[Jim]

I plan to redirect our ground floor front room next year.

Currently, the walls are unplastered, and we've rewired so floorboards
are loose, so any option is possible at this point.

My question is what, if anything to do about draughts from under the
floor.

We live at a T junction, with a road running off our road straight in
front of our house. This road is a bit of a wind tunnel, and the room
we plan to decorate gets the brunt of it.

The house is Victorian, and slightly raised with large cavities under
the floor-boards. There is also a metal decorated air-grill at the
front of our house which ventilates the space under this room.

Net result is that it is seriously cold and draughty at the moment,
and I can feel quite strong cold draughts if I put my hands over the
floorboard gaps in this room.

When we've decorated the room, I plan to get an underlayed berber
style carpet, which should prevent the draughts, but I'd like it to be
as cosy as possible for my children.

Is there anything else I can do to improve insulation/carpet warmth?

I presume blocking up the air vent completely would be a bad thing? Is
it worthwhile attempting any other sort of under-floor insulation?

Thanks for your input.

[Andrew Mawson]

"Jim" wrote in message
...


I plan to redirect our ground floor front room next year.
....snip...
tion?

Thanks for your input.

To WHERE are you going to redirect it? G

AWEM

[Stuart Noble]

On 20/12/2010 12:31, Jim wrote:
I plan to redirect our ground floor front room next year.

Currently, the walls are unplastered, and we've rewired so floorboards
are loose, so any option is possible at this point.

My question is what, if anything to do about draughts from under the
floor.

We live at a T junction, with a road running off our road straight in
front of our house. This road is a bit of a wind tunnel, and the room
we plan to decorate gets the brunt of it.

The house is Victorian, and slightly raised with large cavities under
the floor-boards. There is also a metal decorated air-grill at the
front of our house which ventilates the space under this room.

Net result is that it is seriously cold and draughty at the moment,
and I can feel quite strong cold draughts if I put my hands over the
floorboard gaps in this room.

When we've decorated the room, I plan to get an underlayed berber
style carpet, which should prevent the draughts, but I'd like it to be
as cosy as possible for my children.

Is there anything else I can do to improve insulation/carpet warmth?

I presume blocking up the air vent completely would be a bad thing? Is
it worthwhile attempting any other sort of under-floor insulation?

Thanks for your input.

The idea on the ground floor is to stop draughts coming up through the
boards, but allow a free flow of air under them via the air bricks, so
your carpet should be enough. You don't lose heat downwards, so I'd say
there's no point in insulating.

[The Natural Philosopher[_2_]]

stuart noble wrote:

The idea on the ground floor is to stop draughts coming up through the
boards, but allow a free flow of air under them via the air bricks, so
your carpet should be enough. You don't lose heat downwards,

You ****ing well do.

[Mike Tomlinson]

In article
ps.com, Jim writes

I presume blocking up the air vent completely would be a bad thing?

Yes. The airflow prevents the joists from rotting. Don't do it.

Is
it worthwhile attempting any other sort of under-floor insulation?

No.

Perhaps put down a layer of thick polythene tucked under the skirting
boards if there is enough of a gap, then the underlay, then the carpet?

FWIW, I live in s similar house to that you have described. The floors
are stripped and varnished, and I love the look, but it's too draughty
and difficult to heat, especially in this weather, so I'll also be
putting carpet down when I get round to decorating.

--
(\__/)
(='.'=)
(")_(")

[Tabby]

On Dec 20, 2:23*pm, The Natural Philosopher
wrote:
stuart noble wrote:
The idea on the ground floor is to stop draughts coming up through the
boards, but allow a free flow of air under them via the air bricks, so
your carpet should be enough. You don't lose heat downwards,

You ****ing well do.

Yeah, that was a bit daft.

Don't block the vents, unless you want the whole floor structure to
slowly rot away. The ideal thing t do is lift floorboards, fit
insulation between joists, add a VB over the top and re-lay the
boards. The not so ideal thing is to jsut rely on underlay to stop
drafts and not have insulation - but it sounds like now is as good a
time as any to insulate it.


NT

[Stuart Noble]

On 20/12/2010 14:23, The Natural Philosopher wrote:
stuart noble wrote:

The idea on the ground floor is to stop draughts coming up through the
boards, but allow a free flow of air under them via the air bricks, so
your carpet should be enough. You don't lose heat downwards,

You ****ing well do.

With a decent carpet/underlay you're going to lose what? 5% of the total
heat loss? In most cases that would be a small saving for a lot of work

[The Natural Philosopher[_2_]]

Mike Tomlinson wrote:
In article
ps.com, Jim writes

I presume blocking up the air vent completely would be a bad thing?

Yes. The airflow prevents the joists from rotting. Don't do it.

