I need to source a breather membraine for walls. Im converting my garage using the Celotex "garage conversion" guide and I have to fit a breather membrane against the single skin brick before the celotex goes on. I have contacted Celotex and they say use Tyvek House wrap but thats only available in massive rolls for megga £££, can I just use a roofing breather membraine? is that the same thing as its loads cheaper. P.S Im doing this legit with full building regs Im just concerned that BC will see roofing membraine written all over it and ask me to rip it out.