article <jc2e9m$g6...@newscl01ah.mathworks.com>, Gavin Walker
> ><gwal...@uk-gwalker0l.UK> scribeth thus
>
> >>Fix #2. The main waste pipe vents into the loft, and the
> >>air admittance valve was broken -- I thought that replacing
> >>that would fix it. Nope.
>
> >>Fix #2. The main waste pipe vents into the loft, and the
> >>air admittance valve was broken -- I thought that replacing
> >>that would fix it. Nope.
>
> >Well extra water vapour up there won't help matters..
>
> Yes, that's why I was confident that it was the cause, but
> replacing it hasn't helped, sadly.
>
> >How much insulation do you have up there and exactly where is the water
> >condensing?..
>
> Lots of insulation but squisked under boarding. The condensation
> is on the roof itself and worse on the side that gets least
> sun.
>
> >X posted to UK DIY for some better advice;!...
>
> Ta.
>
> G.
Assuming the roof is not actually leaking ridge vents or air bricks
>
> Yes, that's why I was confident that it was the cause, but
> replacing it hasn't helped, sadly.
>
> >How much insulation do you have up there and exactly where is the water
> >condensing?..
>
> Lots of insulation but squisked under boarding. The condensation
> is on the roof itself and worse on the side that gets least
> sun.
>
> >X posted to UK DIY for some better advice;!...
>
> Ta.
>
> G.
high up in the gable ends (if it's not a hipped roof) will give a
better air flow.
MBQ
js.b1
Dec 15, 2011, 9:52:44 AM12/15/11
to
Oops, thanks (both) for the correction re warm roof.
A roof space without ceiling insulation is relatively warm.
This tends to prevent roof timbers falling below the dew point of the
air in the roof space, even if there is an additional source of
moisture present.
A roof space with ceiling insulation is relatively cool.
This can result in roof timbers falling below the dew point of the air
in the roof space, but this dries out the following day or when
temporary environmental conditions improve. If there is a leak or
other source of moisture the timbers may not dry out - and above about
18% moisture content they become vulnerable to rot.
As I recall a designed Warm Roof is one with insulation on top of the
roof timber, a Cold Roof is one with insulation below the roof
timbers. Most loft conversions are Cold Roof re celotex screwed
between & below the rafters, with 50mm air gap.
A roof space without ceiling insulation is relatively warm.
This tends to prevent roof timbers falling below the dew point of the
air in the roof space, even if there is an additional source of
moisture present.
A roof space with ceiling insulation is relatively cool.
This can result in roof timbers falling below the dew point of the air
in the roof space, but this dries out the following day or when
temporary environmental conditions improve. If there is a leak or
other source of moisture the timbers may not dry out - and above about
18% moisture content they become vulnerable to rot.
As I recall a designed Warm Roof is one with insulation on top of the
roof timber, a Cold Roof is one with insulation below the roof
timbers. Most loft conversions are Cold Roof re celotex screwed
between & below the rafters, with 50mm air gap.
Gavin Walker
Dec 15, 2011, 10:57:32 AM12/15/11
to
In article <cddabdd3-6800-47b3...@w1g2000vba.googlegroups.com>,
js.b1 <js...@ntlworld.com> wrote:
Thanks for all this -- very useful. Replies here to questions
elsewhere (apologies for laziness)
>I suspect a 1980s roof did not have a lot of insulation, if any?
My guess is also "no". The house is a one-off by a local builder
so I can't compare with neighbours.
>If the roof has had insulation added recently, it may be suffering
>from moisture buildup. The problem is rockwool/glassfibre insulation
>need only have about 2% moisture content to lose most if not all of
>its insulating capability. So you need to identify 1) is moisture
>getting into the roof via leaks, guttering, soil pipe, vents, etc and
>2) is ventilation sufficient re soffit vents and if necessary ridge
>vents and if necessary further vents part way down the roof.
At the weekend I'm going to do another search for moisture leaks
from the bathroom (especially) upwards. Can't see any sign of major
external leaks.
>Ridge vents replace ridge tiles with a grill which has a wind driven
>rain trap, but allow improved air circulation.
Someone has suggested "lapVents" -- anyone tried them?
