We're finishing our old basement, and have run into some issues with our plan.
We have:
1910 House with limestone/mortar walls. Parged by a previous owner many years ago. We will not be messing with the parging., other than securing furring to it. The walls cannot be sealed water tight.
Space is a huge concern. We will be furring the walls with 2x4's turned flat. We simply cannot loose much space around the perimeter of the basement.
So far, we've:
1. Torn out the old slab, dug down 6". (Couldn't dig down any more then 6" due to lack of footings.)
2. Installed perimeter drain tile and sump pump. (Entire neighborhood has wet basement issues. Apparently there used be a stream that ran through the area. No amount of landscaping can solve the issues.)
3. Installed new water main and sewer. Roughed in all plumbing that will go under the concrete floor, etc.
4. Installed dimpled membrane against interior of stone walls, with dimpled membrane forming an "L" over the perimeter drain tile, allowing moisture entering and condensing on the walls to weep in to the drain tile. We plan to install furring directly against the dimpled membrane.
5. Covered the entire floor with 6mil vapor barrier and 2" of rigid insulation. (Taped all joints.)
6. Installed 1/2" pex tubing, etc. for in-floor hydronic heat.
7. Poured 4" of concrete.
8. Ground and polished concrete floor.
9. We're just starting to furring walls.
The problem:
After all the moisture from curing concrete, wet grinding etc., mold has begun growing between the dimpled membrane and stone/parged wall. Our hope was that the air space provided by the dimpled membrane would allow the walls to dry, preventing mold -- but the opposite appears to be true.
We're looking for options.
One thought is to cut the dimpled membrane down, so only 8" or so is exposed above the slab, then fur the walls using treated lumber. (The stone wall is very uneven, so there will be space between the furring and walls.) After furring the walls, use closed cell insulation the insulation and seal the walls, closing any gaps between the furring and stone. The problem here is that we're worried not allowing the interior of the stone foundation to breath may not be the best idea.
Anyone have experience with situations similar to this? Do we just have to accept that mold will grow between the old stone walls and whatever is applied to it, and just seal it off the best we can?
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