Foam Roofing Insulation Questions

A question about : Foam Roofing Insulation Questions

We have an edwardian house with a roof that is past it's best, I have seen the ads for spraying the inside of the roof with polurethane foam which supposedly strengthens the tiles and stops slippage where the nails have decayed. My questions are, how much roughly are there good/bad firms out there and most importantly when we come to sell (say five years time) will the surveyor fall out of the loft with laughter!!!!

If anyone can give advice I would appreciate it

Best answers:

• Please see these previous threads I've posted on :
  https://forums.moneysavingexpert.com/...highlight=roof
  https://forums.moneysavingexpert.com/...highlight=roof
  Hope this is enough to stop you ruining your roof and wasting a fortune !
  rob
• From Institute of Historic Building Conservation Discussion Board Roofing foam
  My house is listed and prior to my moving in a non-porous roofing felt was put under the tiles. This caused more damage to the original timbers in three years than they experienced over the previous 300yrs. Roof timbers have to be ventilated or the damp air gets trapped and the timbers rot or become tasty to woodworm etc.