> [birds]
Ah, interesting. We do get swallows nesting somewhere up in the soffits
-- I'd love to investigate but a badly-built conservatory against the
back of the house makes access challenging...
Thanks!
G.
js.b1 <js...@ntlworld.com> wrote:
Thanks for all this -- very useful. Replies here to questions
elsewhere (apologies for laziness)
>I suspect a 1980s roof did not have a lot of insulation, if any?
so I can't compare with neighbours.
>If the roof has had insulation added recently, it may be suffering
>from moisture buildup. The problem is rockwool/glassfibre insulation
>need only have about 2% moisture content to lose most if not all of
>its insulating capability. So you need to identify 1) is moisture
>getting into the roof via leaks, guttering, soil pipe, vents, etc and
>2) is ventilation sufficient re soffit vents and if necessary ridge
>vents and if necessary further vents part way down the roof.
from the bathroom (especially) upwards. Can't see any sign of major
external leaks.
>Ridge vents replace ridge tiles with a grill which has a wind driven
>rain trap, but allow improved air circulation.
> [birds]
Ah, interesting. We do get swallows nesting somewhere up in the soffits
-- I'd love to investigate but a badly-built conservatory against the
back of the house makes access challenging...
Thanks!
G.
RobertL
Dec 15, 2011, 11:09:52 AM12/15/11
to
On Dec 15, 3:57 pm, gwal...@uk-gwalker0l.UK (Gavin Walker) wrote:
> In article <cddabdd3-6800-47b3-b845-110acc83c...@w1g2000vba.googlegroups.com>,
Have you studied the roof fro moutside using a pair of binoculars?
Sometimes you can spot places where water can get in.
Sorry to ask the obvious, but is the problem worse after rainy
weather?
Robert
> In article <cddabdd3-6800-47b3-b845-110acc83c...@w1g2000vba.googlegroups.com>,
Have you studied the roof fro moutside using a pair of binoculars?
Sometimes you can spot places where water can get in.
Sorry to ask the obvious, but is the problem worse after rainy
weather?
Robert
Gavin Walker
Dec 15, 2011, 11:16:16 AM12/15/11
to
In article <d717bfc6-ca11-41d2...@t36g2000prt.googlegroups.com>,
gutters are coping (old habit now). All appears fine, yet clearly
not so.
>Sorry to ask the obvious, but is the problem worse after rainy
>weather?
It's a good question. No, the trigger is cold weather. As soon as
the temperature drops, as it did a few weeks ago, then condensation
starts to form all over the underfelt on the roof, and stays until
we either:
1. do lots of additional ventilating & heating (fan heater up there,
loft hatch open) for a few hours a day a few days a week, or
2. Spring arrives!
More ventilation is clearly required, but I really want to find the
source of the moisture (and have a few experiments to try thanks to
the suggestions on this thread).
G.
RobertL <rober...@yahoo.com> wrote:
>On Dec 15, 3:57 pm, gwal...@uk-gwalker0l.UK (Gavin Walker) wrote:
>> In article <cddabdd3-6800-47b3-b845-110acc83c...@w1g2000vba.googlegroups.com>,
>
>Have you studied the roof fro moutside using a pair of binoculars?
>Sometimes you can spot places where water can get in.
Yup :-) I even go out when it's raining heaviliy to check that the
>On Dec 15, 3:57 pm, gwal...@uk-gwalker0l.UK (Gavin Walker) wrote:
>> In article <cddabdd3-6800-47b3-b845-110acc83c...@w1g2000vba.googlegroups.com>,
>
>Have you studied the roof fro moutside using a pair of binoculars?
>Sometimes you can spot places where water can get in.
gutters are coping (old habit now). All appears fine, yet clearly
not so.
>Sorry to ask the obvious, but is the problem worse after rainy
>weather?
the temperature drops, as it did a few weeks ago, then condensation
starts to form all over the underfelt on the roof, and stays until
we either:
1. do lots of additional ventilating & heating (fan heater up there,
loft hatch open) for a few hours a day a few days a week, or
2. Spring arrives!
More ventilation is clearly required, but I really want to find the
source of the moisture (and have a few experiments to try thanks to
the suggestions on this thread).
G.
