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Stone Foundation

House built 1880 Upstate New York

Issue- hydrostatic pressure water infiltration, basement always damp limits use and has mold and mildew.

Proposed resolution drain tile at base, waterproof coat foundation.

I have dug up a portion of foundation (Purple sandstone and gray limestone) to footer 5 1/2' deep to expose stone and some mortar is loose and missing (20-25%) shallow voids nothing seems to go all the way through and stones seem solid.

I am trying to find a product I can use to repoint without damaging existing mortar or stone. I have been told products readily available at box store are too hard and may cause mortar failure or cracking or splitting of stone.

Non-hydraulic lime...or... Lime putty...or...High Calcium hydrated lime mixed with 2.5 parts coarse sand

I can not find and local suppliers are clueless.

Also what will be safe to waterproof wall assuming use of lime mortar.

Re: Stone Foundation


I still need assistance.

Can reach me at [email protected] or reply to this post.

Re: Stone Foundation

Unfortunately I don't have an answer for you. But I was hoping someone would respond. We have a 1929 house with a stone foundation (in Washington State). We don't have serious water issues, but definitely some on very rainy days.

I hope someone responds...good luck!

Re: Stone Foundation

Similar problems here.

I've read that mixing mortars can cause problems - perhaps further deterioration of the original mortar, but the biggest concern that I've seen repeated is that today's mortars are portland based and often mixed to be harder than the brick or stone it is helping to bind. I wasn't able to find a lime-based mortar, although I bet there are people and info out there on how to make it. The approach I've been taking is to remove the deteriorated lime-based mortar (scrap it until it doesn't easily crumble) and then I've been replacing with a type-S (below grade) mortar mixed with sand (3 parts sand to 1 part mortar mix). This is working very well for me. My reasoning for heading this way is that the mortar I'm adding is certainly not going to be stronger than the stones in my fieldstone foundation; and some mortar (even though it isn't lime-based) has got to be much better than no mortar at all.

Incidentally a repair was done to the foundation of my house about 20 years ago. When they did this work it looks like they used straight concrete. In some places (which I'm repairing) I can break and pull it off in chunks. The lime-based mortar underneath the concrete repair is just fine in some spots - it is sand it others.

Finally, I'm a bit worried about water proofing my final work. I've dealt with the water issues - this should no longer be a problem, but in sealing the walls I'm worried that the wall could not breath and release moisture if any found it's way into the wall. Something to consider perhaps.

Good luck..

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