DOFF machine is ruining render - best course of action please?

blizeH

Hi, we had a problem whereby the render wasn’t sealed before being painted, and it was bubbling/flaking all over - we tried painting over the top of the ‘good’ stuff and even that flaked off very easily

We opted for a package from a company that use a DOFF machine to remove the paint, but it’s left the render looking like this. They’ve only done the one wall so far but it looks pretty terrible. Before it was just pretty smooth.

It’s through a building company and I’m not sure whether to persist with them and give them a chance to fix it (currently have paid £2k for the scaffold to go up of a £11k total, including garage) or whether to just bite the bullet and pay £30k for new coloured (and insulated) render, or pay a painter I liked £6k to just scrape the rest of the walls and paint it

Thank you 

blizeH

They’re claiming it definitely wasn’t the DOFF machine and the render must have been like that underneath the paint

stuart45

Did you have it rendered?

ThisIsWeird

blizeH said:

They’re claiming it definitely wasn’t the DOFF machine and the render must have been like that underneath the paint

I'd have thought that this would be easy to evidence. Did you have any 'before' pics of the finish? Or do the removed paint flakes have thin layers of render attached to them? (Or is it a mulch?!)
That's an awful finish, and the previously painted finish would have looked equally awful.
Does that surface feel soft? What happens if you scrape it - run a nail along it?
If it's adequately hard, then I guess the cheapest solution would be to first 'stabilise' it with stabiliser, and then roll on a high-build paint to give it an even finish. But you'd need to want the resulting texture, and I've had no experience of these products. They look thick, trowelable on, so check out what finishes can be achieved.

blizeH

stuart45 said:

Did you have it rendered?

Nope, it was rendered around 9 years ago but painted on without a stabiliser causing lots of bubbling and flaking

ThisIsWeird said:

I'd have thought that this would be easy to evidence. Did you have any 'before' pics of the finish? Or do the removed paint flakes have thin layers of render attached to them? (Or is it a mulch?!)
That's an awful finish, and the previously painted finish would have looked equally awful.
Does that surface feel soft? What happens if you scrape it - run a nail along it?
If it's adequately hard, then I guess the cheapest solution would be to first 'stabilise' it with stabiliser, and then roll on a high-build paint to give it an even finish. But you'd need to want the resulting texture, and I've had no experience of these products. They look thick, trowelable on, so check out what finishes can be achieved.

Thanks! We do have photos from before, but nothing close up that documents it too well I spoke with a decorator earlier who said it's likely that it needs to be re-rendered, what a nightmare! The surface is quite soft unfortunately. I haven't checked since it's still wet, but before it was quite chalky in places

ThisIsWeird

To re-render will likely mean all the existing taken off first. Getting to be a major job.
Was this decorator an experienced fellow? Could they speculate on whether stabiliser and textured paint might do the job?
Your render hasn't 'blown' anywhere, so is presumably still well attached. The only issue being that it ain't as hard as it could be (silly Q - it isn't lime-based, is it? How old is the house, and are the walls solid or cavity?)
I have no experience of these thick textured paints, but just became aware of them recently. Does your decorator know about them, ideally used them?

FreeBear

ThisIsWeird said:

To re-render will likely mean all the existing taken off first. Getting to be a major job.

When I stripped my render, the top layer was pretty soft - Much of it came off with a wire brush and a diamond cup wheel on the end of an angle grinder. Underneath was a very hard layer of cement based render.

It is possible that the OP has a soft top coat over a hard base coat. Being done ~9 years ago, it is unlikely to be a pure lime render.

stuart45

The top coat on cement render is normally weaker than the scratch coat. So if you use a 4/1/1 for the scratch it's 5/1/1 for the top coat, and if the scratch is 5/1/1 then it's 6/1/1 for the top.