is there such a thing as too much insulation you can have in a loft someone recently told me too much can make the loft sweat but I can't see how this is possible?
Thanks
Wendy
Thanks
Wendy
Too much insulation
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Thank you I've just had the loft re-felted and want to improve the insulation as much as possible. My loft has the fibre insulation down both sides and then was already boarded down the middle. I was planning on adding extra fibre insulation over the existing however do have a query with this, my bathroom has down lighters that I can't afford to replace yet I saw somewhere the best thing is to put an upturned terracotta flower pot with a hole in the bottom over the light and then insulation around the pot, is this ok?
I also don't want to lift the existing boards as my loft is massive so was thinking of putting some insulation boards down (I've seen some jabalite ones in B&Q on offer) or using something like celotex and then putting more boards on top so we can continue to walk on them and store things in the loft. What do you think?
Sorry for all the questions I'm a very inexperienced female lol
I also don't want to lift the existing boards as my loft is massive so was thinking of putting some insulation boards down (I've seen some jabalite ones in B&Q on offer) or using something like celotex and then putting more boards on top so we can continue to walk on them and store things in the loft. What do you think?
Sorry for all the questions I'm a very inexperienced female lol
I think you mean the roof re-felted. If not you might need to explain what you have had done.
Ask in the electrical section about the lights and covering them, or even search in that forum, just put down lighter (and try again with downlighter) and insulation in the search box. I'm sure it's been asked before. You might need the advice of a sparky, on site, to identify your down lighters and recommend a product.
You can certainly add more insulation in the rest of the loft. It ought to be done at right angles to existing, going across ceiling joists, assuming you only have 100mm or so.
Your additional boards ought to be fixed to make them safe. Can you do this?
This is an excellent site for reference:
https://www.nia-uk.org/consumer/understanding-insulation/faqs/
It gives minimum thickness recommendations as well.
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Sorry I mean the roof has been refelted, all tiles removed and felt laid new baton and tiles put back on.
Yes we should be able to fix new boards down will using the insulation boards make much of a difference?
Yes we should be able to fix new boards down will using the insulation boards make much of a difference?
I'm guessing that your exisitng ceiling joists are 100mm deep, therefore you'll only have 100mm insulation under the boards.
The recommended is 270mm, but that is based on rockwool or similar, so yes, it will make a difference.
Ask in B&Q, or wherever you're buying, for the equivalent of 270mm rockwoll, and as you already have 100mm you can fit thinner board insulation.
This quote from theoldun illustrates the difference:
So I would suggest 100mm celotex, even 90mm celotex, along with your existing 100mm rockwool under the boards, will achieve more than the recommended minimum.Hi,
Can anyone tell me please what the difference is between Celotex insulation and fibre wool insulation?
In a nutshell.
To achieve current u value of 0.16Wm2/K
270mm thick Earth wool, Rockwall, Fibreglass with a lambda of 0.044 W/mk will give R value of 6.13m2k/W and U value of 0.16Wm2/K
140mm thick Celotex with a lambda of 0.022 W/mK will give a R value of 6.36m2k/W and will also give a U value of value of 0.16Wm2/K
With the exception of sheeps wool celotex is approx twice as efficient as earth, rock or glass
Fire risk and acoustics do not come into the equation.
Regards oldun
NB, to look up the oiginal quote, click on the little 'up' arrow alongside the "user's name said"
Hi thank you for explain this to me, yes it's breathable membrain that's been used. Sorry I don't know the technical names of stuff
I'm guessing that your exisitng ceiling joists are 100mm deep, therefore you'll only have 100mm insulation under the boards.
The recommended is 270mm, but that is based on rockwool or similar, so yes, it will make a difference.
Ask in B&Q, or wherever you're buying, for the equivalent of 270mm rockwoll, and as you already have 100mm you can fit thinner board insulation.
This quote from theoldun illustrates the difference:
So I would suggest 100mm celotex, even 90mm celotex, along with your existing 100mm rockwool under the boards, will achieve more than the recommended minimum.Hi,
Can anyone tell me please what the difference is between Celotex insulation and fibre wool insulation?
In a nutshell.
To achieve current u value of 0.16Wm2/K
270mm thick Earth wool, Rockwall, Fibreglass with a lambda of 0.044 W/mk will give R value of 6.13m2k/W and U value of 0.16Wm2/K
140mm thick Celotex with a lambda of 0.022 W/mK will give a R value of 6.36m2k/W and will also give a U value of value of 0.16Wm2/K
With the exception of sheeps wool celotex is approx twice as efficient as earth, rock or glass
Fire risk and acoustics do not come into the equation.
Regards oldun
NB, to look up the oiginal quote, click on the little 'up' arrow alongside the "user's name said"
Is the Celotex OK on top of the rockwool?
No there's fibre type insulation and then loft boards, I was thinking of adding the celotex on top of the loft boards and then adding more loft boards so it can be walked on
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