plaster not drying due to damaged render (Ed.)

[jene troy]

Hello,
I had some plastering done last August, there was one section of the room where the previous plaster was crumbling off the walls, so that wall had much more plaster used to full it, so has taken much longer to dry. It is now 7 months later and the plaster still hasn't dried (see first picture), for the last two months we have had a heater next to it and dehumidifier and it has turned a lighter colour and doesn't feel damp, could it be dry and that will just be the colour of the plaster?

Secondly, I have looked on the outside of the plastered wall and I'm unsure if there is water getting in due to the wall being damaged. I have attached pictures below, are the blocks on the wall a type of cladding, or waterproofing? Can it be repaired and would that solve the issue? A builder suggested digging out the cracks and using exterior filler and using a thermal plasterboard for the internal wall and reskimming.

Thank you in advance for your advise that you can give.

 

[jj4091]

What did he use as a base coat to reinstate the inside walls, sand and cement then skimmed over, or browning skimmed.
The blocks on the wall are a pattern scratched into sand and cement render if you want a proper long term fix then it needs to be all knocked off and redone any thing else is just a temporary bodge as far as I am concerned. That could well be the reason for your penetrating damp but there could be other reasons such as brick ties being bridged with mortar along with the render problem. I am making the assumption that you have cavity walls. If they are solid then the render definitely needs replacing.

 

[jene troy]

Thank you for your response, as far as I'm aware the plasterer used plasterboard followed by a much thicker layer of plasterer in that area due to the previous plaster crumbling on that wall.
I don't have cavity walls as it's a victorian property.

 

[Lower]

Judging by the dirt on the outside wall, you've got water running off the edge of the roof and down the wall which is penetrating through the render.

 

[ree]

jene troy,
1. Your solid walls have been penetrated by damp - what you see on the inside is damp penetration.
2. all the plaster etc must be hacked off back to brickwork and then rendered with sand & NH lime in 3:1 mix. And skim finished with a custom remedial finish. Plasterboard must not be used
3. Investigate inside the built-in closet for perhaps more damp or condensation.
4. The outside render to the whole back elevation has failed - damage can also be seen on the side wall render. It must be hacked off to brickwork and rendered with a 3:1 S&L mix.
5. The "blockwork" lines are merely decorative render - its called Ashlar or pretend stone blocks.
6. The verge above your rear wall is wrong - its allowing water to drip down the render. The verge needs correcting with an undercloak and pointing.

7. FWIW: the flashing above the shed extension and the side wall bay is wrong, and needs re-doing.
The chimney stack might need attention?
The extn parapet is covered with felt - felt used as flashing usually fails.

 

[jj4091]

A word of advice don't use the same plasterer again as he should have advised you of all the problems that need rectifying unless you told him just to do as he did. Frankly what he has done has been a waste of money.

 

[jene troy]

Thank you for all of your responses and advice.
If the cause of the penetrating damp is fixed (externally), will this not allow the plaster to dry, instead of hacking off all of the plaster?
Why should plasterboard never be used? Is that due to having solid walls? Or does it always have the potential to allow damp in?

 

[JohnD]

If the cause of the penetrating damp is fixed (externally), will this not allow the plaster to dry, instead of hacking off all of the plaster?

It might do. Fixing the source of water is certainly the first thing you should do, because it will stop things getting worse, and allow the house to start drying.

 

[JohnD]

6. The verge above your rear wall is wrong - its allowing water to drip down the render. The verge needs correcting with an undercloak and pointing.

7. FWIW: the flashing above the shed extension and the side wall bay is wrong, and needs re-doing.
The chimney stack might need attention?
The extn parapet is covered with felt - felt used as flashing usually fails.

Ask around for an experienced local roofer with a good reputation.

Note that websites where people pay to be listed are not recommendation sites, they are advertising sites. Even if they have misleading titles to trick you into thinking they check the workmanship of advertisers and verify that they should be rated. Be aware that reviews might be written by their mum.

Keep an eye out for houses having work done, make a note of the address and the name and number of the firm. After they have finished, have another look and try to speak to the householder. If you can take photos without causing offence, they might show quality of work. Roofs are very visible.

Do not use anyone with no address and just a mobile phone, or any itinerant who knocks on your door.

 

[ree]

OP,
The external render must come off.
The interior has to be dealt with as my above post - no easy way out.
If you attempt to save a few quid by leaving any damaged plaster on the wall it will come back to haunt & cost you - more money, more disturbance.
I've advised renewing with S&L render specifically to give the wall a chance to breathe - plasterboard would eventually end up stained and decaying.