Best way to parge exterior stone foundation wall

Question

I have a 1894 house with a stone/rock wall (limestone I think). The foundation is in decent shape for the most part but I would like to parge the exterior visible portion to give it a more modern look and to also make it easier to maintain. Currently each fall I go around and try to seal up any little cracks that developed through the year.

Anyway my plan is to dig down about 6 inches around the exterior. Then attach some diamond mesh to the rock wall. Use the first coat to fill to the level of the mesh, then skim coat that layer to give it a smooth look.

Questions:

1.) What kind of cement/mortor to use for parging?

2.) Can anyone offer a better suggestion on how to go about this?

I should mention too that part of the reason for doing this is that with a couple layers of siding (the most recent is LP smart siding) it sticks out a 1-2 inches over the foundation. I know I can't parge nearly that thick, but having a good 1/2" of parging would help narrow that gap.

Any input is appreciated.

Answer 1

I have used wire mesh attached to stone to stucco stone walls, I doubt your wall is moving after all these years but the mortar possibly could use some repointing but the stucco layer would take care of it by taking the weather.

Added to answer OP questions. The stucco mix is sand, lime,cement and water on larger jobs I pick up a trailer load of sand & bags of lime and Portland cement, for smaller jobs I pick up a couple of bags of pre mix. When Covering stone work I use expanded metal mesh because it requires less fasteners than wire, I have tried to use concrete nails but they don't hold well the reason we doing this in the first place was because the exterior had similar problems like you are having, a powder set driver just blew out chunks of mortar. What I did have very good luck with was tapcons screws, I was able to drill the mortar and if not overtightened they held fine and drilling the pilot holes was quick in the mortar. Where there were large stones at the corners I drilled the stone but that takes much longer than the mortar. We mixed our batches 5 gallons of sand about a gallon of lime, and a small coffee can of Portland cement maybe a quart , mixed by hand in a mud tray maybe 2'×3' about 8" deep. Mixing in small batches is important if just 1 person is applying just enough water so a trowel load when placed in a pile will stand up 4-5" damp but not wet, with the expanded mesh only 2 coats was needed the first worked into the mesh then the top coat. I am not a pro at this because I don't do it all the time but have done complete houses and a bunch of foundations where 1 job lead to 1/2 dozen more in the same neighborhood.

Answer 2

If you are “sealing up any little crack each year,” that means the foundation is still moving. Installing any cement coating over a wall that is still moving will crack, unless you can isolate it from the foundation.