Is
it worthwhile attempting any other sort of under-floor insulation?

No.

yes.

lift boardsd, fit celotex/kingspan between, foil tape over the whole
lot, refit boards.


result no draughts and about 5 times better insulation than carpet.

[Ronald Raygun]

Tabby wrote:

Don't block the vents, unless you want the whole floor structure to
slowly rot away. The ideal thing t do is lift floorboards, fit
insulation between joists, add a VB over the top and re-lay the
boards.

I don't think that's a good idea. The whole point of under floor
ventilation is to eliminate stagnant air which promotes rot, which
affects not only the joists but the floorboards as well. If you're
going to wrap (even just the under-side of) the floorboards in a vapour
proof skin, you are *creating* pockets of stagnant air, defeating the
purpose of the ventilation, thereby putting the floor boards at risk.

You need to remember that a certain amount of draught is actually a
good thing, otherwise the room becomes too stuffy.

The not so ideal thing is to jsut rely on underlay to stop
drafts and not have insulation - but it sounds like now is as good a
time as any to insulate it.

I think it's best not to insulate with anything non-permeable. Use
underlay if you must, but with beautifully varnished floorboards, the
in-character thing is to have rugs, not wall-to-wall carpet. With rugs
you don't want an underlay that's too thick, or you'll keep tripping over
the rug edges. Worth a try is thin cardboard.

If you can identify any spots where the draught is excessive, caulking
the gaps with ordinary string may be effective.

[harry]

On Dec 20, 12:31*pm, Jim wrote:
I plan to redirect our ground floor front room next year.

Currently, the walls are unplastered, and we've rewired so floorboards
are loose, so any option is possible at this point.

My question is what, if anything to do about draughts from under the
floor.

We live at a T junction, with a road running off our road straight in
front of our house. This road is a bit of a wind tunnel, and the room
we plan to decorate gets the brunt of it.

The house is Victorian, and slightly raised with large cavities under
the floor-boards. There is also a metal decorated air-grill at the
front of our house which ventilates the space under this room.

Net result is that it is seriously cold and draughty at the moment,
and I can feel quite strong cold draughts if I put my hands over the
floorboard gaps in this room.

When we've decorated the room, I plan to get an underlayed berber
style carpet, which should prevent the draughts, but I'd like it to be
as cosy as possible for my children.

Is there anything else I can do to improve insulation/carpet warmth?

I presume blocking up the air vent completely would be a bad thing? Is
it worthwhile attempting any other sort of under-floor insulation?

Thanks for your input.

If you can get under your floor I would insulate between the joists
with rigid foam boards, stuck in with foam. (Cut them undersize,
support with temporary nails & fill the gap with the foam) You must
fill every little gap.
If you have to lift the boards, they never go back the same, may will
get broken and the edges damaged so you may as well replace them. New
T&G i floorboards are available but expensive. There is special T&G
chipboard for flooring, thats what I have used. When complete go round
the floorboard/skirting gap and fill up with canned foam.
Don't block the air vents it encourages rot.

[Jim]

On Dec 20, 2:07*pm, "Andrew Mawson"
wrote:
"Jim" wrote in message

....

I plan to redirect our ground floor front room next year.

...snip...
tion?



Thanks for your input.

To WHERE are you going to redirect it? G

AWEM

...oops times like this when you think maybe you're too geeky...

[Jim]

On Dec 20, 4:49*pm, The Natural Philosopher
wrote:
Mike Tomlinson wrote:
In article
ps.com, Jim writes

I presume blocking up the air vent completely would be a bad thing?

Yes. *The airflow prevents the joists from rotting. Don't do it.

Is
it worthwhile attempting any other sort of under-floor insulation?

No.

yes.

* lift boardsd, fit celotex/kingspan between, foil tape over the whole
lot, refit boards.

result no draughts and about 5 times better insulation than carpet.

How thick is a layer of celotex/kingspan? Also, what do you mean by
foil tape?

Also, only some of the boards are already up, so I'd rather not lift
them all unless I had to. Would a combination of your's and Mike's
suggestions work?

That is to say, fix all the floorboards, then lay celotex/kingspan
(I'll have to look those up), then foil tape on top of that, and then
let the fitters lay underlay and carpet ontop of that? That would be a
lot less effort intensive.

[Tabby]

On Dec 20, 5:37*pm, Ronald Raygun
wrote:
Tabby wrote:

Don't block the vents, unless you want the whole floor structure to
slowly rot away. The ideal thing t do is lift floorboards, fit
insulation between joists, add a VB over the top and re-lay the
boards.

