To point or not

[sarahj]

Hi,
Still working on taking off cement plaster from damp stone wall in sitting room, and planning on pointing (lime of course) and then limewashing a few coats, and then leaving for two or three years while other walls are done the same, and then lime plastering.

However, bro (a plasterer of old and new materials) says that it would be better not to point to give plaster a better hold. this makes sense, but I want something more finished looking to live with until I plaster. Is he right, or can I point?

Sarah

 

[Mark]

you can point.

There was some research done on this (by a reputable bod - just cant quite remember who) and its a bit of a myth that you shouldnt point.

researcjmay have been on rendering- but same thing.

 

[Schoolmarm]

Agree. Point it.

There will be different depths of render otherwise which isn't good.

 

[PC]

Hi sarahj

If you intend to render at a later date.... why waste time and money repointing. You can produce a reasonable finish (to look at) by simply raking the mortar joints and leaving as a temporary finish.

This would also aid the drying process and of course provide a good key for the future replastering.

Repointing is very labour intensive, unless of course you intend to do this yourself!

Good luck

PC

 

[Gervase]

An essential part of rendering/plastering on old stone is dubbing out, which is filling in gaps, dips and voids to ensure that the subsequent coats go on at roughly an even thickness (to ensure even drying and carbonation and to avoid shrinkage and cracking). And dubbing out is merely repointing by another name. You don't have to be neat - just hurl the mortar at the gaps and cracks to fill them, press home then smear and strike off the excess with a round-nosed gauging trowel. It doesn't take long, and means that the subsequent rendering or plastering will be easier and quicker. It's very easy to do yourself and quite satisfying. So I'd say, yes, do repoint/dub out before rendering.

 

[BMcD]

The raking out of mortar joints prior to plastering depends on the porosity of the wall. On low suction, dense or smooth backgrounds joints should be raked to a depth of 10mm to provide a key and if the walls are of large stones with low suction then the stones should be picked or have a spatterdash applied to provide an adequate key. Higher suction background and rougher backgrounds may not require raking or spatterdashing. Successful plastering depends on a good key and control of suction

 

[Penners]

I was always taught that it's rude to point.

The above is an extract from a new publication, entitled "The Wit and Wisdom of Penners". It's a slim volume.

 

[michael]

Not sure if this is really relevant to your plastering/pointing dilemma but I posted this link the other day in relation to stucco work and its repair

http://www3.westminster.gov.uk/spgs/publications/Stucco.pdf

Page 8 of 15 - ‘Recommended repair procedure’ advises:-

“Wire brush brick face and clean out the joints to provide a minimum 15mm key”.