SBR help

[Jarveye]

I am a novice when it comes to renders/exterior masonry work but I’m forced to fix things myself on this occasion! So any help appreciated

It’s an old stone building with what I think is originally a lime/pebble render, with many layers of paint (both water based and oil)

I’ve had to dig out and repair some cracks in the gable wall, over the skews and round the chimneys, using a mucture if cement and silicone type sealant (OB1)

I’m hoping I’ve done a good job, I’ve been pressure washing the surface too to remove moss and there had been blistering paint full of water so I’m trying to get all that loose paint off too, but might be hard to get it all off. Then I plan to chloris tge walls to remove and mould spores.

Was originally just going to repaint it at this stage, but someone suggested SBR slurry…

They says you can mix a paint on mixture of SBR, cement and something to make it flexible which will seal/waterproof, bridge and smaller cracks I miss, and give a good new surface for the new paint…

Can anyone confirm or advise on this? Abd give me more details on the mix and application?

Cheers

 

[Jarveye]

Anyone got any advice here? Desperate for help

 

[lostinthelight]

Your doing as so many others do by trying to seal walls that are built to breath.
Stone walls expand and contract hugely throughout the seasons so not sure if Sbr would be flexible enough not to crack. Water gets behind any coating through hairline cracks that may not be visible until the wall is wet, this runs down forcing water filled bubbles to appear .
I doubt you want to take the traditional route so would look at a highly flexible paint like High Build or even stretchier Bedec which I painted on an inner tube, let it dry then inflated it and in didnt crack

Bedec Extra Flex Elastomeric Masonry Paint

Microporous Masonry Paint with up to 400% elasticity for use over cracks. For roughcast, pebble-dash, brickwork, cement and concrete rendered surfaces.

www.promain.co.uk

 

[Jarveye]

Thank you, can I ask, how do those masonry paints compare to oil based masonry brands I’ve been advised to use like tikkurila valtti or even dulux/sandtex

I especially concerned about durability as we live in Shetland which is extremely exposed and the life of outdoor masonry paints tend to be much less here

 

[tell80]

Is the render on the cottage firmly fixed to its background - or considering the problems you've mentioned is it worthwhile hacking it all off back to masonry and starting again with traditional render or one of the new renders?
As for painting render esp in exposed positions its a fraught subject as to whats the best method or material to use. Local knowledge would be your best bet.