Wet wall and plastering

Question

A builder repaired a wall affected by a leak. I explained that it needed to be completely dry before replastering, but he applied PVA, plastered and skimmed it anyway.

He says the wall was dry, but it still feels noticeably cold, so I’m concerned there may be remaining moisture. The plaster is also uneven and overlaps the skirting board; he says sanding will fix this.

Please advise:

1. Should the wall be checked with a damp meter before further work or painting?
2. Could remaining moisture show through the paint?
3. Could applying PVA and plastering too soon trap moisture?
4. If the wall is still damp, should the plaster be removed and the wall allowed to dry before replastering?
5. Will sanding properly correct the uneven finish?

I want to resolve the moisture issue properly before decorating\.

Mark · Accepted Answer

Idealy the damp in the wall would be dry but pva is not water proof in its self acting as a bonding agent for the plaster which is wet anyway over time will dry place a fan to speed up not heat quality of the finish is down to the plasterer masking tape and a wipe dwn would have protected skirting

Corey · Answer

I would personally recommend getting it tested with a damp meter and looking out for any signs of damp still, such as the plaster not drying the same colour in places. If moisture is found in the walls i would say hire a dehumidifier to draw out any more moisture from the walls and inspect the plaster periodically through the course or a week or so. If the levels of moisture do not drop then yes the plaster will have to be removed and a continued period of drying is required. For the uneven finish sanding will only get you so far depending on how bad the finish is, i would say get some filler for example easifill and fill in any bumps/low points on the wall once dry sand again
Hope this helps 
Many thanks 
Cp home improvements

Irina · Answer

Yes, I would have the wall checked for moisture before any further decorating.

If the wall was affected by a leak, it needs to be genuinely dry before it is sealed with PVA, replastered and painted. A wall can feel cold without necessarily being damp, so temperature alone isn’t a reliable indication. A suitable moisture meter can give a much better indication, ideally with readings compared against an unaffected area of the same wall.

Remaining moisture can cause problems after painting, including staining, discolouration, blistering, peeling or poor adhesion. Applying PVA and plastering before the wall has properly dried can also slow the drying process by reducing the wall’s ability to release moisture.

If there is evidence that moisture is still present, I would not simply paint over it. The appropriate remedy depends on how wet it is and how well the new plaster is bonded, but in some cases the affected plaster will need to be removed so the wall can dry properly before being replastered.

As for the finish, sanding can deal with minor surface imperfections, but it won’t properly correct significant unevenness, ridges, hollows or plaster that has been taken over the skirting. Those issues may require additional preparation or remedial plastering rather than simply sanding.

I’d therefore resolve the moisture question first, then assess the plaster finish once you’re satisfied the wall is dry. I wouldn’t let the wall be painted until those two issues have been checked.

Paul · Answer

Get a demidefire and pull the moisture out slowly then paint and it shouldn’t need sanding that’s bad on the plasterers behave a good job wouldent need it

Mark · Answer

No plasterer should have any plaster on skirting board , that’s unprofessional,, you will not get finish plaster to a smooth finish if walls are damp , the finish will be lumpy,  Little raised pimples . More worried for you that levels are all wrong , skirting may need to be removed to achieve level wall .? Hope that helps . Call for any advice 
Pride plastering 
Mark

Tj · Answer

1 - yes moisture needs to be checked to prevent further issues, such as mold growing to answer question 2. 
3 - yes. 
4 it is possible to dry any moisture without removing the plaster, however depending on how bad the finish is (continuing number 5 also) it may be more efficient to remove the old plaster and air completely before re-skimming.

From what I have read it would be best to assess to area in person to determine whether removal is needed.

Simon · Answer

It should be knocked back to brick ,treated, bonded and a new plaster finish

Raul · Answer

Ideally have a dehumidifier dry the wall and if there is no continuous moisture like damp affecting the wall it should dry and you should be ok to paint it.Sanding it will correct the uneven finish.

Luke · Answer

Yes I would check the wall for damp again 
If there is damp in the wall still it will appear through eventually again if it has dried out properly 
Yes pva and plaster could trap damp in and it will appear through again 
Yes the plaster should be removed and it needs drying out properly and accessed for further works it could possibly need tanking first before plaster
Plaster shouldn’t need sanding if it’s done correct but it can help certain areas if it’s uneven and not really bad

Wet wall and plastering

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