Experience of repairing asbestos (or cement fibre board) sheet garage roof that leaks (in a block)

ThisIsWeird

pmartin86 said:

ThisIsWeird said:

20vt-rs said:

Thanks all for the feedback, had a local roofer out to take a look and says that it is leaking due to rubber grommets on the fixings being perished, and letting water through. I must say I am not fully convinced it is all that but I guess this could be contributing at least. I think replacing those and also sealing the overlap from the inside would go a long way, anything else to consider? Not leaking through the boards that we can see. Thanks.

Are you up for a bit of DIY?! Do you have ladders that could be strung across the roof so's to remove direct weight from it?

If so, you could eliminate the roofer's suspicion by wire-brushing each screw, and painting over it with Cromopol.

If this doesn't work, then on to the next cause :-)

Probably best NOT to take a wirebrush to an ageing asbestos roof...

Eek! Oops - post changed.

20vt-rs

Hi all - many thanks for your replies and suggestions. I am not very good at DIY, tend to make tings worse than fix!!! So will get a roofer to resolve this, I do get what Grenage says re the washers and peaks/troughs and I agree thats probably not the main cause, this is why I was dubious. Maybe this is going to be a gradual fix, one thing at a time to make sure it's all ok.
If it wasn't in a block in the middle it would be much easier to fit a new roof, I am going to see if they can seal the overlaps inside also as suggested, but I don't want to cause other issues in doing this.
Might also get a second opinion, leaks are a pain!!

Section62

Grenage said:

Phil4432 said:

Get rid of the asbestos, and get a new roof.  This is the safest option for you.

There is nothing unsafe about asbestos cement, as long as you don't cut/sand/grind it.

^Totally untrue.

Any material containing asbestos fibre is potentially unsafe.  You don't have to use power tools or abrasive methods on it for fibres to be released.

Furthermore, asbestos cement roofing is brittle and is dangerous to walk on.  And applying pressure to it from ladders, or walking on it, is likely to cause cracking which causes the potential for further leakage.

Phil4432's advice is spot on.  Either leave the stuff alone, or get someone to replace the roof.  Risking your health and/or safety doing bodge repairs on this kind of roof simply isn't worth it.

Grenage

Putting sealant in gaps from below is not going to disturb the asbestos; undisturbed asbestos fibre cement is not dangerous.

Section62

Grenage said:

Putting sealant in gaps from below is not going to disturb the asbestos; undisturbed asbestos fibre cement is not dangerous.

Asbestos-containing materials are dangerous, full-stop.

By not disturbing undamaged asbestos cement products, it is possible to minimise the risk of exposure to asbestos fibres.  Exposure to asbestos fibres will never be zero in the context of a garage roof as weathering will have damaged the surface of the material and some asbestos fibres will be free. However, the level of risk involved in this situation will be at the low end of the scale.

But that is very different to saying "nothing unsafe about asbestos cement, as long as you don't cut/sand/grind it".

Applying sealant to asbestos (working from below) - depending on its condition - could potentially be done with minimal risk of fibre release if a great deal of care is taken, and so long as the temptation to start brushing it (to remove cobwebs etc) is resisted.  But again, that isn't that same thing as "nothing unsafe about asbestos cement...".  For the layperson it is simply better to leave it alone and seek advice from a suitably qualified professional, and it is unlikely that a suitably qualified professional will recommend repair of a defective absestos cement garage roof vs replacing it with a modern safer material.

Grenage

Small amounts of asbestos fibres are in the air we all breath every day.  I obviously agree with you that it should not be broken up or damaged by someone who doesn't know what they are doing.  We will have to agree to disagree on the dangers.

The pickle here with replacement (which is preferable) is the neighbour's unwillingness to foot the bill to have theirs replaced at the same time.  Of course even then, perhaps rain is getting in because the pitch is insufficient.

I replaced mine recently (also terraced); thankfully my sheets were overlapping theirs.

markin

If the moss is slowing the flow and taking up its capacity then in heavy rain it could simply be flooding over

Ganga

And make sure you wear a mask when doing this to protect yourself from possible asbestos fibres/dust.

20vt-rs

markin said:

If the moss is slowing the flow and taking up its capacity then in heavy rain it could simply be flooding over

Thanks for this, you know I reckon this is likely the cause (or one of them). Had a roofer out to look and they said they are not able to scrape moss off because the roof is asbestos. I think it can simply be lifted, big chunks anyway, but I am not sure if anyone can do it. He did say there are rubber washers / gaskets on the sheets that have perished, and those can be sealed back in, going to get that done at least and see how it goes. Shame he can't remove the moss at the same time!