Re-pointing stone and brick fireplace

5 Apr 2011
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United Kingdom
I'm looking to restore this old fireplace, I've raised a few other questions about it on this forum but this one relates to cleaning up the wall and re-pointing.

I've started scraping the remains of the old lime plaster off the wall and that's coming off quite easily.

What I'd like to know is, how much of the lime mortar do i need to / can i safely remove from between the stonework in order to expose the stone and allow me to repoint?

The lime mortar that's in place at the moment is very crumbly and appears to have been slapped on a bit thick, covering some of the face of the stones.

I just need a 'point' in the right direction so I'm not doing anything unsafe or causing problems for myself later down the line.


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If you want to remove the render face & expose the brick then fine but don’t start removing the lime mortar between the brick courses if it’s sound, all you will do is compromise the integrity of the brickwork when exposed to high heat. Lime mortar can seem a little soft but it’s usually sound unless you can actually poke it out with your finger nail. If you re-point the brickwork with modern mortar mix that is too strong, the heat will very quickly destroy it & it will fall off the original lime mortar base; it’s been there years, just trust it serves a purpose.
You can take a quite a lot of the mortar out from around the stone but I wouldn't go more than about 30mm back and if they start to become loose just point in sections with a hydraulic lime 3.5 NHL 1:4 with building sand
Thanks both for your replies. I won't be removing any mortar unnecessarily, I just want to remove the stuff that's obviously loose and then repoint that area. There are some bits which obviously need repointing as it has already fallen out so I'll concentrate on that first.

Going a little off topic, I need to clean up the bricks inside the fireplace which have heavy soot deposits on them. I've searched this forum and others and have seen people recommending such things as bleach, ammonia, vinegar, cillit bang and foaming bathroom cleaner.

Due to the age of the brickwork and softer nature of the mortar, is it unadvisable to use these sorts of products or will they be okay?
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Never used household products to clean brickwork before so can’t advise how successful they may be, especially on absorbent surfaces & I wouldn’t use neat bleach or ammonia. Proprietary brick cleaners may work but be careful as some are very acidic.

Blast bead cleaning would probably give the best results as the blast medium can be as coarse or as gentle as required but this may not be an option for you.

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