stone wall problem

margi_g

my cousin owns an old stone cottage and has lived there for some years. I was doing some gardening for her and noticed there are gaps in the stonework in one wall.You cant see it directly,you have to hunker down hence that's why its only come to light when I was gardening.
I mentioned it to her and she said the wall there(in the living room) is always cold and that's why she has a heater behind the sofa.
I checked this wall again and it seems damp where these gaps are on the outside,but no sign of damp coming up the external wall. Dont think there is any damp proof course as its such an old place. Now the question is Should we get it rendered or would this mean the damp would be sealed in the wall . I must say I cant see any sign of damp in the internal wall . Bit unsure what to do. Would trying to fix it make it worse? Someone has told me lime render would be suitable for stone work outside Anyone got any ideas ?

FreeBear

margi_g wrote: »

Should we get it rendered or would this mean the damp would be sealed in the wall .

Would trying to fix it make it worse? Someone has told me lime render would be suitable for stone work outside Anyone got any ideas ?

Do NOT use cement or K-rend on the wall - As you suspect, this will trap moisture in the wall and lead to no end of problems.

I would suggest getting a bag of ready mixed lime mortar from someone like Ty-Mawr or Mike Wye and repointing the stonework. Wouldn't suggest rendering just yet, but if you do, use a suitable lime render.

Repointing is a fairly easy job - Soak the wall with plenty of water an hour or so before starting work. Knock up the mortar and place it on a small board (an old plastering trowel is ideal). Offer the board up to the wall just below where the mortar needs to go, and slide a small dollop in to the joint. Poke it with a stick (or a churn brush) to get it right in there. Repeat until the joint is full. As the mortar dries out a little, go back an tamp it in to close up any cracks that might be forming.

Cover the wall with a bit of damp hessian for a few days, and give it a light spray of water each day.

Do NOT mix any cement in to the mortar, and if you employ someone to do the job, feel free to shoot them if they try to use cement.

margi_g

Thanks for this advice.Makes a lot of sense

flashg67

I bought a house with cement rendered stone - right down to exterior ground level - has caused no end of damp issues. I've hacked it off for now to above the internal floor level which has definitely helped. I agree, would avoid cement render at all costs and try the lime pointing for now. if there are large gaps, maybe fill with stone first if they're big enough

FreeBear

flashg67 wrote: »

if there are large gaps, maybe fill with stone first if they're big enough

That is a good point that I missed out - If there are some odd slivers of matching stone lying around, it wouldn't hurt to put a splodge of mortar in the gap, then knock the stone in. Fill the remaining gaps with a bit more mortar.

As you may have noticed with my use of technical terms, pointing in lime is not an exact or precise job :beer:

margi_g

Just as a matter if interest, flashg67, how long did it take to remove the old render from your house? I have been looking at the rest of this cottage and I can see the kitchen also has render round the stone on the outside and that definitely always smells musty in the kitchen

margi_g

how long did it take you to remove the render from your house? I am checking this cottage and there is definitely a problem with the kitchen exterior wall as well

Furts

I am not getting into an argument about lime, but one has to add a note of realism. Cement mortar is meant to be incredibly weak, and countless folks, including so called professional bricklayers use too strong a mix. If OP has seen an occasional hole here and there, which by definition cannot be big because it is between stones, then a weak mortar made from cement is not going to cause harm.

FreeBear

If it helps, I came across this vid some time back..

https://www.youtube.com/watch?v=DmWQ1X1jYOk

I'm sure if she can hack some loose lumps out of a wall and then plaster it, the OP could manage a little bit of pointing.

As for hacking off cement render - Have a look when Lidle or Aldi are flogging air tools. Grab yourself an air chisel, compressor, and a length of hose along with a pair of goggle. Makes removing render so much easier than attacking it with a hammer & chisel.

margi_g

thanks so much for this. It really is useful .Thanks so much foir taking the time to research this for me it is really aprreciated!

FreeBear

Decopierre Stonecoat would appear to be a mix of lime and marble dust - Although, being of French origins, it is not clear what else has been added to the mix.

For a regular lime render, all the ingredients can be sourced locally, so there is no need to go to a French manufacturer.