Man at B&Q
Dec 15, 2011, 11:45:12 AM12/15/11
to
On Dec 11, 5:24 pm, The Natural Philosopher <t...@invalid.invalid>
wrote:
> Gavin Walker wrote:
> > Can anyone recommend (SNB) someone who might be able to do
> > some diagnosis on a perennial condensation problem in our
> > loft? I'm running out of ideas.
>
> > Background: it's an 80s house; fairly standard design. The
> > loft has always suffered heavy condensation (dripping; puddles)
> > in the loft since we moved in. It's fine until the weather
> > turns cold (like now) but then is wet all winter.
>
> > Fix #1. When we moved in the eaves were blocked with
> > insulation -- I thought that unblocking those would fix it.
> > Nope. (The wind fairly whistles through at times.)
>
wrote:
> Gavin Walker wrote:
> > Can anyone recommend (SNB) someone who might be able to do
> > some diagnosis on a perennial condensation problem in our
> > loft? I'm running out of ideas.
>
> > Background: it's an 80s house; fairly standard design. The
> > loft has always suffered heavy condensation (dripping; puddles)
> > in the loft since we moved in. It's fine until the weather
> > turns cold (like now) but then is wet all winter.
>
> > Fix #1. When we moved in the eaves were blocked with
> > insulation -- I thought that unblocking those would fix it.
> > Nope. (The wind fairly whistles through at times.)
>
> > Fix #2. The main waste pipe vents into the loft, and the
> > air admittance valve was broken -- I thought that replacing
> > that would fix it. Nope.
>
> > air admittance valve was broken -- I thought that replacing
> > that would fix it. Nope.
>
> > Fix #3. The loft hatch is very close to the bathroom. Maybe
> > too much damp air was seeping up there? (Getting desperate
> > now :-) Made the loft hatch more air tight -- didn't help.
>
> > Hence I'm looking for someone who might be able to diagnose
> > the root problem & suggest fixes. Is it a ventilation
> > problem or a problem with too much damp air? Or both? Any
> > advice & recommendations welcome!
>
> > Gavin
>
> > p.s.: reply to address is probably broken. Try gavin at
> > gavinwalker dot org if you don't want to reply here.
>
> First of all go to uk.d-i-y with this,.
>
> Air admittance valves wont stop condensation if the vent is into the
> loft. They di a different job: the vent is for positive pressure release
> and WILL result in condensation.
Apologies for the multiple posts in cam.misc, just spotted there was
> > too much damp air was seeping up there? (Getting desperate
> > now :-) Made the loft hatch more air tight -- didn't help.
>
> > Hence I'm looking for someone who might be able to diagnose
> > the root problem & suggest fixes. Is it a ventilation
> > problem or a problem with too much damp air? Or both? Any
> > advice & recommendations welcome!
>
> > Gavin
>
> > p.s.: reply to address is probably broken. Try gavin at
> > gavinwalker dot org if you don't want to reply here.
>
> First of all go to uk.d-i-y with this,.
>
> Air admittance valves wont stop condensation if the vent is into the
> loft. They di a different job: the vent is for positive pressure release
> and WILL result in condensation.
no follow up for uk.d-i-y
AAVs let air in, not out. They can be used in the loft.
MBQ
Man at B&Q
Dec 15, 2011, 11:42:59 AM12/15/11
to
As such, they can be used in a loft or even in habitable spaces.
MBQ
Andy Champ
Dec 15, 2011, 3:19:03 PM12/15/11
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On 15/12/2011 16:16, Gavin Walker wrote:
> It's a good question. No, the trigger is cold weather. As soon as
> the temperature drops, as it did a few weeks ago, then condensation
> starts to form all over the underfelt on the roof, and stays until
> we either:
Gavin, is your ceiling vapour proof? (usually foil fixed to the top of
> It's a good question. No, the trigger is cold weather. As soon as
> the temperature drops, as it did a few weeks ago, then condensation
> starts to form all over the underfelt on the roof, and stays until
> we either:
the ceiling plasterboard). If not the warm moist house air may be going
straight through.
Andy
Gavin Walker
Dec 16, 2011, 5:12:55 AM12/16/11
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In article <-LGdnZyAe_Kqy3fT...@eclipse.net.uk>,
I suspect it's not vapour proof... more ventilation might be the only
way forward if I can't find any other major sources of moisture.
