Q: I came across your article about coating interior stone foundation walls, but my question concerns coating the exterior.
My 1890s house has a fieldstone foundation with remnants of a white material clinging here and there. Would recoating it be a good thing aesthetically and perhaps keep some of the “critters” out?
A: Having never seen your house, I wouldn’t know whether coating the foundation would be aesthetically pleasing. I imagine whatever you use would need to be in keeping with the age and architecture of the house.
What is this “white material,” and how extensive is “here and there?” Would it be easier to remove the remnants than recoating the entire foundation?
Obviously, whatever was used on the exterior was not maintained, and perhaps it was done consciously as the stuff began flecking off soon after it was applied.
If it were really ugly, I suppose you could hire a stucco contractor to recoat it and then waterproof the coating, thus reducing a source of basement moisture intrusion. Then again, some experts suggest that there needs to be an exchange of air from the outside to reduce moisture build-up.
At the time your house was built, contractors mixed excavated soil with lime and coated the inside of basement walls with it. In most cases, it crumbled after many years. If you felt the residue, it was sort of damp, which tells a lot about why the technique is no longer used.
Would coating deter critters? In my experience, they always find a way in.
Since you will more likely find such incursions at this time of year, you can help deter invasion by keeping the foundation clear of dead leaves and other debris to limit hiding and nesting places. Look for and seal up cracks in the foundation, even hairline ones, since mice and chipmunks can adjust their bodies to get inside.
Make sure rain and melting snow drain away from the foundation. If water can find a way in, the critters will, as well.