I don't think that's a good idea. *The whole point of under floor
ventilation is to eliminate stagnant air which promotes rot, which
affects not only the joists but the floorboards as well. *If you're
going to wrap (even just the under-side of) the floorboards in a vapour
proof skin, you are *creating* pockets of stagnant air, defeating the
purpose of the ventilation, thereby putting the floor boards at risk.

You need to remember that a certain amount of draught is actually a
good thing, otherwise the room becomes too stuffy.

The not so ideal thing is to jsut rely on underlay to stop
drafts and not have insulation - but it sounds like now is as good a
time as any to insulate it.

I think it's best not to insulate with anything non-permeable. *Use
underlay if you must, but with beautifully varnished floorboards, the
in-character thing is to have rugs, not wall-to-wall carpet. *With rugs
you don't want an underlay that's too thick, or you'll keep tripping over
the rug edges. *Worth a try is thin cardboard.

If you can identify any spots where the draught is excessive, caulking
the gaps with ordinary string may be effective.


The point of underfloor ventilation is to conduct away the damp that
evaporates from the earth below, so RH doesnt rise high enough to
cause rot. If you insulate between the josits with no VB, you'd be
right, condensation and rot could occur. But with insulation and VB
above all is well.


NT

[Mike Tomlinson]

In article
s.com, Jim writes

That is to say, fix all the floorboards, then lay celotex/kingspan
(I'll have to look those up), then foil tape on top of that, and then
let the fitters lay underlay and carpet ontop of that?

Celotex is a foil-backed insulation mat, about an inch thick. It
wouldn't stand up to being walked on, even with underlay and carpet on
top. It's used for things like insulation between the roof joists
during a loft conversion, for example.

I don't agree with TNP here. There would be some heat loss through the
floor, but not much, certainly not worth the effort of following his
suggestion of lifting the boards and fitting celotex between the joists,
then re-laying. As others have said, you'd also be creating pockets of
stagnant air between the celotex and the floorboards.

My opinion.

--
(\__/)
(='.'=)
(")_(")

[Tim Watts]

On 21/12/10 06:07, Mike Tomlinson wrote:
In
s.com, writes

That is to say, fix all the floorboards, then lay celotex/kingspan
(I'll have to look those up), then foil tape on top of that, and then
let the fitters lay underlay and carpet ontop of that?

Celotex is a foil-backed insulation mat, about an inch thick. It
wouldn't stand up to being walked on, even with underlay and carpet on
top. It's used for things like insulation between the roof joists
during a loft conversion, for example.

I don't agree with TNP here. There would be some heat loss through the
floor, but not much, certainly not worth the effort of following his
suggestion of lifting the boards and fitting celotex between the joists,
then re-laying. As others have said, you'd also be creating pockets of
stagnant air between the celotex and the floorboards.

My opinion.


Can the small amount of vapour in the floorboards breath up through the
underlay and carpet?

Unless there is a vapour barrier, I would have thought so.

I see no problems with this approach as long as there is a breathing
path from everything above the celotext into the room, and what's under
the celotex being open to the underfloor vents.

--
Tim Watts

[geraldthehamster[_2_]]

On 20 Dec, 12:31, Jim wrote:
I plan to redirect our ground floor front room next year.

Currently, the walls are unplastered, and we've rewired so floorboards
are loose, so any option is possible at this point.

My question is what, if anything to do about draughts from under the
floor.

We live at a T junction, with a road running off our road straight in
front of our house. This road is a bit of a wind tunnel, and the room
we plan to decorate gets the brunt of it.

The house is Victorian, and slightly raised with large cavities under
the floor-boards. There is also a metal decorated air-grill at the
front of our house which ventilates the space under this room.

Net result is that it is seriously cold and draughty at the moment,
and I can feel quite strong cold draughts if I put my hands over the
floorboard gaps in this room.

When we've decorated the room, I plan to get an underlayed berber
style carpet, which should prevent the draughts, but I'd like it to be
as cosy as possible for my children.

Is there anything else I can do to improve insulation/carpet warmth?

I presume blocking up the air vent completely would be a bad thing? Is
it worthwhile attempting any other sort of under-floor insulation?

Thanks for your input.

I'm in a similar position and this is what I plan to do.

I sanded and varnished several of my downstairs floors last year, and
am now kicking myself for not taking the opportunity to take all or
most of the boards up and insulate underneath first. Not only are the
boards cold under foot (even through rugs), but despite the greatest
care I have gaps and draughts where boards have had to come up for
plumbing and electrics (someone said in a similar thread in an other
place that they'd totted up all the gaps and holes in their floor, and
if they were all in once place they'd amount to an eight inch square
hole).

I have one more room to do, and I'm going to start by lifting all the
boards. It's a job, but a job you only have to do once. I might cut
the tongues out first, to get them up easier, as once I've insulated,
tongues won't matter.

