Corrugated Asbestos Roof Crack Repair

[Steve1309]

Hi, Would like some advice on how best to seal up this crack in a corrugated asbestod roof which is letting in water to the area behind. The surface is a stable paint finish. TIA

[Mr Punter]

CT1 is a favourite on this site.

[Beau]

Not tried it on asbestos but Denso tape worked brilliant on some corrugated sheets that had rust holes

Edited 20 hours ago by Beau

[markc]

Denso tape does work well on Asbestos cement sheets, brush away loose crud and rub it down well to get hold.

[JohnMo]

2 hours ago, markc said:

Denso tape does work well on Asbestos cement sheets, brush away loose crud and rub it down well to get hold.

But wear mask gloves etc to protect yourself - if it is indeed asbestos.

[Roger440]

10 hours ago, Mr Punter said:

CT1 is a favourite on this site.

 

Indeed, but on this id want to put some kiln dried sand or similar on it too whilst sticky to prevent UV degradation. (whatever the manufacturers say about it)

[Nickfromwales]

9 hours ago, Roger440 said:

 

Indeed, but on this id want to put some kiln dried sand or similar on it too whilst sticky to prevent UV degradation. (whatever the manufacturers say about it)

Maybe CT1 and then overpaint?

 

CT1 is ridiculously good for this type of thing btw. Not slightly good, ridiculously good, and will stick when wet and stop rain as it’s coming through. Nuts stuff that I used to use to seal up showers and baths etc in student digs where silicone was a constant source of severe leaks and property damage.

 

For this application I would inject it into the crack as much as possible, and then apply it liberally around the affected area, and then work it around with a 2” brush, giving 2-3” of coverage either side of the crack. Same both sides if possible.

 

Jet-wash it if you can, and leave to dry, to remove any friable materiel, and wash away any residue well to get rid of the nasties.

[saveasteading]

All good advice.

It's probably not asbestos fibres but assume it is, so don't brush it.

 

I'd combine the treatments. In dry conditions,  coat the area with a bonding agent to kill dust. Then inject/trowel in CT1.

But these panels can move quite a lot so then stick tape over it. Denso tape is primitive yet effective... but I've no idea how long it will last in sun. 

Tyvek tape may be worth a try... it is very sticky ( by brand, not a 'similar' make).

 

That seems to be along the crown (ridge) so that is lucky. If you can obtain a section of the same profile you could overplate it. Steel, zinc, lead, or a piece of rooflight, and stick it on. 

[sgt_woulds]

I used to do asbestos roof repairs on commercial buildings back in my abseiling days.

 

We used to use Belzona water based rubber roofing paint with nylon reinforcing mesh.  This was applied to the whole roof to strengthen and seal the asbestos sheets completely, inside and out and though expensive it was much more economical than reroofing a massive industrial roof.  Well over the top for a domestic garage roof!

 

CT1 is a fantastic problem solver for small patch repairs like this, and is my go-to for most repairs around the house.

 

For asbestos I would jet wash the roof to remove organic material and let it dry before sealing.  CT1 will go down in the wet, but works better on dry, and it gives you a chance to see if all of the moss was removed.  Use copious amounts of spit - NOT WATER - to smooth it into cracks and the surrounding surface.  It's disgusting, but its the only way to stop your fingers sticking to the CT1!  Unlike NfW, I wouldn't put a brush anywhere near CT1 until it dries, but I would apply some rubber roofing paint or DPM paint for belt n' braces afterwards. 

 

Only jetwash the bit you need to repair, otherwise you can cause more problems than you started with!  However, if the roof is small I'd want to wash, repair, and encapsulate (paint) it all to prevent future issues.

 

Wear a face mask when jet washing (for zoonotic protection more than particulate).  Commercially, the runnoff should be removed, filtered and disposed of as hazardous waste.  What you do is up to you, but make sure it it doesn't just run off onto a surface where future heatwaves might make it friable and mean you or your children might end up breathing it, as miniscule as that risk is.

[saveasteading]

9 minutes ago, sgt_woulds said:

back in my abseiling days.

I'm facinated.

You abseiled down the slope? And if you fell through?

[markc]

14 minutes ago, saveasteading said:

I'm facinated.

You abseiled down the slope? And if you fell through?

Mid 80’s we walked around on single skin asbestos agri buildings - only fell through once when I stupidly jumped over a crack … straight through and bounced off an overhead crane on the way down!

[sgt_woulds]

Not exactly.  We used a fall resist system, not fall arrest (drops).  Think of it as a temporary mansafe system using ropes and movable frames. 

 

I also used to do building repairs whilst 'hanging' which was fun.  I was dangling 80 feet up when the planes started crashing into the World Trade Centre - we'd noticed lot's of military aircraft activity (formations of RAF AWACS!) but didn't find out what the fuss was about antil we got off the ropes.  The week before I'd been on the HSBC tower, which later gave me pause...

 

I did fall through a roof once, but that was caused by scaffolders moving our markers and walkways around the skylight panels (white painted corrugated plastic on our white primed asbestos roof)  The barstools needed a scaffold boards to finish their tower, and unscrewed and knicked the ones we had carefully laid around one of the openings and before the ropeway lock-on point.  Fortunately this was over one of the mezanine offices, and I landed on a photocopier, rolled off onto a table next to a number of paper spikes, and landed in the lap of a very excitable secretary.  

 

The next week I was working in a paper mill in Kent, with our ropes looped over steam pipes that were supposedly shut off for the duration.  Some absolute winker cut the safety locks of the stops and restarted the steam plant.  Half an hour later our ropes snapped, and gravity stepped in. 

 

I was lucky and landed on my heels on a set of access steps 40 feet below; the way I fell meant I only severely bruised my rips and compacted some vertibrae - with just a short period to think about life whilst the nurses gave me bed baths.  The chap I was abseiling with was not so lucky, but is now able to walk again.

Edited 35 minutes ago by sgt_woulds
Fortunately, not unfortunately! the difference was a three storey drop