Spray Foam Insulation
Discussion
Thinking of putting spray foam insulation into the roof of our property in an attempt to get around some of the issues regarding ventilating behind polystyrene type insulation due to attractive oak beams that we would like to leave exposed. Due to the nature of t eh foam i believe i do not need the 50mm air gap behind the insulation. We will be spraying directly onto the roof felt.
Was wondering if anyone had any experience of this and what the bonuses / pitfalls might be.
Also just spotted this? Does this mean i shouldn't be using any spray foam?
www.diysprayfoam.co.uk
Any advice gratefully received
Was wondering if anyone had any experience of this and what the bonuses / pitfalls might be.
Also just spotted this? Does this mean i shouldn't be using any spray foam?
www.diysprayfoam.co.uk
Any advice gratefully received
Edited by jjabennett on Monday 4th October 20:38
jjabennett said:
Thinking of putting spray foam insulation into the roof of our property in an attempt to get around some of the issues regarding ventilating behind polystyrene type insulation due to attractive oak beams that we would like to leave exposed. Due to the nature of t eh foam i believe i do not need the 50mm air gap behind the insulation. We will be spraying directly onto the roof felt.
Was wondering if anyone had any experience of this and what the bonuses / pitfalls might be.
Also just spotted this? Does this mean i shouldn't be using any spray foam?
www.diysprayfoam.co.uk
Any advice gratefully received
Was wondering if anyone had any experience of this and what the bonuses / pitfalls might be.
Also just spotted this? Does this mean i shouldn't be using any spray foam?
www.diysprayfoam.co.uk
Any advice gratefully received
Edited by jjabennett on Monday 4th October 20:38
website said:
VERY IMPORTANT LATE BREAKING NEWS INFORMATION
THE LATEST BUILDING REGULATIONS ON FIRE SAFETY AND THE REASON WHY WE HAVE DECIDED TO WITHDRAW OUR DIY SPRAY FOAM KIT RANGE FROM THE UK MARKET
With immediate effect we are withdrawing our complete range of DIY spray foam kits from sale due to changes in fire safety under the latest Building Regulations.
Downsides? I'm guessing it's not fireproof?THE LATEST BUILDING REGULATIONS ON FIRE SAFETY AND THE REASON WHY WE HAVE DECIDED TO WITHDRAW OUR DIY SPRAY FOAM KIT RANGE FROM THE UK MARKET
With immediate effect we are withdrawing our complete range of DIY spray foam kits from sale due to changes in fire safety under the latest Building Regulations.
Apart from that, sprayfoaming the underside of roof tiles is frowned upon by building inspectors due to breathability and condensation probs I think.
Edited by andy43 on Monday 4th October 20:46
Understand the issue about the fireproofing although the same website then goes on to offer a professional service that does comply with building regulations. However why the negativity regarding this solution?
Is there any other way to avoid the 50mm air gap between the felt and the insulation. Listed buildings will not let me lower the ceiling but i want ot get as much insulation in as possible.
Thanks
Is there any other way to avoid the 50mm air gap between the felt and the insulation. Listed buildings will not let me lower the ceiling but i want ot get as much insulation in as possible.
Thanks
m4ckg said:
you can get insulation on a roll thats about 8mm thick and has the same insulation values of 200mm of rockwool. ( I think ) not a cheap option though.
Yes that's right.. 
8mm of one material is equivalent to 200mm of another material.Even Celotex, the best known and widely accepted insulation pinnacle needs 150-165mm with a 50mm airgap. Most of the 8mm stuff isn't certified - although happy to accept it, if you can find some that is. They also wanted to change the certification tests for the multi-foils... hmmm...
To the OP : You could use multi-foil in addition to Celotex... Would you possibly be able to counter batten the tiles/roof covering off from the outside, to give a bigger ventilation gap? Might be worth asking your Listed Building Case Officer if they would be happy or willing to accept this. Of course you may well have asked this, or it might be a complete PITA.
Spray foam insulation just feels and seems wrong. It effectively bonds bits of the roof structure together in a way that they shouldn't be bonded. Parts of a roof will move and in your case probably more than others. Stopping it from doing that will cause problems, imho and then if you want to take remedial action to fix these problems you will be hindered by the spray foam stuff applied...
Don't.
And if you are even thinking of it on a listed building talk to the conservation officer first.
I'm unconvinced by the multifoils (it looks like the main benefit is airtightness and draught reduction which can be achieved with a sheet of polythene) although aerogel seems to get good reports - it has thermal conductivity of .013w/mK so you're looking at around 1/3 the thickness of rockwool for the same impact. Not cheap though - google Spacetherm for suppliers.
And if you are even thinking of it on a listed building talk to the conservation officer first.
I'm unconvinced by the multifoils (it looks like the main benefit is airtightness and draught reduction which can be achieved with a sheet of polythene) although aerogel seems to get good reports - it has thermal conductivity of .013w/mK so you're looking at around 1/3 the thickness of rockwool for the same impact. Not cheap though - google Spacetherm for suppliers.
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