What's the right mix for rendering an internal stone wall

Question

I'm just contemplating a task for next week. I have a 250 year old cottage with stone walls. One of the walls in the kitchen is showing signs of rising damp (chemical damp coarse injected 25 years ago). I am planning on removing 2 foot of plaster from that wall and re-plastering it. The plaster is about 2 inches thick so I plan to use 2x1 inch coats of render with a thin skim of finishing plaster on top.

My thoughts on the render are to use a 4 to 1 mix of sharp sand and cement with some damp proof agent added. I also intend to leave a 2 inch gap at the base of the wall to try to minimise further damp problems.

Does that sound like the right strategy? Is that the right type of sand to use and the right mix?

Thanks for your help.

Answer 1

dont use cement on stone it holds water in the wall and damages it over time.

use a lime based render, NO cement, go to a specialist supplier in your area

use with sharp sand, not plastering sand

Answer 2

its too thick ...you could all ways fix a layer of newtonite lathe first ..this is designed to tank walls ...make them waterproof ..you fix with galvanized nails or plug and s***w it on ...then apply two coats of render mix ..you must use plastering sand ..not sharp sand ..you will never get a good fin ish with sharp make sure you scratch the first coat well ..48 hours in between coats ..4 to1 by weight ..not volume ...by volume its about 6 to 1    too weak !

Answer 3

Use 12 parts sharp sand, 4 parts cement, 1 part white lime. Add some waterproofer aswell.

This should be fine.