How soon can you paint a rendered wall?

JustAnotherSaver

The mix will include lime or 'strengthening fibres' i know that much, and rendering/plastering sand (not grit/sharp sand and not building sand).


Basically the recess where our multi fuel stove is is going to have the boards cut out and rather than be boarded out (because it hasn't worked) it's going to be rendered.


I know the stove is to be removed one day, the plasterer is to come in the next and render up and then a day or two later the stove guy will come back to refit the stove.


What i'd like to be able to do is get the render painted up before the stove is refitted as it'll just be so much easier to access, especially at the rear. Just wondered how soon you can do it?

Grey_Critic

Talk to the guy who is doing the rendering he will be able to advise you - it is his job.

Davesnave

I'd say it depends very much on what sort of final paint finish you want to use. You wouldn't paint a normal plaster wall so soon after plastering, and then you'd first use a mist coat of non-vinyl, breathable paint, 10% thinned.


While this isn't plaster, you want it to dry out evenly and thoroughly before painting, and especially before lighting up a stove next to it.
I'd think much longer than 2 days is required

stuart45

If it's lime render, it hardens by absorbing CO2, so you need to allow it longer than with an OPC render, otherwise it may dry out before it cures properly.

JustAnotherSaver

That's the reason we're getting this done halfway through next year - once the 'burning season' is over and radiators are no longer getting used - so that it can dry out naturally.



Though as our walls have been tanked under the existing board i contacted Sovereign to see whether it could be rendered on top and they stated:

A sand/cement render can be applied to K11 tanking system, it must be bonded to the tanking as follows:

Before rendering apply a Bonding Coat consisting of SBR Bonding Agent:water 1:1, mixed with fresh Portland Cement. Achieve a thin yoghurt consistency and brush thinly over the walls. Render up while this is still tacky. If the Bonding Coat starts to dry then re-apply.

However we cannot make recommendation to thickness of the rendercoat required to protect the tanking system from the excessive heat.