Lime mortar repointing project

[iang]

You can also try an angle grinder carefully along the centre of the joints to make it easier with the hand tools. It's usually a case of seeing what works best on the job. Problem with a hard mortar on a soft stone is that bits of stone often come away with the mortar.
All you do is damage limitation, and make it look good with the new pointing. Picking a good colour for the mortar can help improve the looks of the wall.

Hi Stuart. Sorry, another quick question if that's OK. I've noticed as I'm raking out that there are quite deep voids behind the stones. The vertical joints between the stones are only 1-2 cm but if I push a peice of wire behind it goes 6 inches behind the back of the stone. How would you recommend dealing with these voids. Thanks again in advance.

 

[Stevers]

Can't speak for Stuart, but my pointing is done with a Marshalltown tuck pointing trowel - pushing the squashed mortar from my plastering/finish trowel. This is a technique usually used on brickwork, but it works well for me on stone work. It's a method that keeps the wet mortar off the face of the stone, and is capable of deep penetration, though having voids in stone walls is normal, and may even be helpful. I reckon there must be enough connecting voids in my walls for a little party of wood mice to make it all the way up into the loft, as there was no sign of them in the house.

 

[stuart45]

Hi Stuart. Sorry, another quick question if that's OK. I've noticed as I'm raking out that there are quite deep voids behind the stones. The vertical joints between the stones are only 1-2 cm but if I push a peice of wire behind it goes 6 inches behind the back of the stone. How would you recommend dealing with these voids. Thanks again in advance.

Ask as many questions as you like iang. The vertical joints, [cross joints], are often only half filled on brick walls, or some stone walls because of a method known as tip jointing, where only the outside of the brick is mortared. In theory all the joints are full, but in practice this is not always the case. The half filled cross joints on a solid wall are a weak spot that allows moisture in and to gather in the voids.
I normally use the same sort of method as Stevers. As I only work on an hourly rate nowadays, I just keep pushing the mortar in till it fills up.
Ideally, with deep voids you should build it up in layers to keep down the shrinkage on the face.