What you need to do is insulate between the joists, putting the
floorboards into the warm zone of the room.

The easiest way to insulate is probably to use space blanket, which is
a roll insulation encapsulated in plastic to avoid mess. It is rolled
out between the joists and supported on netting or similar. My problem
with this is that the standard size is 370mm wide, and assumes that
your joists are at 400 centres, whereas mine, annoyingly, are at 430
centres, so I'd have a gap. This leaves me the option of using
messier, unencapsulated roll insulation, or what I'll probably do
which is buy seconds of 50mm Kingspan, cut to size and fix in place
with PU foam.

Where my previously-sanded floors are concerned, I had a plan to lift
a couple of floorboards in four or five places across the floor, and
pull space blanket through, under the floor, between the joists,
supporting it where I could. Unfortunately I have this width issue so
I'm not sure what approach I'll take to that now - possibly pull up a
lot more boards than I had intended, and use Kingspan again.

Important issues are electric cabling and central heating pipes -
cable should not be buried in insulation as it can theoretically
overheat and become a fire hazard, so it needs to run above it. I also
need access to my central heating pipework (in case I want to
reconfigure the radiators or access the Speedfit connectors, so I need
to make sure that's abpve the insulation too - which has an obvious
other benefit).

As people have said, on no account block up your air bricks, as air
circulation to the bottom of the joists is essential for the avoidance
of rot. I think worrying about the floorboards is unnecessary, as Tim
Watts says.

I've had three winters here now and dealt with a lot of the other
insulation issues that the house has - I'm convinced now that a major
part of the cold feel that is left is down to the floors. Especially
when outside is minus fifteen. I've yet to hear anyone say they
insulated their floor, but considered it a waste of time. You can't
build anything new without insulating the floor...

Cheers
Richard

[geraldthehamster[_2_]]

On 21 Dec, 06:07, Mike Tomlinson wrote:

Celotex is a foil-backed insulation mat, about an inch thick. *

That's a bit misleading. There is more than one Celotex product, but
the most common is a rigid foam board, usually foil backed, that comes
in sizes from one inch up to - actually I don't know, but certainly
more than seven inches. It's not a mat that you can lay on top of
floorboards and fix carpet to.

Cheers
Richard

[The Natural Philosopher[_2_]]

stuart noble wrote:
On 20/12/2010 14:23, The Natural Philosopher wrote:
stuart noble wrote:

The idea on the ground floor is to stop draughts coming up through the
boards, but allow a free flow of air under them via the air bricks, so
your carpet should be enough. You don't lose heat downwards,

You ****ing well do.

With a decent carpet/underlay you're going to lose what? 5% of the total
heat loss? In most cases that would be a small saving for a lot of work

make that 85% if the room is wall insulated with DG.

[The Natural Philosopher[_2_]]

Jim wrote:
On Dec 20, 4:49 pm, The Natural Philosopher
wrote:
Mike Tomlinson wrote:
In article
ps.com, Jim writes
I presume blocking up the air vent completely would be a bad thing?
Yes. The airflow prevents the joists from rotting. Don't do it.
Is
it worthwhile attempting any other sort of under-floor insulation?
No.
yes.

lift boardsd, fit celotex/kingspan between, foil tape over the whole
lot, refit boards.

result no draughts and about 5 times better insulation than carpet.

How thick is a layer of celotex/kingspan? Also, what do you mean by
foil tape?

variable. Suggest 50mm minimum.

Celotex is foill faced, you buy Al. tape to go over the board face and
the joists its wedged between. Makes a contonuous draught and vapour
barrier.

[The Natural Philosopher[_2_]]

Mike Tomlinson wrote:
In article
s.com, Jim writes

That is to say, fix all the floorboards, then lay celotex/kingspan
(I'll have to look those up), then foil tape on top of that, and then
let the fitters lay underlay and carpet ontop of that?

Celotex is a foil-backed insulation mat, about an inch thick. It
wouldn't stand up to being walked on, even with underlay and carpet on
top. It's used for things like insulation between the roof joists
during a loft conversion, for example.

I don't agree with TNP here. There would be some heat loss through the
floor, but not much, certainly not worth the effort of following his
suggestion of lifting the boards and fitting celotex between the joists,
then re-laying.

Do the calculations before you make such opinions.

Would you want a wall the size of your floor, cosnsisting of leaky
floorboards just covered with a carpet and underlay with a -5C 15mph
wind the other side?

yet a well vented underfloor space is just that.

Compared with a solid floor, where the ground itself acts as an
insulator, suspended wood is a complete heat loss disaster area
especially when its well ventilated.
..



As others have said, you'd also be creating pockets of
stagnant air between the celotex and the floorboards.


