Type of plaster in 1920s house

Hi would see if the Walls needed to be injected damp proof due to condensation and black ash then I would used sand and cement mix SPR tow coats

if the walls have a cavity I recommend no injection damp proofing, more problem than it's worth and will actually cause more damp. the proper way is to remove some pointing and replace dpm, however that's not your question it was a reply to an answer previously given to you, don't use cement based screeds on old brickwork which will further erode the brick, use lime basecoat and then gypsum multifinish.

Hi, There are a few ways to replaster your 1920s house but first thing to do is make sure the walls are nice and dry and cleaned of dust and loose material and any damp issues are dealt with like if theres rising damp or penetrative damp first before commencement of replastering the walls . The two methods i would use is either using a material called Limelight and its finish or limeplaster as these would allow the walls to breathe and flex as sand and cement is to strong and lacks flexability and in an old house they often move slightly in places and sand and cement is too strong and can crack . Limelight comes in bags and can be mixed with water as so the finish too as lime plaster is usually used on listed buildings . In my experience doing renovations on old buildings and council house's i have always preferred Limelight and gives a good breathable finish to replaster . I am an old school plasterer and tend to use proven products and then stick to them but i should imagine there are probably some new products available nowadays so research is paramount ok . And finally make sure you install plenty of ventilation like vents where you can to help stop any chance of damp moisture returning . Regards Mark Mjplastering

Lathen Plaster is what you have. yes It can be replaces with Modern British Gypsum Plaster, but you must take of all Laths behind the wall. Re-Plasterboard using 12.5mm Plasterboard & then Use the British Gypsum bagged product to skim ontop. This will convert your old lathen walls into a modern method. If you want to keep it traditional & expensive use Sand & Cement

Best option is to remove all laths and board with 12.5mm plasterboard, with you house being 1920 it you should be fine to do this.

After the war, they would make blocks with slag, sand and cement due to cost and availability of materials. If it's a solid wall there's a chance it could be that. If it's lathe and plaster you have two main options (if you have condensation damp you should consider using new lathe and lime plaster to suit the style and age of the building as lime will allow it too breathe, this would especially apply if it's a listed building) If the problem is on an external wall you could also rip it all out and build a timber frame, plasterboard, insulate and skim with gypsum, this will also give a gap between the new wall and the existing external, preventing cold spots which make condensation damp worse. Both would work and cost about the same all thing considered, but personally I would consider lime as that's likely what the original structure is made with so breathability is what you should have in mind. Many people get fooled into thinking sealing everything is better, but that's not the case with that era of build. Hope this make sense and helps.