Rubble Wall Best Practice

[Jakey]

Hello all!

It’s that favourite topic again…

I have a recently taken on a C1700’s cottage with an internal rubble wall. The other walls are double brick no cavity as you would expect. I have had many a builder come in and tell me to batten and plaster board it, but I really don’t think that’s right. Or dot and dab plaster board.

My plan is to fill gaps with rubble and lime mortar. Then lime plaster the entire thing. Hoping to plaster myself (is this unrealistic?)

It was sealed over with concrete, cement, plastic tanking, and more plaster. It’s currently beading with water (I’m assuming it’s finally breathing and slightly hindered by a non-breather roof membrane directly above).

Does this sound like the correct course of action? How ‘clean’ do these stones need to be? There are patches of cement/concrete proving difficult to remove (see beigey section in photo) and I don’t know if the plaster will be fine regardless of these. I don’t want to bash and disturb it any more than is necessary.

Also how ‘dry’ do these need to be before plastering? Will it continue to breathe despite the levels of moisture beading on the surface?

Photos attached if that helps.

I’m in Glastonbury.

Look forward to learning from you all!

 

[joe_thomas]

Hi @Jakey

Lime plastering is definitely something worth trying - I've completed the ground floor of our stone cottage now, and I'm really happy with the process and finish.

Get your stuff from https://www.lime.org.uk/ , they're incredibly good people with excellent advice too.

This playlist on YouTube gives you an excellent step by step guide:

It's not easy, it takes practice, good tools, patience and more patience but I found it worth while.

The wall should be free of any loose bits and pieces, brushed down and all cables/fitting fixed in place. Dubbing out with medium lime plaster will help level things out before applying your first full coat.

Any questions let me know!

Joe

 

[Kearn]

Depends what your goal is - internal wall shouldn’t be as challenging as external, so it’s not got major moisture to handle, except what’s coming up from the ground and the moisture you’re generating in the room.

If it’s wet, then it will be slow to dry fully, rule of thumb an inch per month. You can plaster onto damp walls, but too much moisture in the substrate and the lime just won’t go off ready for the next coat.

Assuming it’s just aesthetic, then you could save a lot of time, money and effort and just bag rub the wall, lime wash after.

If you’re after a flat finish, then you’ll need to spend time daubing out any major cavities. Ordinarily, I’d say use hemp lime, but not if the wall is too wet as the hemp will rot. But you can go deep in one hit, unlike standard lime. Alternatively, get some actual daub, although harder to source now. Yes, fill up big voids with pieces of stone / flint / bricks / broken clay tile so you minimise the thickness of plaster. I wouldn’t worry about the odd section of stubborn cement, just make sure it’s got a good mechanical key scratched into its surface. Give it a good brush down with a churn brush before you start to remove loose materials and run the Henry brush attachment across the surface.

When you say beading, it sounds more like you have a cold wall and moisture condensing on the surface rather than moisture escaping from within.

You’re right, avoid the standard builders as they don’t understand!