Repairing blown plaster

[Natedog]

Hello
I was hoping someone could help me with this. This area of plaster has blown, and I was wondering how best to go about repairing it. The whole area is an external wall in a porch and looks like it’s made or plaster tiles / render. I haven’t pulled any of it away yet. Thank you.

 

[conny]

I'm not a builder, and certainly not a brickie or plasterer, but to me that looks like a very thin layer of artex or maybe even just paint.
Looking at the break lines they seem to follow the joint patterns.
They look like 'breeze' blocks behind. Try scraping the peeling bits away and see whats underneath. You may find it is just a block inner leaf. Is the outside faced with brick?

 

[Natedog]

Thanks so much @conny
The outside wall is a brick external wall.

 

[tell80]

Your plaster appears to have blown and cracks can be seen.
I would suspect damp, possibly penetrating damp.
The wonderful floor tiles are Victorian so it maybe an older property?
Whatever, the short answer is it would be best knocking off all the wall coverings back to brick and re-doing the area with a 3:1 render mix of sand and lime - stop the render 50mm from FFL.

Pics showing the outside of the walls at ground level and a pic of the whole porch would help?

 

[Natedog]

Thank you for replying. Some more photos attached.

 

[Pat ex]

I assume this is an unheated area?
In which case your 'damp' may well be caused by condensation on the walls soaking into the plaster. Gypsum plaster is highly hygroscopic.

In which case tell80's solution should solve your problem. lime render is hygroscopic like gypsum plaster, but the damp does not degrade it, and the lime render releases the damp, or 'breathes', when the conditions allow.

After the lime render, redecorate with a breathable 'paint'. Or you could dye the lime render.

 

[Odds]

Thank you for replying. Some more photos attached.

Does the affected area feel damp to the touch?
It looks to be dry from the photo but a couple o' coats of anti-damp paint may do the trick. Just scrape off the flaky plaster first.
Whatever you do keep those fantastic tiles looking as good as that.

 

[Natedog]

It doesn’t feel damp. Should I pull away those old plaster tiles first? And if so what would I replace with?

 

[Odds]

It doesn’t feel damp. Should I pull away those old plaster tiles first? And if so what would I replace with?

If it doesn't feel damp then you may get away with removing the flaking plaster and skimming a fresh coat across the surface, then repainting - i don't see any tiles to remove from the wall, just blocks.

 

[Natedog]

Yes sorry, by tiles I meant the plasterboard type blocks that are coming away from the wall. Would I somehow have to reattach them to the wall first?

 

[Natedog]

I’m not sure if it’s clear from the first photo, but where it’s cracked the board it’s protruding from the wall.

 

[foxhole]

It’s a rendered porch, no plaster .

 

[tell80]

As in my post #4 you have to go back to bare brick.
For penetrating damp the porch has solid walls and the pointing needs raking out to a depth of 20mm-25mm, and repointing with the render mix.
Perhaps you also have rising damp. Is the outside ground level lower than the tiled floor?

 

[Natedog]

Yes it is @tell80 Am thinking it might be too big a job for me to take on. I want to try doing more things myself, but worried about making the situation worse

 

[Alastairreid]

It's cement render not tiles or plaster, remove the loose stuff back to brick and get rid of the gloss paint., patch the blown render and paint with sandtext or suchlike..looks more like condensation to me.