Corrugated asbestos/cement garaging roofing

[nitecard]

I have a double length garage with asbestos/cement corrugated pitched roof.

The original ridge which is steel has corroded to nothing in many places and needs to be replaced as the garage is open to the elements in those places.

I was planning on using bitumen ridge tiles made by various people, also Wickes do them.

The roof itself is in good condition.

I was goung to use a sterling board crawler, the old ridge can be removed from inside as it is bolted through, worst way the bolts can be ground off and the ridge pushed off through the gap.

I've read here that people have said that they would not go onto the roof even with a crawler board, I had always assumed it would be ok.

Has anybody has experience of tackling this job, I really don't want to replace the roof as it would cost £1000s.

I would appreciate any comments.

Thanks in advance.

[Michael Chare]

If the roof is asestos you do need to be very careful. It would be worth checking if that really is the case. There are specialist asbestos removers and they might give your a free quote and tell you if the roof is made using asbestos.

[Tricky Dicky]

Cement/asbestos sheets do degrade over time, when we demolished our concrete garage I removed the flat roof of corrugated cement asbestos sheets by using a multi tool to cut the fixing nails from below. Many of the sheets simply split along the corrugations and few if any came off without bits breaking off. I am really glad I did not even consider crawling on top even with planking to span the joists.

Richard

[Andrew]

'Free' quote followed by stupid price to remove and dispose.!

[The Natural Philosopher]

Utter bollocks.

Asbestos risk is totally overblown, and cement asbestos totally so.

The risk is asbestos fibres in the lungs. Over long periods of time. They are bound well in cement board and you aren't using angle grinder.

If you aren't a smoker and you can cough the lungs will clear the shit out.

[nitecard]

Thanks Michael

The more I read the more worrying it becomes.

I wanted to avoid the expense as the roof is in good condition, just the ridge that needs replacing.

[charles]

Asbestos cement is not the samae s asbestos. It was a very commonly used building material in the '60s and 70's to my knowledge. I used it when building an extension in the early 70s. The Marley garage at this house also uses corrugated asbestos cement as its roofing material.

But on the original question, I imagine the steel ridge was/is structural. I can't see the roof staying up, let alone supporting your weight on a crawler if you remove it. Bitumen ridge tiles might keep the rain out, but they haven't any structural strength.

[tabbypurr]

just put some timber beams across supported on something else, add a board and hopefully you can access it.

RE asbestos fibres, if the sheet isn't disintegrating it's not releasing fibres.

NT

[charles]

There's still nothing to replace it.

[nitecard]

I don't think the ridge is structural, the panels are fixed to the steel angle trusses which are fixed to the top of the walls.

They are so rusted that if they had been structural the roof would have already collapsed!

[harry]

You can deal with asbestos cement yourself.

[harry]

You can lay a ladder along the corrugations making sure it spans the purlins supporting the sheets. Then if the sheets do crack the ladder will not fall.

[newshound]

Agree, but the ladder may give high local loadings increasing the risk of cracking. If you can get the ridge off in the first place, is it possible to get a sheet of stirling board or shuttering ply, put a substantial batten (75*75?) along one short edge, and then hook that along the top of the corrugated boards. You have the same protection from the purlins as in Harry's method. Remember that bitumen roofing is only rated for 10 years, it can last a bit longer, but modern steel ridge might be better. You fit the ridge by moving the crawler along, then do the final ridge section from one end. If it is a bit steep, put a few roofing battens on the top side of the crawler to give footholds.

[FMurtz]

Get an old person to remove it,(less time left to get problems.) :)

[Brian Gaff (Sofa 2)]

How well supported is it underneath. This material does go very brittle with age, just a shock or a foot can bugger it. I had my garage taken away as I was going to get it done up and turned into a workshop, but it had the sides made from the same material and I kicked it and my foot went through and cracked one panel from half way up to the bottom. So, I guess a bit of testing of it in a place where its not important might be prudent. I'd even be careful from the inside as the one I had had the ridge held on by a hook bolt witch hooked around a rod witch was bent to the roof pitch, and up close it was obvious that a couple of these had started small cracks in the asbestos, one assumes by tightening and loosening with heat over the years.

You may be fine, but do be careful. Can you not get new ridge covers made from metal these days? Brian

[Brian Gaff (Sofa 2)]

It will be from his description. Its asbestos powder in a cement cast into corrugated panels. That is what gave it its strength, but over the years it does tend to get minute cracks with frost and all that moss etc, and it can be very weak if stressed. a very large area is needed to spread the weight of a person as even if you don't go through, messing with it is going to make the life expectancy shorter, and the leakability higher. My old shed was like that. In the start I had to saw it, but in the end, grabbing a corner would break it off. Brian

[Brian Gaff (Sofa 2)]

Actually I did not find the latter the case some years back. They spend a few hours doing it double bagging them and stacked them carefully in a skip. That only left the rusty framework and I did see the terrible condition of this before it was taken down and it scared the heck out of me. How on earth it was still standing was a miracle! Brian

[Brian Gaff (Sofa 2)]

I'm sorry, but my and others experience has obviously not been yours. It depends very much on the age, stresses of the sheeting and the weathering though, and is not obvious unless you know what you are looking for. Brian

[Brian Gaff (Sofa 2)]

To be honest most asbestos in cement are particles, not fibres. I've sawn it with a jigsaw, but in the open many many years ago with no ill effects. Not sure I'd do it in an enclosed area. Asbestos is a mineral and is actually naturally occurring but obviously not in its purest form.

I had an uncle who died from asbestosis. Basically its fibres which do not break down caused lesions in his lungs gradually reducing the area available to take up and expel gasses from the blood. You basically suffocate. He got it working for Westland Helicopters on the fireproof wiring in cable looms which had to be installed in restricted areas but with no protection.

Brian

[Brian Gaff (Sofa 2)]

I wonder if access from a cherry picker might be possible then? Brian