Lime plastering

[cornishcarpenter]

hey guys,

Got to plaster 2 walls, old cornish stone, they are slightly damp, the lady has found where the damp is coming though and needs repointing which is going to be done at a later date.

I have suggested to her to use a lime mix as this is breathable and good for old cottages like hers. Only used it a few times at college and was wondering on a more detailed explaination on mixing and using it?
thanks

 

[deepbluearcher]

I have recently been doing a clay lump barn conversion and used lime exclusively.

I found a mix of 3:1 works well - thats 3 parts sand to one lime - Mix up as much as you need and leave it for a few days minimum - if its covered it won't set and can be damped down to the consistency you need/prefer to work with. Damp the wall and allow to dry slowly if possible - It will shrink so the base coats will probably crack. An aditive such as straw or hair is always good - the grade of sand will depend on the finish you want. I found that coarser grains give better results. My preferred mix for render is 2 parts sharp 1 part building sand and 1 part lime. A posilan can be added if it is going to be exposed to severe elements.

Don't be tempted to add cement as some will advise you - you only need a small amount to ruin the breatheability of it.

Avoid overworking it on the wall with the trowel as it brings all the lime to the surface and leaves a weak sand mix stuck to the wall - use a cross grain float to smooth it then a quick rub with the trowel to polish it.

Mike Wye has a shop specialising in lime stuff - he is in the west country somewhere I think - Try googling it.

Hope that helps.

 

[woodgnome]

If you want a really good book on working with lime -check out "Building with lime" by Stafford Holmes andMicheal Wingate,published by Intermediate Technology publications-It will answer any question on this subject