Removing cement-based repointing

xeres · 6 May 2019

Hi all

Looking to remove the ugly cement pointing that will damage the stonework of an 1860s Terrace house.

Pointing has been thickly applied over a traditional lime pointing. This will cause the stones to spall and damp issues within the property.

Much of the pointing is already loose so is easy to chip off. Some of it has been done recently and is stuck fast. Interested if anyone has any tricks on removing this without damaging bricks. My obvious concern is the effect of acid on the stone.

Many thanks

^woody^ · 6 May 2019

You need to avoid common cleaners based on hydrochloric acid, as this can cause staining and is too harsh for many natural stone. Other than that, do a search for stone cleaning chemicals - if you know the actual stone, that will help.

xeres · 6 May 2019

^woody^ said:
You need to avoid common cleaners based on hydrochloric acid, as this can cause staining and is too harsh for many natural stone. Other than that, do a search for stone cleaning chemicals - if you know the actual stone, that will help.

Thanks. Trying to upload pictures but it doesn’t actually post them which is annoying

stuart45 · 6 May 2019

Limestone would be the worst as the acid will react more with calcium carbonate.

xeres · 9 May 2019

Pic showing the newish cement mortar in left. To the right is old cement mortar over original like mortar, which has evidently failed and is easily chipping away, mostly with me pulling using my finger.

Anyone who can tell me what stone it is?

^woody^ · 9 May 2019

Looks like sandstone

lostinthelight · 9 May 2019

xeres said:
Hi all

Looking to remove the ugly cement pointing that will damage the stonework of an 1860s Terrace house.

Pointing has been thickly applied over a traditional lime pointing. This will cause the stones to spall and damp issues within the property.

Much of the pointing is already loose so is easy to chip off. Some of it has been done recently and is stuck fast. Interested if anyone has any tricks on removing this without damaging bricks. My obvious concern is the effect of acid on the stone.

Many thanks

Running a narrow disc along the centre of the pointing then chisel from the edges towards the cut, works for me most of the time.

xeres · 9 May 2019

lostinthelight said:
Running a narrow disc along the centre of the pointing then chisel from the edges towards the cut, works for me most of the time.

Super helpful post, thank you.

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Removing cement-based repointing

xeres

^woody^

xeres

stuart45

xeres

^woody^

lostinthelight

xeres

DIYnot Local

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