Advice on having garage/workshop asbestos roof spray foamed.

[netlon]

Hi there. I have a corrugated asbestos roof on my garage/workshop which is past its best. It is a fair size (23ft x 12ft) and there is not access to all sides. I am contemplating removing it and replacing with bitumen type sheets. However, I have also thought about leaving it in place and having the underside sprayed with polyurethane foam to help with insulation. Does anyone have any ideas or advice. TIA

 

[whybob71]

I strongly suggest to use a polyurethane foam to insulate the roof. Removing the old roof require a specialized (and very expensive) work (actually in my country is prohibited to do it yourself, even the polyurethane foam application) and is quite dangerous for your health

 

[BradNaylor]

In my old workshop I had a corrugated metal roof without any insulation. I had it sprayed with the foam stuff and it was fantastic. Not only did it insulate and eliminate condensation but it 'tied' the roof panels together so they didn't move or rattle.

Recommended.

Dan

 

[OPJ]

Are you doing anything to stop the leaks? I'm only assuming that yours leaks because I have the same kind of roof covering and when it rains outside, it starts to rain inside too.

Someone told me ages ago that you should start by applying sealant/something around the fixings on the outside? I still haven't tried this yet!

Actually, although you may have to pay £500 or so to have it removed (if you were to go down that route) I've heard that some councils will arrange it free of charge - it may be worth a phone call.
I also understand there are two types of this covering, one being safer than the other? I'm not sure. I think one's cement-based?

I was planning on doing my roof as well this year but... What kind of summer will we have? Money! Time... I'm interested to see how the foam works for you. Don't forget to fill any gaps around the soffit (?) area behind the wall plates, if you have a pitched roof construction (sounds as though it's a flat roof on your garage though).

 

[netlon]

My roof is pitched and I have had a few leaks. Some of the panels cracked down the length so I pushed some polyurethane glue into the cracks with a filler knife, then painted over it with 2 or three coats of Johnstones bitumin paint from Screwfix. This was all done from the inside taking some basic safety precautions and I DIDN'T scrape the surface before sealing & painting. Up to now, I've had no problems with leaking, only condensation. Btw, what did you pay to have the roof sprayed?

 

[OLD]

Have a look at:-
http://www.foamseal.co.uk/
and
http://www.bufca.co.uk/

 

[OPJ]

Well, it looks more expensive than I thought it'd be - but it's a damn sight cheaper than having to overhaul the entire roof, even if you're competent enough to cut and fix the new rafters/whatever yourself!

I definitely gonna give this a try in the summer. And with the left-overs, I guess I could also do the up-and-over garage door. :wink:

Does this add any considerable amount of weight to the roof, at 1" thick?

What about risks, such as fire hazards? There's no way I could board it over with the bizzare design my garage roof has currently! :?

I'd like to spend more money and do it all over again, starting from scratch. But, I am a student. And, where I use this as a workshop now, whenever we move, it'll probably only be a storage garage for future occupants.

 

[netlon]

Thanks for those links. The roof is supported by metal frames which is one reason its a bit of a pain to sort out. My overall plan is to create a 'room' within the garage with stud walls faced with plywood and insulate it. I may just paint the whole underside of the roof with the bitumin paint and create a plywood ceiling under the metal roof supports. I'll try and post some pics if I can.

 

[Escudo]

I say, that's a rather smart pipe in your avatar, looks like a straight billiard.

Cheers, Tony.

 

[OPJ]

Does this foam need to be covered over afterwards, to prevent the risk of fire or some kind of combustion? I hope not, because my garage roof is so poorly built there's no way I could fit even a single sheet to the rafters without removing and replacing the whole thing.

Good idea about the walls; it'll insulate your work space and timber is a heck-of-a-lot easier to screw in to than masonry! If you're looking to save on cost, you should find that OSB sheets (oriented strand board) is about half the price of a similar sheet of ply. It's good stuff and I plan to do the same to my garage-cum-shop at some point.

 

[Digit]

Polyurethane foam
The non-toxic and odourless polyurethane foam spray is suitable for almost all situations. Being British Standard Class1fire rating it meets Building Regulations for use in public buildings. The polyurethane foam is 95% closed cell meaning that it maintains the breathing properties of roof timbers so no damp can be trapped by Rooftherm's foam.

Does that help?

 

[OPJ]

Very helpful indeed, thank you!

Sorry, I completely ignored the two links before.