The celotex is flush with the top of the boards.

BUT creating pockets if stagnant air is precisely what an insulation
material does anyway, so its a silly thing for you to say, twice over.

My opinion.

[The Natural Philosopher[_2_]]

Ronald Raygun wrote:
Tabby wrote:

Don't block the vents, unless you want the whole floor structure to
slowly rot away. The ideal thing t do is lift floorboards, fit
insulation between joists, add a VB over the top and re-lay the
boards.

I don't think that's a good idea. The whole point of under floor
ventilation is to eliminate stagnant air which promotes rot, which
affects not only the joists but the floorboards as well.

No its not.

Its to prevent condensation on cold beams.

If they are vapour barriered, modest ventilation the works.



If you're
going to wrap (even just the under-side of) the floorboards in a vapour
proof skin, you are *creating* pockets of stagnant air, defeating the
purpose of the ventilation, thereby putting the floor boards at risk.


Utter tosh. You neither understand how the insulation is applied, nor why.


Celotex is made and approved for exactly this scenario: roof joists with
eaves venting behind, and habitable space inside.


You need to remember that a certain amount of draught is actually a
good thing, otherwise the room becomes too stuffy.


Absolete tosh.

That room air change ion a modern insulated house is controlled by
specific deliberate and known sized ventilation. Nit by random icy draughts.



The not so ideal thing is to jsut rely on underlay to stop
drafts and not have insulation - but it sounds like now is as good a
time as any to insulate it.

I think it's best not to insulate with anything non-permeable.

More complete rubbish.

If its permeable, the wind gets in and destroys the properties. You
don't go out in an icy wind with JUST a jumper on. You need a windproof
covering over it.


My advice to the OP is to disregard everything this idiot says. he
appears to have no clue about insulation, damp or heat loss whatsoever.

[The Natural Philosopher[_2_]]

Tabby wrote:
On Dec 20, 5:37 pm, Ronald Raygun
wrote:
Tabby wrote:

Don't block the vents, unless you want the whole floor structure to
slowly rot away. The ideal thing t do is lift floorboards, fit
insulation between joists, add a VB over the top and re-lay the
boards.
I don't think that's a good idea. The whole point of under floor
ventilation is to eliminate stagnant air which promotes rot, which
affects not only the joists but the floorboards as well. If you're
going to wrap (even just the under-side of) the floorboards in a vapour
proof skin, you are *creating* pockets of stagnant air, defeating the
purpose of the ventilation, thereby putting the floor boards at risk.

You need to remember that a certain amount of draught is actually a
good thing, otherwise the room becomes too stuffy.

The not so ideal thing is to jsut rely on underlay to stop
drafts and not have insulation - but it sounds like now is as good a
time as any to insulate it.
I think it's best not to insulate with anything non-permeable. Use
underlay if you must, but with beautifully varnished floorboards, the
in-character thing is to have rugs, not wall-to-wall carpet. With rugs
you don't want an underlay that's too thick, or you'll keep tripping over
the rug edges. Worth a try is thin cardboard.

If you can identify any spots where the draught is excessive, caulking
the gaps with ordinary string may be effective.


The point of underfloor ventilation is to conduct away the damp that
evaporates from the earth below,

No, it is not. Or only in part.

once damp HAS evaporated, it gets very dry under a house. Oddly enough,
this is something to do with rain not falling on it.


If you have wet soil under a house, you have a drainage problem.


so RH doesnt rise high enough to
cause rot. If you insulate between the josits with no VB, you'd be
right, condensation and rot could occur. But with insulation and VB
above all is well.


correct.

NT

[The Natural Philosopher[_2_]]

Owain wrote:
On Dec 20, 12:31 pm, Jim wrote:
When we've decorated the room, I plan to get an underlayed berber
style carpet, which should prevent the draughts, but I'd like it to be
as cosy as possible for my children.

Hardboarding the floor would stop draughts between the boards and
would be fairly cheap and easy.


If carpeting, that and thick underlay and some sealant at the edges, is
a hole lot better than nothing at all.


I did that and it seemed to be about three times better.

Owain

[geraldthehamster[_2_]]

On 21 Dec, 12:59, The Natural Philosopher
wrote:
Mike Tomlinson wrote:
In article
s.com, Jim writes

That is to say, fix all the floorboards, then lay celotex/kingspan
(I'll have to look those up), then foil tape on top of that, and then
let the fitters lay underlay and carpet ontop of that?

Celotex is a foil-backed insulation mat, about an inch thick. *It
wouldn't stand up to being walked on, even with underlay and carpet on
top. *It's used for things like insulation between the roof joists
during a loft conversion, for example.

