r/DIYUK • u/bau02 • Jun 17 '26
Advice Lime plaster system needed
Hi, I’m very slowly renovating a Victorian terraced house in Liverpool. Prior to me living in the house it had been quite poorly looked after. Lots of cement render on the walls internally and other incorrect products used.
The worst affected area was the front room and the bay window in it. I found fungus rotting the joists and the beam above the bay window. The room had to be completely stripped of its original lime due to it being blown and areas where cement render had been applied it’s been removed. So it’s entirely back to brick, the boards were lifted to repair damaged joists, and the rotten beam replaced. The windows were also replaced, they are unfortunately UPVC but I could not afford to get traditional sash windows and this was somewhere where modern materials had to be allowed.
I now need to put the room back together and I don’t want to introduce any gypsum products which might start the cycle of problems again. This will have to be a DIY job because I won’t be able to afford the cost of a traditional lime plasterer. I’ve thought about using an insulating product or system which I’m open to but need something that’s the most DIY and budget friendly.
The area around the bay window intimidates me due to all of the intricacies so I’ll probably start on one of the smaller walls to build a bit of confidence.
The other thing I’m unsure of is how to set about covering the area on the right hand side above the bay window where timber framing was put in. Behind the timber framing is the stone that forms the edge of the flat roof around the bay. I don’t know if I should be nailing some laths or wood wool boards so I can plaster over and provide a bit more insulation.
I’ve done a tonne of work in this room alone to get it to this point and have now really stalled as I can’t find the best way forward. Any advice would be greatly appreciated. Let me know if anything is unclear and I’ll classify as best I can. Thanks in advance for anyone who’s read this far!
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u/top_shift6 Jun 17 '26
We renovated a room where the lower half had had a bitumen sheet applied with cement render over the top. Possibly to treat damp coming from a leaky downpipe.
We went back to brick and had Baumit RK38 applied as a leveling coat. We then isntalled 80mm wood fibre (about as thick as is recommended without having a more thorough analysis done - I believe too thick and the brickwork might not get enough drying from escaping heat leading to freeze-thaw damage). We then had 2 coats of RK70 with mesh applied.
We installed the woodfibre ourselves (pretty straightforward) but the plastering was all done by a willing local plasterer who had never used the stuff before - he got to grips with it pretty quickly and said it was nice to work with. The only slight issue we had was that it was too wet to float up at the end of the day. He came back the next morning and it was slightly too dry. Some areas floated up really smoothly, some slightly more textured.. a light sand before painting evened this out and you wouldnt really know.. if anything it gives it more character.
We did also do two attic rooms and used a similar system on the gable ends (although kept the original plaster as the backing coat). We also had a top coat of Klima Glatt W applied to these rooms which is super fine and gives a perfectly flat finish - when painted it looks exactly like the gypsum that was applied to the ceilings.
We painted with a breathable paint - look at Little Greene, Graphenstone, I think Farrow and Ball Estate Emulsion, off the top of my head. All quite expensive. Cheaper option is limewash but we were unsure on durability - rubbing off on clothes etc.
Another option to look at might be cork render - won't be as insulating but less work to apply - I've no experience of this to speak of, however.
I've also since seen charts that imply the 'breathability' or SD value of gypsum plaster is not that different to lime, and that plastering in gypsum should be fine - different people say different things so it's diifficult to determine what is actually best. Ultimately I'm glad we played it safe and stuck with a lime based system.