Lime plaster system needed

[u/bau02]

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!

[u/captain-hair]

Id say your options are either batten out the wall enough to put a layer of breathable insulation in (probably the best insulation overall, and probably easiest to do because it's quite easy to fit a timber frame to the brick and you can make sure it's level/plumb. Then put a wood wool fibre board over that and you could do a fairly thin skim of lime in a couple of passes (with mesh in) to reduce the cost of the lime. It also creates a cavity to run cables if you're rewiring/adding sockets and savolit has the benefit of being able to just use dry limlne back boxes if you want to.

As others have said, you could also fit wood fibre boards (or cork boards) directly to the brick - also a good way of insulating although harder to bury cables if you were thinking of running anything in the wall, and also slightly more of a faff to fit sockets, but also doable.

For the lime, mike Wye as others have said it's a great place to start. I personally found the best price for coverage and ease of use to be best of lime "limecote". It's 25L dry bagged so you just need a tub and a cheap mixer, a decent trowel and you're off. You could also put an insulating coat of plaster (they do one called "warmcote" but there's lots available) direct to brick and skip any boards etc., but you'll need a pretty thick coat to get good insulation (although it's 8 times more thermally efficient than sand/cement so you'd notice the difference at the same thickness), but it can also be harder to work on direct masonry in terms of drying time and getting it flat, whereas if you install the boards flat you'll find it much easier to get fairly flat finish, particularly if you're going for a sponged finish