I don't agree with TNP here. *There would be some heat loss through the
floor, but not much, certainly not worth the effort of following his
suggestion of lifting the boards and fitting celotex between the joists,
then re-laying.

Do the calculations before you make such opinions.

Would you want a wall the size of your floor, cosnsisting of leaky
floorboards just covered with a carpet and underlay with a -5C 15mph
wind the other side?

yet a well vented underfloor space is just that.

Compared with a solid floor, where the ground itself acts as an
insulator, suspended wood is a complete heat loss disaster area
especially when its well ventilated.
.

* *As others have said, you'd also be creating pockets of

stagnant air between the celotex and the floorboards.

The celotex is flush with the top of the boards.

BUT creating pockets if stagnant air is precisely what an insulation
material does anyway, so its a silly thing for you to say, twice over.



My opinion.- Hide quoted text -

- Show quoted text -- Hide quoted text -

- Show quoted text -

I agree with all of the above.

Some have mentioned a vapour barrier but I'm not convinced this is
essential within a floor. Moisture in the air underneath will be
carried away by the ventilation. If moisture in the warm air in the
room was going to condense into the floor, that would be more likely
in a colder uninsulated floor. I just don't think condensation is an
issue in either case, if under-floor ventilation is present. Though as
it happens, if you use foil-backed Celotex or Kingspan you'd have a
pretty good vapour barrier in any case.

Cheers
Richard

[The Natural Philosopher[_2_]]

geraldthehamster wrote:
snip brillaint post


I've had three winters here now and dealt with a lot of the other
insulation issues that the house has - I'm convinced now that a major
part of the cold feel that is left is down to the floors. Especially
when outside is minus fifteen. I've yet to hear anyone say they
insulated their floor, but considered it a waste of time. You can't
build anything new without insulating the floor...


+100
also my main gripe is that I wish I had insulated my floors MORE

In windy weather they lose a LOT of heat despite 2" of polystyrene.

So if anyone is laying a slab, or redoing floors, insulate to the max.
You wont regret it.


Cheers
Richard

[Stuart Noble]

also my main gripe is that I wish I had insulated my floors MORE

In windy weather they lose a LOT of heat despite 2" of polystyrene.

So if anyone is laying a slab, or redoing floors, insulate to the max.
You wont regret it.

So you went for Jablite then? They say it's a minimal fire risk on the
ground floor

[Stuart Noble]

The easiest way to insulate is probably to use space blanket, which is
a roll insulation encapsulated in plastic to avoid mess. It is rolled
out between the joists and supported on netting or similar. My problem
with this is that the standard size is 370mm wide, and assumes that
your joists are at 400 centres, whereas mine, annoyingly, are at 430
centres, so I'd have a gap. This leaves me the option of using
messier, unencapsulated roll insulation, or what I'll probably do
which is buy seconds of 50mm Kingspan, cut to size and fix in place
with PU foam.


Rockwool slabs are less messy than the rolls. 1200x600 but as easy to
cut as Celotex

[The Natural Philosopher[_2_]]

stuart noble wrote:

also my main gripe is that I wish I had insulated my floors MORE

In windy weather they lose a LOT of heat despite 2" of polystyrene.

So if anyone is laying a slab, or redoing floors, insulate to the max.
You wont regret it.

So you went for Jablite then? They say it's a minimal fire risk on the
ground floor

It certainly is under 5 " of screed and with a further 6" of concrete
underneath ;-)

Sadly I was required to have a suspended CONCRETE floor,. which is OK
but why they insisted it be VENTED is beyond me.

It came in handy though to make vents for the solid fuelled fires and
the aga tho :-)

But I suspect the heat calcs were done on the basis of a solid slab:
with venting it wasn't enough.Some parts of the floor are distinctly icy
near where the outside vents are.

[The Natural Philosopher[_2_]]

stuart noble wrote:

The easiest way to insulate is probably to use space blanket, which is
a roll insulation encapsulated in plastic to avoid mess. It is rolled
out between the joists and supported on netting or similar. My problem
with this is that the standard size is 370mm wide, and assumes that
your joists are at 400 centres, whereas mine, annoyingly, are at 430
centres, so I'd have a gap. This leaves me the option of using
messier, unencapsulated roll insulation, or what I'll probably do
which is buy seconds of 50mm Kingspan, cut to size and fix in place
with PU foam.


Rockwool slabs are less messy than the rolls. 1200x600 but as easy to
cut as Celotex
Not very effective when not in a sealed cavity with lots of 'stagnant
air' though.

Got that in my walls, till I closed all the cracks, walls were icy.
Stopping airflow was the key to making it work.

