Sealing Corrugated Asbestos garage roof

macbery

Hi
Does anyone have any experiene or recommendations for using some of the paint on polyurethance or silicone sealant products for waterproofing a garage shed with corrugated concrete / asbestos sheeting ? Such as Rawlins Dacfill, Cromar Hydrosil, or Mariseal 250 ?

I have an old garage / shed with about 45m2 of corrugated sheet roof which is leaking and the sheets are visibly absorbing water and moist when viewed from inside. I don't want to replace the roof and would prefer to just seal the existing roof sheets to extend the life of the roof.

Any tips or recommendations welcome
thanks

CoBo55

Can you slide felt under it?

The Continental Op

First thing I'd do when its dry is seal it with PVA. That should at least help bind it together and reduce the amount of dust it produces. iirc one part PVA with 5 parts water is what is generally used plus a drop or two of a wetting agent (washing up liquid).

Spray it on with a knapsack sprayer and keep at it until no more is absorbed. You can also use any type of hand sprayer. Do not pressure wash the outside.

Stigura

macbery wrote: »

I don't want to replace the roof and would prefer to just seal the existing roof sheets to extend the life of the roof.

Any particular reason you want to go down this route?

Only reason I ask it that I had just such a roof. It just wasn't happening as I'd stood and watched another like it collapse and fall in. Once they start? They tend to finish. I Needed this roof.

Unfortunately, I can't offer any figures off the top of my head. But, I had the whole lot ripped off. Most of the ~ by now ~ rather dodgy timbers replaced. Opted for some ridiculously more expensive steel sheeting, based purely on colour. Then had a couple of decent concrete slabs poured and a wall built, etc.

As far as I remember? It came in at around two grand. All of it. JCB, Concrete. Team of men. I never lifted a finger

Given your, perceived, situation? I'd be seriously considering the stress and drama of doing anything meaningful to that rotten roof. Vs. the price of just having it ripped and tipped. Whole, gleaming new roof that same day.

Calahonda52

Safe access is the issue here as the roof is beginning to fail. The severe frost last night (2nd/3rd Jan 20201) wont have helped

Stihl waters

The Continental Op wrote: »

First thing I'd do when its dry is seal it with PVA. That should at least help bind it together and reduce the amount of dust it produces. iirc one part PVA with 5 parts water is what is generally used plus a drop or two of a wetting agent (washing up liquid).

Spray it on with a knapsack sprayer and keep at it until no more is absorbed. You can also use any type of hand sprayer. Do not pressure wash the outside.

I might be mistaken but isn't pva an internal sealant and will degrade with external weather conditions, sbr may be more appropriate but if it was me I'd paint it with evercryl, 70 euro a can so it might not be cost effective

The Continental Op

Stihl waters wrote: »

I might be mistaken but isn't pva an internal sealant and will degrade with external weather conditions, sbr may be more appropriate but if it was me I'd paint it with evercryl, 70 euro a can so it might not be cost effective

Its really just to stop the Asbestos degrading further. If water is coming through the Asbestos then so will PVA when its dry.

I don't think PVA is recommended anymore for long term control of Asbestos dust but in the short term it will glue many of the loose fibers together while a longer term solution is sort. You can get an outdoor grade of PVA

Painting the outside is all well and good but I'd be concerned about the Asbestos fibers coming off on the inside.

macbery

Stigura wrote: »

Any particular reason you want to go down this route?

I was looking for a cheap solution without taking the place apart. Once you start with the roof the redecorating list just keeps going. Just disposing of the asbestos sheets properly looks like it would cost several thousand.
Thanks all for the feedback. Guess it's time to get a few quotes to really understand the options ahead.

The Continental Op

macbery wrote: »

I was looking for a cheap solution without taking the place apart. Once you start with the roof the redecorating list just keeps going. Just disposing of the asbestos sheets properly looks like it would cost several thousand.
Thanks all for the feedback. Guess it's time to get a few quotes to really understand the options ahead.

Do you honestly know how dangerous old asbestos sheets can be? They aren't all the same but some can contain the worst forms of asbestos although now I think they are all treated the same way and all considered extremely hazardous.

From your description of the water coming through I would guess that the asbestos has gone porous which means its starting to break down and be in a condition that will release the harmful asbestos fibers into the air for you and others to breath.

As Calahonda52 has indicated this current weather isn't going to help. If the sheets are porous they will have water in them which will freeze and lead to further breakdown.

Sealing the top is a good idea and most of the products you listed will help stop the sheets breaking down further and waterproof the roof but that is only half the problem as you still have the underside of the roof which could continue to degrade and release asbestos partials into the air.