The complete rear section of the 2nd floor of our house is timber framed and is very cold in the winter. It consists of foil backed plasterboard, a thin covering of mineral wall within a 100mm cavity, membrane and then weatherboard.
We are going to replace the weatherboard with tiles and fill the 100mm cavity with insulation. We are currently thinking of retaining the foil back plasterboard > 100mm Insulation boards > 20 mm OSB or wood fibre boards attached to the outside of the frame > breathable membrane > batten and tile.
Can anybody advise if this construction would be OK and breathable? OSB or wood fibre insulation boards? I was thinking of a foil based breathable membrane are these worth it over the tyvek types?
I am a complete newbie so please excuse an errors/stupid questions.
Thanks
tony
14 Oct 2009, 6:59 PM
If you do that you will be in contravention of part L1b of the building regulations
I think that you should try to achieve a much lower U value while you have the opportunity.
Make sure that the new bits are all air tight, and i would not use a foil breather -- newspaper will do!