[Tim Watts]

On 21/12/10 15:21, The Natural Philosopher wrote:
geraldthehamster wrote:
snip brillaint post


I've had three winters here now and dealt with a lot of the other
insulation issues that the house has - I'm convinced now that a major
part of the cold feel that is left is down to the floors. Especially
when outside is minus fifteen. I've yet to hear anyone say they
insulated their floor, but considered it a waste of time. You can't
build anything new without insulating the floor...


+100
also my main gripe is that I wish I had insulated my floors MORE

In windy weather they lose a LOT of heat despite 2" of polystyrene.

So if anyone is laying a slab, or redoing floors, insulate to the max.
You wont regret it.


Cheers
Richard

Slabs over air are a ******* - had a flat with the car port under my
floor and 2" (guess) of polystyrene was still useless.

However, my current floors on slabs on earth with zero ventilation
aren't that bad - 12-20mm marmox on top in the bedrooms and bathroom
leave a most satisfactory floor that you can lie on in complete comfort.

--
Tim Watts

[Mike Tomlinson]

In article
s.com, geraldthehamster writes

the most common is a rigid foam board, usually foil backed, that comes
in sizes from one inch up to - actually I don't know, but certainly
more than seven inches. It's not a mat that you can lay on top of
floorboards and fix carpet to.

Um, that's exactly what I said.

--
(\__/)
(='.'=)
(")_(")

[harry]

On Dec 21, 5:20*pm, The Natural Philosopher
wrote:
stuart noble wrote:

also my main gripe is that I wish I had insulated my floors MORE

In windy weather they lose a LOT of heat despite 2" of polystyrene.

So if anyone is laying a slab, or redoing floors, insulate to the max.
You wont regret it.

So you went for Jablite then? They say it's a minimal fire risk on the
ground floor

It certainly is under 5 " of screed and with a further 6" of concrete
underneath ;-)

Sadly I was required to have a suspended CONCRETE floor,. which is OK
but why they insisted it be VENTED is beyond me.

It came in handy though to make vents for the solid fuelled fires and
the aga tho :-)

But I suspect the heat calcs were done on the basis of a solid slab:
with venting it wasn't enough.Some parts of the floor are distinctly icy
near where the outside *vents are.

Radon?

[RobertL]

On Dec 20, 12:31*pm, Jim wrote:
I plan to redirect our ground floor front room next year.

Currently, the walls are unplastered, and we've rewired so floorboards
are loose, so any option is possible at this point.

My question is what, if anything to do about draughts from under the
floor.

The house is Victorian, and slightly raised with large cavities under
the floor-boards. There is also a metal decorated air-grill at the
front of our house which ventilates the space under this room.


We were in the same situation and I didn't put celotex under the
floor; I wish I had done. We did fill the gaps between the
floorboards using a V section platic strip designed for the purpose.
That helped a lot.

My advice: do a proper insulation job between the joists and leave the
ventilation under there alone. Remember to get building control
approval (it's covered by Part L).

Robert

[RobertL]

On Dec 21, 6:07*am, Mike Tomlinson wrote:
In article
s.com, Jim writes

That is to say, fix all the floorboards, then lay celotex/kingspan
(I'll have to look those up), then foil tape on top of that, and then
let the fitters lay underlay and carpet ontop of that?

Celotex is a foil-backed insulation mat, about an inch thick. *

For the OP's situtaion it will need to be about 100mm thick to meet
building regs. The required thickness depends on the (exposed
perimiter)/area of the floor. take a look he
http://www.insulation.kingspan.com/uk/pdf/tf73.pdf to see how thick it
needs to be.

Fllorboard gap filler we used was called "gapseal" and it worked
well.

Robert

[Stuart Noble]

On 22/12/2010 09:46, RobertL wrote:
On Dec 20, 12:31 pm, wrote:
I plan to redirect our ground floor front room next year.

Currently, the walls are unplastered, and we've rewired so floorboards
are loose, so any option is possible at this point.

My question is what, if anything to do about draughts from under the
floor.

The house is Victorian, and slightly raised with large cavities under
the floor-boards. There is also a metal decorated air-grill at the
front of our house which ventilates the space under this room.


We were in the same situation and I didn't put celotex under the
floor; I wish I had done. We did fill the gaps between the
floorboards using a V section platic strip designed for the purpose.
That helped a lot.

My advice: do a proper insulation job between the joists and leave the
ventilation under there alone. Remember to get building control
approval (it's covered by Part L).

Sod that

[The Natural Philosopher[_2_]]

harry wrote:
On Dec 21, 5:20 pm, The Natural Philosopher
wrote:
stuart noble wrote:

also my main gripe is that I wish I had insulated my floors MORE
In windy weather they lose a LOT of heat despite 2" of polystyrene.
So if anyone is laying a slab, or redoing floors, insulate to the max.
You wont regret it.
So you went for Jablite then? They say it's a minimal fire risk on the
ground floor
It certainly is under 5 " of screed and with a further 6" of concrete
underneath ;-)

Sadly I was required to have a suspended CONCRETE floor,. which is OK
but why they insisted it be VENTED is beyond me.

