# Forum Home Renovation Brickwork  Limestone Foundation Repair

## chromis

I have a brick (limestone colour rendered) house built on limestone foundations.  
Mortar between the limestone blocks and brickwork has erroded. 
About 20% total area needs repair.  
What is the right way to go about repairing these gaps? Should I just use a mortar (coloured limestone) to fix them? If so what render product and mix should I use?  
Or is there some kind of bonding agent I can mix in to make the joints stonger?  
Is there some type of coating to stop wear on limestone foundations?

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## ozwinner

> I have a brick (limestone colour rendered) house built on limestone foundations.  
> Mortar between the limestone blocks and brickwork has erroded.

  First of all welcome.  :Smilie:   
I would be more concerned as to WHY it has eroded.
Any quick fix will come back if the underlying problem is not fixed. 
Maybe its rising damp?
Or acid rain, acid rain has terrible effects on limestone.
MAybe you are watering plants too close to the house? 
Have you any piccys you can show of the affected area?? 
Al  :Smilie:

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## chromis

The house was built in the late 50s and I have noticed the limestone under the eaves is in pretty good condition but where it isnt the rain must of eroded the mortar?  
Ants are living in between the cracks, so I guess they have moved the crumbly mortar.  
There's no sign of rising damp inside, some moss on the affected limestone outside but not alot.  
There's no water from garden beds getting on the limestone just in areas from natural sources.  
Some of the downpipes need to be modified because they are directed onto the limestone and has eaten away part of it.  
I live 20min from Perth so I dont know if Acid Rain is a problem.  
I'll try and get some pictures.. 
Thanks for the welcome.. :Smilie:

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## ozwinner

> I live 20min from Perth so I dont know if Acid Rain is a problem.  
> I'll try and get some pictures..

  It sounds as though it might be acid rain. 
CSIRO did a study of Melbournes smog laden air, and found that the stuff drifts out onto the bay and then heads straight for Geelong.
Geelong is around 70 kms away from Melbourne, as the smog flys. 
All is not lost if it is acid rain, once the affected area has been fixed there are products you can apply to minimise the acid. 
Al  :Smilie:

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## chromis

I havnt been able to get hold of a Digital Camera yet so I cant show you any pics.  
I am rendering the wall in question as well. The previous owner had 3 of the external walls rendered in a limestone colour and left the 3rd side wall, possibly because the plumbing made it difficult to render it. Maybe it was left out to cut costs because he renovated to sell.  
Anyway! I used a mortar premix to fix the brickwork before the render goes on and I have left the foundation limestone to work on later. I can be absolutely sure that the brickwork is not affected by rising damp and nor the limestone so I thought it was ok to go ahead with a render.  
I read all the posts on rendering and they are all correct. It's really difficult to do. But since it's a side wall on the unseen side of the house it doesnt need to be perfect. I used a sponge float in a circlular action to finish it off with a bit of texture which helps if you did put a spot on a little bit thicker. The work has blended in really well with the rest of the work as in the colour. Not a bad finish, not as good as the professionals work but not too bad either.  
I used the recommendation for render mix from cockburn cement.

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