Plastering & Rendering

Damp and plastering options

Anonymous user 28/02/2024 - 3.53 PM

Hello all, Desperately in need of some advice please (would also put my mind at ease too). Currently in the process of re-plastering my front room and after removing all of the old plaster, unfortunately we have found a few areas of damp. One is on the chimney face (which we may remove) and we’ve found the cause of that being a slight leak in the chimney pot/cap. Another is to the left of the chimney, heading towards the front of the house. This rises up to about 30-40cm and covers a width of about 2-3ft. Its exactly where a bookcase had been pushed right up against the wall, it had been sat there for about 10 years! So I’m wondering if this damp area is due to the wall not being able to breathe effectively. All other walls seem to be fine, apart from the two small areas where patches of moisture are visible on the brick and in the mortar, rising to about 15cm max (skirting height), about a foot or so wide. I’m waiting for a visit from a builder on identifying the cause some of the damp areas. But in the meantime, I would be very grateful to receive some advice on the finishing process for the walls please. Waiting for the moisture to dry out will take a LONG time so my initial thoughts are: 1) Stud/Batten walls > Board > Skim. But I'm unsure on which type of board to use. Do I go for a vapour/foil backed board or moisture resistant (green) board? This also brings the issue of applying insulation in the gaps between board and brick. Does the insulation material have to be applied from top to bottom? And can I just use any type of board/insulation roll or should I avoid certain types due to the moisture problems? As for the battens, I'm thinking treated timber or roofing battens. I was advised to apply foil tape on the face of the battens which meet the plasterboard, especially up to a metre from the floor up. Is that really required? :S 2) Insulated plasterboard applied with adhesive. My only worry here is moisture coming through the dabs of adhesive leading to patches of damp on the plaster. I heard elsewhere that condensation could collect on plaster where dabs have been applied. Not entirely sure if this is true though? I guess it’d help if I add some detail about the property :) It’s a terraced house, not exactly sure on the age but I’ve been advised it may have been built 1920 onwards. Solid red brick walls with no cavity. I look forward to any advice. Many thanks :D

Anonymous user

Don't bother asking anybody on MyBuilder cos most of them don't know what the deal with

Answered25 June 2021

Like

5

---

TMW Plasterers.

No reviews yet

Manchester

1st of all, yes the bookshelf could've kept back or trapped the damp there. Here goes... Personally, I would definitely knock the walls back upto a height if 1m minimum. Use a dehumidifier to really dry the walls out. Buy a decent one from Screw fix for around £150. You'll be able to see how damp these walls are. When you ask your plasterer or damp specialist to do the job insist on a great product called Dry-Coat or Renovating Plaster. It's expensive but it's the product used on 'listed buildings' The product can be difficult to rule off and only experienced plasterers can use it. (some of those guys don't like using it) so a very strong mix of Sand and Cement with plenty of waterproofer would do the trick. Make sure when either method is used it has been rubbed up with a proper float to provide mechanical key. As for the thermal.... OK so once these methods are done, either skim the walls or for the thermal value use the G-Tec boards from Buildbase. Use Blue-Grit or True-Grit to provide a superb chemical key for sticking the boards. These boards come at 25mm, 38mm and 60mm I'd use 38mm, they are expensive but super warm and also foil backed to so keeps out vapour. Make sure the plasterer is applying a ribbon of Drywall around the entire perimeter or the board and then apply more through the middle of the perimeter it has to be done right because the perimeter dabs will provide air tight seal to the wall resulting in no drafts. A good rule of thumb is.... If you want a properly fixed thermal board then buy 1 bag of adhesive per 1 thermal 8x4. So if you need 3x boards buy 3x dry wall adhesive. Obviously this is over kill but I've used this method to great effect and even in my kids room. It's the warmest in the house with the 38mm applied to external walls and screwed to the ceiling! Oh, 1 more thing. If the room is on a solid floor aka concrete then leave the boards 1 inch of the floor. If it's on a wooden floor aka floor boards in my kids room... Then I stand the board on the floorboard with no gap (not a text book method but great a sealing things) hope it helps.

Answered28 September 2020

Like

0

---

a.rodi

Rating: 5 out of 5

5/534 reviews

Leeds

Hi,speak to a damp specialist first.you may need damproof course injecting.also they will look at other problems outside property that are causing damp.if they cure the source of damp you won’t have to start fixing frames,boards.limelight renovate 1 metre high an skimmed,if damp as been treated.

Answered12 March 2022

Like

0

---