Help please - is this damp or something else??

[alexisj]

Dear all,

We had an attic conversion two years ago and about 9months ago, the paint on the external wall on the side of the staircase started to peel off.

Called in the builder who did this and he said it's because they forgot to put base layer of paint in.

However the peel keeps expanding and now I can see all the salt like white powder substance appearing on the wall and the plaster also cracked.

I haven't seen mould on the wall until I took down the paintings on the wall and the back of the paintings are covered in green mould.

Now I also see some small bubbling on the more distant side of this wall.

I attach pictures for above.

Have anyone got experience with this before that can advise us what this really is? Would appreciate any sharing and comment. Tbh I lost faith in our builder and don't want to trust him any more.

Many thanks!
Alex

Reattaching pictures here

How long was the plastering left to cure and dry before painting ?

What's on the other side of that wall?

I'm not sure unfortunately. I thought it is until it's all dry and pink and but I don't know.

Nothing but outside air? But there is a black pipe running alongside that wall horizontally outside.

My dad always told me fresh plaster shouldn't be painted for 4 weeks.

The new bubbling on the same wall but to the far left...

@pigletjohn any advice?

So it's an external wall? How old is the house and is it an original wall? Is it rendered? Are your guttering, downpipes and drains working?

In some of the pics it looks like efflorescence where moisture & salt deposits leach out of the plaster. Usually because it hasn’t been left to dry for long enough.

Yes it is external.

House is 1920s, but this wall is brand new as part of the loft conversion we did two year ago.

On whether guttering or downpipes are working - I don't know whether they are but nothing seems to be causing problems yet?

It might just be residual moisture making its way out, so make sure to ventilate well and keep things and pictures away from the wall.

I think it's probably damp. Please show us photos of the outside wall. It might be a gutter or downpipe. Could possibly be roof or plumbing. Have a look in the loft for signs of rain leaks.

If you scrape off the loose paint and efflorescence water can evaporate out. See if the powder fizzes when you drop it in vinegar.

There's a faint chance the brickwork was soaked with rain during build, but it should have dried after a year.

If you tape a piece of clingfilm tightly to the wall, you can see if water appears behind it (as it can't evaporate) from a wet wall.

In the event that water forms on top of the clingfilm (the room side) then it is condensation, e.g. from a steamy shower, but I think that is unlikely.

Please photograph the entire wall, ceiling to floor, to show the pattern of the damp patches.

P.S.

If you want to hang a picture or mirror on the wall, put corks on the back to space it off the wall and allow air circulation.

P.p.s.

In you first pic I can see a patch of brown plaster showing through. This is wet. If you scrape off the loose paint the pattern of damp may be easier to see. The source will be behind and above the damp.

When you have found and repaired the cause, you can use a porous paint to make the wall look decent while it dries out. Dulux Trade Supermatt is a non-vinyl emulsion made for this purpose. It is not washable or durable but can be recoated with your choice of paint once the wall is fully dry. Colour choice is small off the shelf but a Dulux centre can mix it to order at extra cost.

Some other companies also offer a non-vinyl, usually badged "for new plaster"

I'm not a specialist like PigletJohn, but I was going to ask if you could let us have a photo of what's immediately the other side of the area affected and also one taken of what's above - appreciate you won't be able to get too close, but might help.

Picture 1 shows the pattern of the bubbling, with the end bit circled in red;

Picture 2 and 3 are outside the wall but I can't get the top view;

Picture 4 shows the plaster close to the end bulging out

Just did the vinegar test - no the powder does not fizzle. Very lightweighted.

It looks like water ingress either from a dodgy joint/flashing in the roof, or from the outside wall itself. It's difficult to see on the photos, but the white wall on the outside may be looking a bit patchy.

Crikey, that's not great. Water is coming in from somewhere. Do you have a guarantee on the building work?

I should also mention there is a bath/shower behind the adjacent wall to the right of this wall in the picture

Does the grouting/sealant around the bath/tiles look intact, ie no gaps? Could be worth having a look under the bath to see if floorboards look a bit damp/stained.

The picture with the red squiggle appears to show a horizontal crack, with a mass of damp at about the same level.

On an outdoor picture, please indicate the part of wall that corresponds to this position.

Is the wall a cavity wall, or built with solid blocks?

What is the black pipe?

Relative to the crack, where are the shower head, pipes and top of bath?

Now we have the important information that the shower backs onto that wall, the mostlikely is a breakdown of grout or sealant, or cracked tile.

I think you have a leak ! Tbh
water ingress is difficult because it travels
along the brick work etc( meantime get roof flashing fillets etc checked ,for breaching and anything gutter wise above the damp .
get a different builder to look ( recommend by a someone)
meantime scrap all loose paint off don’t over paint it atm
but bleach and damp cloth were there’s mould
(wear a mask) when doing
👍👍