Venting subfloor up the chimney?

R D S

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Jul 21, 2019, 8:17:24 AM7/21/19

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I'm thinking 2 birds one stone here.....

I've been told I need better underfloor ventilation (there's no
ventilation at the back of the house, just the front).

We are doing some refurbishments so it's as good a time as any to rip
the floor up and put a couple of snorkel vents in the back wall.

And i'm blocking up a fireplace and apparently supposed to vent the
chimney. As it goes against the grain to send hard earned warm air up
the chimney I thought of venting the space under the floor into the
unused chimney instead.

It seems like a no brainer to me.

newshound

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Jul 21, 2019, 10:27:42 AM7/21/19

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And to me.

Jim GM4DHJ ...

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Jul 21, 2019, 12:39:46 PM7/21/19

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"R D S" <rsa...@yahoo.com> wrote in message
news:qh1l4h$cuj$1...@dont-email.me...

the subfloor ventilation should then go from the sublime to the
ridiculous,......

The Natural Philosopher

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Jul 21, 2019, 2:21:49 PM7/21/19

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On 21/07/2019 13:17, R D S wrote:

only possible downside is that it increases sub floor heat loss which
may be an issue if the floor is poorly insulated

--
It’s easier to fool people than to convince them that they have been fooled.
Mark Twain

tabb...@gmail.com

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Jul 21, 2019, 6:59:11 PM7/21/19

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Just do it in a way that is practical to undo. A flat we blocked the chimney in became stuffy & damp, reopening the chimney solved it.

NT

Jim GM4DHJ ...

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Jul 22, 2019, 2:11:24 AM7/22/19

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On 21/07/2019 19:21, The Natural Philosopher wrote:
> On 21/07/2019 13:17, R D S wrote:
>> I'm thinking 2 birds one stone here.....
>>
>> I've been told I need better underfloor ventilation (there's no
>> ventilation at the back of the house, just the front).
>>
>> We are doing some refurbishments so it's as good a time as any to rip
>> the floor up and put a couple of snorkel vents in the back wall.
>>
>> And i'm blocking up a fireplace and apparently supposed to vent the
>> chimney. As it goes against the grain to send hard earned warm air up
>> the chimney I thought of venting the space under the floor into the
>> unused chimney instead.
>>
>> It seems like a no brainer to me.
>
> only possible downside is that it increases sub floor heat loss which
> may be an issue if the floor is poorly insulated
>
>

yip

Jim GM4DHJ ...

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Jul 22, 2019, 2:12:29 AM7/22/19

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It's not just kooncil punters that block up ventilation then cry damp! .....

Jim GM4DHJ ...

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Jul 22, 2019, 3:59:45 AM7/22/19

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On 21/07/2019 13:17, R D S wrote:

I used to live up a hill in a very windy part of Scotland and when I
opened my front door the living room carpet rose up.....had to stick
some fibreglass wool into the terracotta underfloor vents ...

R D S

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Jul 22, 2019, 6:30:48 AM7/22/19

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On 21/07/2019 19:21, The Natural Philosopher wrote:

> On 21/07/2019 13:17, R D S wrote:
>> I'm thinking 2 birds one stone here.....
>>
>> I've been told I need better underfloor ventilation (there's no
>> ventilation at the back of the house, just the front).
>>
>> We are doing some refurbishments so it's as good a time as any to rip
>> the floor up and put a couple of snorkel vents in the back wall.
>>
>> And i'm blocking up a fireplace and apparently supposed to vent the
>> chimney. As it goes against the grain to send hard earned warm air up
>> the chimney I thought of venting the space under the floor into the
>> unused chimney instead.
>>
>> It seems like a no brainer to me.
>
> only possible downside is that it increases sub floor heat loss which
> may be an issue if the floor is poorly insulated
>
>

We're in the process of covering it with 25mm polystyrene 'boards' and
T&G Caberfloor, so should be OK.

The Natural Philosopher

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Jul 22, 2019, 7:02:38 AM7/22/19

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Make that 65mm and its still nowere near enough...

--
“when things get difficult you just have to lie”

― Jean Claud Jüncker

Andrew

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Jul 22, 2019, 11:34:06 AM7/22/19

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On 22/07/2019 11:30, R D S wrote:

30% heat loss through the floor. If any air leaks between those
inadequate insulation panels then you might as well not bother.

R D S

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Jul 22, 2019, 3:05:18 PM7/22/19

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There's nothing there now. Except the floorboards.

MSK

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Sep 2, 2020, 6:30:07 PM9/2/20

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Just read your post and I was thinking of doing the same thing. My floor is insulated but I have poor subfloor ventilation. Rather than use fans I thought I would use the redundant chimney to draw more air. How did this work out for you ?

--
For full context, visit https://www.homeownershub.com/uk-diy/venting-subfloor-up-the-chimney-1373369-.htm

Brian Gaff (Sofa)

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Sep 3, 2020, 3:56:17 AM9/3/20

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Quote the post you are replying to, especially when its old, that protal is
crap.
Brian

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R D S

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Sep 3, 2020, 12:27:39 PM9/3/20

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On 02/09/2020 23:30, MSK wrote:
> Just read your post and I was thinking of doing the same thing. My floor
> is insulated but I have poor subfloor ventilation. Rather than use fans
> I thought I would use the redundant chimney to draw more air. How did
> this work out for you ?
>

I didn't do it, largely because I forgot before I boarded over the floor
and walls!

What I did do though, and it's not mega pretty but I can live with it,
was to make a sort of internal vent (hole in the floor, adjacent hole
through external wall) in the corner* of the room and box it in.

I stuck a camera down there first and took some pictures of the timbers
which looked mint, and it will be relatively easy to remove the box and
do the same which might help when it next needs surveying**.

*It helps that this particular corner is in the centre of the room as it
is L shaped.

**Though in my experience if it's just a valuation report, surveyors
seem to do a copy and paste job of all the things that might be wrong
with a property which just serves to put off the buyer and make the bank
reluctant to lend.

George Miles

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Sep 3, 2020, 1:15:29 PM9/3/20

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https://groups.google.com/g/uk.d-i-y/c/HQ4bedZ-ugo/m/U1hEJLqcAAAJ
is the thread,
very interesting, i might vent an old wooden floor up the chimney myself...
put lots of kingspan and foam and tape the joints as someone says so dont get draughts into the room..

[g]