G.
way forward if I can't find any other major sources of moisture.
G.
js.b1
Dec 16, 2011, 1:45:55 PM12/16/11
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On Dec 16, 10:12 am, gwal...@uk-gwalker0l.UK (Gavin Walker) wrote:
> I suspect it's not vapour proof... more ventilation might be the only
> way forward if I can't find any other major sources of moisture.
I am not convinced lack of foil on the back of plasterboard is a big
> I suspect it's not vapour proof... more ventilation might be the only
> way forward if I can't find any other major sources of moisture.
problem, otherwise perhaps the majority of houses would have a problem
when the loft is insulated. If that were a source of moisture you can
buy waterproof glue that you just paint on (loft side), SBR,
waterproof PVA, wall sealers etc.
Other sources - lead flashing particularly around chimney, leaking
chimney with gas fire in use (open flue gas fires kick out a lot of
moisture). Verify no extractors vent into the loft space. Check
carefully any ridge tile pointing.
Birds nesting are not so bad if they can get out, if they can not
things get smelly - they end up in odd places trying to get out and
die. They also make a mess of felt out of sight, causing any water
running down it to pool on eaves (usually visible as cracking of the
eaves plaster in the rooms below which gets worse with time).
Jeremy Nicoll - news posts
Dec 17, 2011, 3:03:32 PM12/17/11
to
gwa...@uk-gwalker0l.UK (Gavin Walker) wrote:
> No, the trigger is cold weather. As soon as the temperature drops, as it
> did a few weeks ago, then condensation starts to form all over the
> underfelt on the roof, and stays until we either:
>
> 1. do lots of additional ventilating & heating (fan heater up there,
> loft hatch open) for a few hours a day a few days a week, or
Heating the attic air will allow it to take up more moisture, but that hot
> No, the trigger is cold weather. As soon as the temperature drops, as it
> did a few weeks ago, then condensation starts to form all over the
> underfelt on the roof, and stays until we either:
>
> 1. do lots of additional ventilating & heating (fan heater up there,
> loft hatch open) for a few hours a day a few days a week, or
air will rise in the attic, not drop out of the loft hatch. I'd have
thought this would fail to clear the warm wet air from the attic. Perhaps a
ducted fan and hose dangling out of a skylight would work better?
Gavin Walker
Dec 19, 2011, 12:12:22 PM12/19/11
to
In article <mpro.lwd6ds...@wingsandbeaks.org.uk.invalid>,
absorbed, and then moist air gets blown out of the loft via
the existing cross-draft.
As soon as we get chance I'm going to add lots more ventilation
and see if that helps.
G.
Jeremy Nicoll - news posts <jn.nntp....@wingsandbeaks.org.uk> wrote:
>gwa...@uk-gwalker0l.UK (Gavin Walker) wrote:
>
>> No, the trigger is cold weather. As soon as the temperature drops, as it
>> did a few weeks ago, then condensation starts to form all over the
>> underfelt on the roof, and stays until we either:
>>
>> 1. do lots of additional ventilating & heating (fan heater up there,
>> loft hatch open) for a few hours a day a few days a week, or
>
>Heating the attic air will allow it to take up more moisture, but that hot
>air will rise in the attic, not drop out of the loft hatch. I'd have
>thought this would fail to clear the warm wet air from the attic. Perhaps a
>ducted fan and hose dangling out of a skylight would work better?
Seems to work for me. The warm air allows more moisture to be
>gwa...@uk-gwalker0l.UK (Gavin Walker) wrote:
>
>> No, the trigger is cold weather. As soon as the temperature drops, as it
>> did a few weeks ago, then condensation starts to form all over the
>> underfelt on the roof, and stays until we either:
>>
>> 1. do lots of additional ventilating & heating (fan heater up there,
>> loft hatch open) for a few hours a day a few days a week, or
>
>Heating the attic air will allow it to take up more moisture, but that hot
>air will rise in the attic, not drop out of the loft hatch. I'd have
>thought this would fail to clear the warm wet air from the attic. Perhaps a
>ducted fan and hose dangling out of a skylight would work better?
absorbed, and then moist air gets blown out of the loft via
the existing cross-draft.
As soon as we get chance I'm going to add lots more ventilation
and see if that helps.
G.
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