Damp patches appearing on new plaster

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Evening all.

I recently had the walls on my stairs re-plastered (within the last two months) and a very fine job too.

The walls had been drying out fairly nicely but when I went to paint yesterday I noticed some damp areas on the inside of the external wall. They also have a white substance on them (It makes me think of the crystals you sometimes get on brick but this was smooth).

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This second picture isn't very good but the bits that look white are actually dry plaster colour! However you can see that there are some odd patches on the wall.

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Has anyone got any idea what is happening here? The wall was originally covered with wallpaper which I stripped off in the summer. Some of the plaster was blown, particularly on the inside of this external wall of the house round the front door. The outside of this wall faces south and is rendered but it is a wind tunnel and rain does get blown against it. The render is looking quite badly stained so i'm wondering if water is soaking through?

So I think I actually have two questions:
1) Is plaster looking like this normal or is it a symptom of other issues (perhaps damp on the outside of this external wall)
2) If I do have damp on the outside of the external wall what do I do about the render on it? Would it need replacing?

A few years ago I paid to have it painted with some specialist paint to protect the render and ensure it remained waterproof. When the paint started to discolour I contacted the manufacturer as it was under warranty...only to be told the company that had done the work hadn't used their product...

Any help appreciated. :)
 
Show us the other side of the wall please

All the way up to the roof

Include all gutters, downpipes, overflows, plumbing.
 
Thanks John. You can see from the pics that the gable end isn't looking great. However there is no running water/waste pipe that runs along that side and no overflowing guttering either! I'd also add that the worst bit of the outside of the external wall (to the left hand side of the window) correlates with the dampest patches on the inside of the internal wall :cry:

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There is a lot of water in that wall but I don't see where it's coming from. Is there a bathroom or shower nearby or above? Water tanks or other plumbing? A boiler?

Are those pipes or cables?

Look at the wall during and after heavy rain, see if water is dripping or blowing off the roof.
 
I'd suspect all the rendering has failed.
Maybe the gable pike was rendered first. Starting from & going up from a stop bead(?) in line with the eaves.
Then later the lower rendering was brought up to the stop bead?
Moisture could be creeping behind the render at the stop bead, cold joins are always suss?
All the lower render has to come off back to brick so you may as well remove all render from the gable before making good.

Same inside the house, hack off back to brick.
Up to the gable pike is it a solid wall, the pike might be single brick on snapped headers?
Inside the damp shows going up the plaster to the peak, maybe the verge needs attention as well as the render
 
Thank you for the replies chaps and apologies for taking so long to respond!

I've taken another couple of pics - the first shows the pipe going up the wall. It's appears to be old cable trunking and has got two cables running up outside (can't quite work out what they're doing but it's certainly not anything water based.

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You can see how far the water is coming inside the house with this second pic.

IMG-20240131-WA0004.jpg


So to conclude... it sounds like I need to go back to brick on the whole of this side wall and then get it re-rendered. I've got a carport up to the wall at ground floor level so guess that will need part dismantling (removing from the wall) for a proper job.
 
Thank you for the replies chaps and apologies for taking so long to respond!

I've taken another couple of pics - the first shows the pipe going up the wall. It's appears to be old cable trunking and has got two cables running up outside (can't quite work out what they're doing but it's certainly not anything water based.

View attachment 331456

You can see how far the water is coming inside the house with this second pic.

View attachment 331457

So to conclude... it sounds like I need to go back to brick on the whole of this side wall and then get it re-rendered.
Be aware, you may cop for Building Regulations Part L. Go for a polymer render - steer clear of S/C render.
 
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