It came in handy though to make vents for the solid fuelled fires and
the aga tho :-)

But I suspect the heat calcs were done on the basis of a solid slab:
with venting it wasn't enough.Some parts of the floor are distinctly icy
near where the outside vents are.

Radon?
In SUFFOLK?

[geraldthehamster[_2_]]

On 22 Dec, 10:32, stuart noble wrote:
On 22/12/2010 09:46, RobertL wrote:



On Dec 20, 12:31 pm, *wrote:
I plan to redirect our ground floor front room next year.

Currently, the walls are unplastered, and we've rewired so floorboards
are loose, so any option is possible at this point.

My question is what, if anything to do about draughts from under the
floor.

The house is Victorian, and slightly raised with large cavities under
the floor-boards. There is also a metal decorated air-grill at the
front of our house which ventilates the space under this room.

We were in the same situation and I didn't put celotex under the
floor; *I wish I had done. * We did fill the gaps between the
floorboards using a V section platic strip designed for the purpose.
That helped a lot.

My advice: do a proper insulation job between the joists and leave the
ventilation under there alone. *Remember to get building control
approval (it's covered by Part L).

Sod that- Hide quoted text -

- Show quoted text -

Seconded. Celotex is expensive enough without unnecessary fees.

Cheers
Richard

[fred]

In article
,
RobertL writes
On Dec 21, 6:07*am, Mike Tomlinson wrote:
In article
s.com, Jim writes

That is to say, fix all the floorboards, then lay celotex/kingspan
(I'll have to look those up), then foil tape on top of that, and then
let the fitters lay underlay and carpet ontop of that?

Celotex is a foil-backed insulation mat, about an inch thick. *

For the OP's situtaion it will need to be about 100mm thick to meet
building regs. The required thickness depends on the (exposed
perimiter)/area of the floor. take a look he
http://www.insulation.kingspan.com/uk/pdf/tf73.pdf to see how thick it
needs to be.

That's pointing to Kingspan Thermafloor which is polystyrene, PIR foam
thickness should be about half of that for the same thermal properties
so say 50mm.
--
fred
FIVE TV's superbright logo - not the DOG's, it's ********

[fred]

In article
,
RobertL writes
Remember to get building control
approval (it's covered by Part L).

There is no requirement to gain approval for additional insulation where
there is no change to the structure.
--
fred
FIVE TV's superbright logo - not the DOG's, it's ********

[Tabby]

On Dec 21, 1:07*pm, The Natural Philosopher
wrote:
Tabby wrote:
On Dec 20, 5:37 pm, Ronald Raygun
wrote:
Tabby wrote:

Don't block the vents, unless you want the whole floor structure to
slowly rot away. The ideal thing t do is lift floorboards, fit
insulation between joists, add a VB over the top and re-lay the
boards.
I don't think that's a good idea. *The whole point of under floor
ventilation is to eliminate stagnant air which promotes rot, which
affects not only the joists but the floorboards as well. *If you're
going to wrap (even just the under-side of) the floorboards in a vapour
proof skin, you are *creating* pockets of stagnant air, defeating the
purpose of the ventilation, thereby putting the floor boards at risk.

You need to remember that a certain amount of draught is actually a
good thing, otherwise the room becomes too stuffy.

The not so ideal thing is to jsut rely on underlay to stop
drafts and not have insulation - but it sounds like now is as good a
time as any to insulate it.
I think it's best not to insulate with anything non-permeable. *Use
underlay if you must, but with beautifully varnished floorboards, the
in-character thing is to have rugs, not wall-to-wall carpet. *With rugs
you don't want an underlay that's too thick, or you'll keep tripping over
the rug edges. *Worth a try is thin cardboard.

If you can identify any spots where the draught is excessive, caulking
the gaps with ordinary string may be effective.

The point of underfloor ventilation is to conduct away the damp that
evaporates from the earth below,

No, it is not. Or only in part.

once damp HAS evaporated, it gets very dry under a house. Oddly enough,
this is something to do with rain not falling on it.

If you have wet soil under a house, you have a drainage problem.

* so RH doesnt rise high enough to

cause rot. If you insulate between the josits with no VB, you'd be
right, condensation and rot could occur. But with insulation and VB
above all is well.

correct.



NT

The reason to elevate timber floors is to avoid damp from the ground.
Timber floors laid straight on ground, only occasionally encountered,
tend to rot.


NT