Render or paint issue

[caladrisalpina]

This is a south facing wall, thermolite block rendered. We’ve been in the property 15 years, I believe this extension was done late 90 ‘s. It has been painted with Sandtex masonry paint on several occasions, but regardless of whether it is painted with the bubbled/ flaky paint scraped off with the good areas left , it still bubbles up and flakes off. Given other truly awful workmanship in other parts of the extension, I don’t know whether it needs re-rendering or the wall treating prior to re painting. It’s a lounge wall if that makes a difference (not kitchen with potential associated damp issues) Thanks in advance

 

[opps]

The cracks in the render may be allowing water to get behind the paint.

Some of the cracks have previously been filled.

You could rake out the cracks and fill with Toupret Fill and Flex.

Toupret Fill-Flex Ready-To-Use Flexible Filler White 310ml - Screwfix

Order online at Screwfix.com. Suitable for both internal and external use. Highly flexible filler for gaps and cracks, ideal for skirting and architraves where movement is possible. Moves with the substrate with no cracking, and adheres to paintwork with no need to spot prime. Can be used on...

www.screwfix.com

It is like a decorator's caulk with reinforcing fibres.

Like caulk, it will shrink back after a day or two. Then fill with Toupret Touprelith F.

Toupret Touprelith F Exterior Masonry Repair Filler

Fills without depth limit and repairs without formwork. It will adhere to damp masonry and is weather resistant while also being easy to shape. Usable on all rough masonry surfaces, and can overcoat 48-72 hours from application.

www.toolstation.com

It is easy to sand back.

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