I live in a relatively modern house with the typical prefab roof trusses. It has 4" fibre glass insulation, and I've boarded much of the area for storage. I'm looking at upgrading the amount of insulation but I can't just use thicker insulation without building up the trusses in some way. Is there an alternative insulation material that I could use to replace the glass fibre that is significantly better ? Thanks Tony
"Tony B" wrote
If you are going to lift the boards anyway, there is also the option of insulation boards. Insulate in the normal way between the joists, lay insulation board across the joists and put back your boarding. I put some down recently - 55mm thick. As it was only a small area I didn't look at the insulation value compared to the standard fluffy stuff. This is the stuff
Phil
Hi, I am doing this by filling the area under the boarded section with
50mm. expanded foam insulation which comes in 1200x2400mm. sheets. Most builders' merchants keep these under different names like Quinntherm, Ecotherm, Kingspan, Celotex...I expect they have similar specs. I pick them up and cut them with a hand saw to fit into the car and cut further when in the loft. You can compare the equivalent specs to glass fibre to see what you are getting and whether it is necessary to build up the joists to raise the floor to accommodate more...usually kept in 50mm and 25mm. thicknesses. Some keep it in smaller sizes of board too. David G
You can also lay this type of insulation on to of existing loft boards, then add another layer of boards as required - approx 1500mm of depth is required to meet modern regs
They're going to have to start building houses with taller roofs.
1500mm?
Are there any materials which are superior to the standard glass fibre wool which could replace the existing 100mm and give better u values ? This would be simpler than building up the the floor level ?
Tony
Does seem a little generous doesn't it!
Andy
Rockwool is better, but...high performing foam gives great insulation for a thin sheet. Not cheap.
Yes, the Cellotex yellow PIR foam boards. Their web site is quite decent too, with all the numbers you need.
In lofts, you generally have the spare thickness to go with glasswool (unless boarding is an issue). Anywhere else, the better performance of the yellow foam almost always wins out. Don't mention the multi- layer foils or there will be an argument. 8-)
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