Protecting Foam Insulation
The basement of this house has leaked, at the floor/wall joint for 35 years. It's a poured basement, full height, sitting on a poured floor. The contractor who did it, did nothing to key the walls to the floor, did an improper backfill and outside drainage job, The soil here is tight clay. Fortunately we are on a hillside and the downhill side is open for any water that misses the floor drains to just flow out. That's background.
Late last fall I had a contractor dig out the whole foundation, clean, tar, inject the crack, put a new drain system in and properly backfill it. While he was at it, we added 2" pink foam board to the outside. The foam board that is exposed above the soil is my problem. It is bolted to the wall with Tapcon screws. The top edge was cut at a 45 degree angle and fit snugly up under the T1-11 sheathing. Exposure ranges from 2" to 4.5' as the ground slopes.
I need to protect the foam from oxidation, strong sunlight on two sides, and the abuse of lawn mowing, etc. A contractor (friend) suggests parging, but agrees that it's likely to just loosen and fall away because of the extremes of weather and temperature that will hit the south wall. We've also had the suggestion to buy cement board (Hardieboard) 1/2" and glue it with contractor's adhesive to the face of the foam. The bottom edge would be in ground contact, buried perhaps 3"; is it stable in that situation?
Any other suggestions are most welcome.
BTW, It's not clear which forum to post this in. If I've missed, please move it or tell me where to re-post it.
(Location: Berkshire Mts. very close to where NY, MA, & VT come together.)