Insulation for suspended wooden floor
Discussion
Steffan said:
A structural engineer said to me years ago when we were refurbing a Victorian House with galloping dry rot ' You never see dry rot in a barn. Its because they are so well ventilated, no pools of still air.'
He was substantially correct: ventilation is the lifeblood of preserving timber in floors.
It's the space below the floor that needs venting not the floor joists.He was substantially correct: ventilation is the lifeblood of preserving timber in floors.
We have a 1930`s house on a hill with a void underneath of between 8-14ft, I filled the space underneath the floor in between the joists with expanded foam/urethane/celotex type board that I got for £2 per 10x4ft sheet from a recycling place near me.
I made sure all the air bricks were clear of any blockages etc which should allow enough flow to stop any rot.
It was well worth doing and i`m going to get some more and replace the rockwool in the loft with the same.
Ray
I made sure all the air bricks were clear of any blockages etc which should allow enough flow to stop any rot.
It was well worth doing and i`m going to get some more and replace the rockwool in the loft with the same.
Ray
mk1fan said:
cuneus said:
I asked about 120mm boards.
How does wool work in a loft ?
I know. I just happened to buy a sheet of 100mm at the w/e so knew the price.How does wool work in a loft ?
Wool works in the loft because the plasterboard / lathe and plaster is a closed surface. Unlike floorboards that have gaps between them [that open and close].
If you were to lay wool over just lathes then it wouldn't work as well.
Edited by mk1fan on Thursday 3rd November 19:07
ssray said:
We have a 1930`s house on a hill with a void underneath of between 8-14ft, I filled the space underneath the floor in between the joists with expanded foam/urethane/celotex type board that I got for £2 per 10x4ft sheet from a recycling place near me.
I made sure all the air bricks were clear of any blockages etc which should allow enough flow to stop any rot.
It was well worth doing and i`m going to get some more and replace the rockwool in the loft with the same.
Ray
What thickness of boards did you go for?I made sure all the air bricks were clear of any blockages etc which should allow enough flow to stop any rot.
It was well worth doing and i`m going to get some more and replace the rockwool in the loft with the same.
Ray
cuneus said:
Can you blow through 170mm of wool ?
Me personally, no. But then again I can't blow soot out of a chimney. Something a gentle breeze can do with ease. I have felt air coming though thick wool insulation. It's permiability is one reason why US codes require internal and external vapour barriers.At the end of the day if the OP were going to be sheeting over the floor and then laying a laminate or parquet or tiles then using wool would be fine (assuming there was sufficient joist depth) as the warm side is closed off by the sheeting. But their not doing that. They are fitting old floor boards for the period look. These are going to shrink and move making loads of gaps.
So, in this case, using insulation boards is the better and more efficient option.
Edited by mk1fan on Thursday 3rd November 19:51
smn159 said:
What thickness of boards did you go for?
100mm finishing off the job next week, because i cant get board in between the hot water pipes and the floor so i will be using space blanket on those bits and expanding foam on the end bits-only on brick and not covering up the wooden joists with it.Ray
cuneus said:
Exhale ~ 15 mph
Gentle breeze = 11.5 mph max
and how would that happen in the underfloor space ?
Really? How would a breeze enter an externally ventilated floor void?Gentle breeze = 11.5 mph max
and how would that happen in the underfloor space ?
We'll have to agree to disagree. As I've previously said using 'wool' insulation to insulate a floor is workable in the right circumstances. The OPs, imho, are not the right circumstances.
russ_a,
I refer to the last sentence in my first post on this thread http://www.pistonheads.com/gassing/topic.asp?h=0&a...
That is arwful and ill thought out work you've photographed there.
Edited by mk1fan on Friday 4th November 13:22
mk1fan said:
I refer to the last sentence in my first post on this thread http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Agree with you on that one.ill thought out.
Some DIYers though, do take on/seek advice from those who do know better.
Yeap, I wished I hadn't had done it but it has stopped the breeze blowing through the carpet!
Lots of threads on DiyNot.com recommending netting and wool over boards due to ventalation.
Read a few posts where peoples joists had rotted in the roof space and floor. A couple of people using boards had commented that when they spill a drink on the floor it just sits on the boards and doesn't evaporate.
As we are fitting a solid wood floor glued to the floor, was told wool and netting was best. Though my builder refused to do it!
You live and learn
Lots of threads on DiyNot.com recommending netting and wool over boards due to ventalation.
Read a few posts where peoples joists had rotted in the roof space and floor. A couple of people using boards had commented that when they spill a drink on the floor it just sits on the boards and doesn't evaporate.
As we are fitting a solid wood floor glued to the floor, was told wool and netting was best. Though my builder refused to do it!
You live and learn
Edited by russ_a on Friday 4th November 22:11
hairyben said:
Have just done the same- 6" of celotex, 3" in the joist as I needed the top inch for UFH pipes and 3" again below. 4" would be more than ample I'd have thought, and fit in the joist nicely.
Look online for C&H insulation, v keen prices
Thread resurrection! as have a question for you Look online for C&H insulation, v keen prices
Im guessing your existing joists are like mine (4x2). How did you support the additional 3" below the joists?
And did you put a screed on top of the UFH pipes too? if so did you need to strengthen the joists any further for the weight of the screed?
Thanks
Edited by hyphen on Wednesday 15th February 12:44
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