Replacement for asbestos garage roof

My garage roof is currently leaking very badly. The garage was constructed circa 1970. It is constucted of concrete sections bolted together, I think it may be Marley? The roof is corugated sheeting, probably asbestos. I’ve had some quotes for replacing the roof and was wondering if anyone could offer any advice.

Quote 1

Remove the asbestos roof and replace with coralline corugated sheets. Also replace all the facias. £680.

Would this leave problems with condensation and is it a good deal?

Quote 2

Asbestos Garage Roof Repair Systems • Plastisol Colour Coated Steel
For Asbestos Garage Roof Repair the Plastisol Colour Coated Steel system is designed to be installed over an existing cement asbestos sheet roof therefore avoiding the costly removal by approved asbestos removal firms. The Plastisol colour coated STEEL SHEETS run the full length of the garage, the flashings are all made to measure for your particular garage. It is important to note that we supply CONTINUOUS length steel sheeting which do NOT have joins.

This looks great and the quote is £1000 but it is keeping the old asbestos roof in place.

Any advice would be much appreciated.

Its been over 40 years, rip the existing so you can inspect your wood decking and install new products like ice and water barrier etc. My advise is a full tear if you can avoid it; a “re-cover” is a last resort imo.

TarMonkey, I would bet there is no decking. I bet its space sheethed or fastened to purlings. The most reasonably priced way would be to screw plywood over that roof system & then install a new roof system from there. Metal roofing (steel) is cheaper per square than a shingle system so I would recommend that.


Tar, whats that supposed to mean? I believe what the h.o. is getting at is that he cannot afford the abatement company for removal of the asbestos roof system & he is asking us about other affordable options.

Well for one thing I would walk away before I would put plywood over any existing roofing. For another, you typically don’t “screw” down plywood unless you’re doing spot repair on “popping” decking because the shear strength of screws sucks compared to nails. So wrong application and wrong fasteners imo.

Actually most those old asbestos roof were nailed over a solid deck. :stuck_out_tongue:

If it is solid deck then you can shoot the plywood down, but use ringshank nails, not commons. If it is space sheathed? Screws would be way better. B/T/W Tar, screws have 8 times the holding power than nails. Thats why the safety harness securement devices have a million holes in them. Because OSHA wants you to fill every hole with a nail!

Tar Monkey is correct, screws don’t have the shear strength that nails do.
Screws are made out of much harder steel, as a result they tend to break under shear conditions rather than bend or slightly deform like the softer steel of a nail does.

Wow Axe! You just re-educated me.

If you suspect that asbestos is in your home, or on your property do not touch it or remove it. Call Access Asbestos Removal for all your asbestos removal needs we are licensed, insured and have over 10 years experience in the safe removal of asbestos across all Sydney areas.

Go to Google and type Access Asbestos Removal Sydney

Thanks… :smiley:

I still dont believe that nail comment. If that was the case,wouldn’t we be nailing down insulation board before rubbering? Not plating & screwing. Or what about a high quality screw like a stainless screw?

Insulation screws and plates are for uplift, as the insulation isn’t structural it doesn’t require any shear value. Stainless screws are generally softer than standard screws, as well.

So Patchup, what kind of screw would you recommend? The all weather screws that look like drywall screws but they’re coated?

Because screws have more holding power, think up and down, required for wind uplift.

Think of it this way. If you put a 12" screw between two cinder blocks laying down and hit it with a hammer what will it do? Break.

If you did the same with a similar nail what would it do? Bend.

Nails are softer, there for more flexible. If you ever get a bucket of 3" deck screws for screws and plates look for one that doesn’t have any thread. Now try and drive that in to 2X4 on edge. I bet it breaks before you can drive it all the way in.