Type of plaster / render for 1930 cavity wall lime plastered / rendered property
Anonymous user 03/03/2024 - 3.41 PM
Hi,
I have a 1930 property that is constructed with a 5 cm cavity using red brick (lime mortar) and lime plaster / render (tyrolean).
Some of the internal / external walls have been skimmed with modern plaster.
The walls need to be re-skimmed and the outside re rendered due to cracks, since there is a cavity can non lime products be used?
What materials should the plasterer / renderer used i.e. breathable / tolerate movement etc? Since I want to ensure the plasterer uses the correct materials, and can non breathable bonding agents be used i.e PVA / blue grit etc
Jon
Are you a tradesperson and able to answer this question?
Yes most of the new polymer renders and lightweight plasters are designed with the proper preparation to receive modern materials
Answered21 February 2022
0
Anonymous user
Most bag mix polymer renders are breathable and combined with fibreglass mesh will not crack.
People get hung up on Lime render but there are so many better, modern products available that out perform the 1800’s.
Baumit.co.uk have internal and external products to suit, that’s what I’d use.
Hi Jon.
The above will depend on how much your budget is. You can strip the walls to bare brick and start from scratch with either HLP (hydrated lime plaster) or insulated plasterboards (internaly) and Lime render on the outside but you'd have to paint with a breathable paint.
There are also renovation plasters out there (BAUMIT?)
Or:
Regarding the interior; it will depend on the condition of the surface. If the skim coat is intact, then you (or your plasterer) should be able to reskim. Tackle the cracks first and chase/mesh/bond if needed and pva (twice) and two coat skim. You can also use ThistleBondit pva, which regulates the drying time (better than BlueGrit).
Regarding the exterior, you can explore the possibility of putting EWI (external wall insulation). If the current render is not blown, you can add this on top by scrim and pin first then insulating panels topped up by the Silicon Render. Be warned that this is not cheap..
Best to get a few quotes and discuss it with the plasterers face-to-face.
I hope the above is helpful and at least you've got something to discuss when getting quotes.
Good luck
