Spray foam roofing.. any experiences?

[Lulu75]

I'm probably going to have to replace the roof on my house which is reaching the end of its natural life.  I've seen adverts for spray foam insulation which claim to insulate and bond together the tiles removing the need for traditional re-roofing.  Has anyone got experience of having this done?  It's supposed to be quicker and cheaper, is it too good to be true?

Thanks

[gem_mother]

We had it done about 3 years ago.  Our house is 100 years old and we were getting slates slipping fairly regularly because of nail fatigue.  It was done in  a day and while the inside appearance wasn't as tidy as it looks in the advert we are happy with it. 

We had the lead in a valley replaced at the same time and the only trouble we've had since was with this - and for this reason and the problems we had getting somebody back to fix it I wouldn't recommend the particular firm we used. 

The insulation properties seem good - we are usually the last house in the street to lose snow/ice from the roof.

The loft is a lot cleaner since we had it done - we used to get cobwebs and bits falling everywhere.

We haven't had any more slates slip and we've had some bad storms since then.

Finally I think it cost about a fifth of the price we were told it would cost for a re-roof.  We got 3 firms to give us a quote and went for the middle one.  There was quite a big difference in the prices quoted but the fact that we were having the valley fixed and a flat bit of roof over the bay window replaced at the front meant that things weren't straightforward.

[jake-the-peg]

This from SPAB

Q. Are bitumenised treatments or spray-on foams a good idea?

A. No, experience shows bitumen-coated fabric on the outside of roofs or spray-on coatings underneath can be a false economy, and cases have been reported of serious damage resulting to the structure. Such treatments prevent proper inspection, hinder the re-use of slates or tiles and, by reducing ventilation, increase the risk of timber decay.

http://www.spab.org.uk/publications_Q&A_RoofMaintenance.html

[chantelo]

There are 2 routes you can take: You can get an installer to spray the foam on for you or you can choose to do it yourself.

There are DIY packs available, but you need to follow the instructions to the letter!!!!

You could try http://www.spray-insulation.co.uk/diy.htm
There is a spraying guide on there that tells you a bit more about it, but as previously said, if you don't follow the instructions (like all things), you will get it wrong.