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Asbestos Sofits / Facia boards - How to seal & decorate?

Didn’t they do well in the 50’s…council houses everywhere…very well built and then they go and put asbestos sofits/boards underneath the roof gutters!!!

On this example they are all solid and intact and I’d prefer not to remove or replace. They are also very evenly laid and just suffer from that grey dulling over time. The front facing woodwork is also suprising good and the council fitted some very high quality guttering maybe 15 years back I guess.

So my question is…what to seal the asbestos sheets with? And then what to paint with to get the best finish? The wooden facing boards I’m fine with…Zinseer (or similar) then Spachtel then Sikkens. But the downward facing asbestos I don;'t have a clue how to approach.

Would be grateful as always for some proper expert help to get it right. All the best and many thanks in advance.

PS can post a photo later to show better what I mean

Please please follow the safety precautions in this HSE sheet (PDF)

If you can spray the primer coat, all the better for reducing the dispersal of dust and fibres.

What I know for sure:

Emulsion paint will seal asbestos, but won’t stop any staining present.

In a conventional system, alkali resisting primer sealer will seal asbestos and prevent staining coming through, and deals with saponification. For the topcoat, an oil based or water borne Sikkens finish would be fine.

Keim mineral paints are alkaline as is the asbestos, so you can seal, decorate and avoid saponification with a couple of coats.

(Saponification is a reaction between alkaline salts in the substrate and slightly acidic paint - most modern oil-based paints - creating a soapy scuzz below the surface.)

What needs clarifying: (@BenSturges will know)

Where I am not sure is the long term prognosis of mineral paints holding back water stains present on the bare asbestos surface.

All explained here by Keim (PDF)


Andy many thanks for this…a full explanation as always and as importantly…I learnt a new word…‘saponification’…was worth the ask just for that one :grin:

Will take a read of the H&S guides for sure…more careful about this stuff these days.

Then it is a case of identifying the right primer which hopefully Ben can help with as you mention. Hi Ben.

And I’m guessing I avoid the spachtel treatment on the basis that sanding would be a no-no.

Any other intermediate filler/thick primer Andy that would even out the ripple finish on the Asbestos base? Keen to get it as mirror like as possible.

Or indeed any known method to apply a thin hard surface onto it that might make life easier to paint/finish?

Thinking out loud would it even be a case for a thin uPVC board…shudders in the style of sideshow bob!

Cheers Andy

That wouldn’t be a bad idea really, encapsulating it. When it comes to fixing the covering though without creating dust, that would be a question for a different forum or an installer. We won’t mention the uPVC word to your neighbours if you don’t.


Keim IG Primer to block stains, then the Keim Soldalit/Royalan system will work fine for you on this.

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Happier now…uPvc I wouldn’t be able to live down :slight_smile:

Going to take a look at the products you mention and get back to you. Looks interesting. Many thanks for the pointer. Ok to come back with questions as they might arise? New products for me.