I had literally not had the full den and bathroom areas covered in subfloor for ONE DAY when intense overnight rains (and some bad drainage) scared the pants off me. I came down to grab a tool and found water on the floor seemingly seeping out from under the sub floor. I ran around to check the windows for leaks – nothing – and the walls for cracks – again nothing and the ceiling for drips – nothing again.
I eventually figured out that it was seeping in from the south west corner through the wall and then running along the floor under the new sub-floor until it got to the back basement. Then it ran down along the floor slope and around to the floor drain:
The good news: it’s an easy fix. I just needed to re-grade the ground outside the house so that water can flow away from the house rather than forming Lake Togstad just two feet from the corner of the basement.
The better news: the sub floor system worked perfectly allowing seeping water to flow freely out from under and around to the drain just as it ought. I brought down two fans and a dehumidifier and the basement was dry and back under 50% humidity in a day.
I’d noticed deteriorated paint in that SW corner before but after the flood it literally bloomed with mold in all the places where the paint had flaked off. NOT cool. I scrubbed the wall of paint flakes and cleaned off the mold with vinegar, then primed and painted it with exterior latex paint. This is not a waterproofing measure – I’m fixing this water infiltration issue from the outside – but it will seal the surface of the concrete so that when there is more moisture in the concrete wall there won’t be an exposed surface for that mold to form on.
This water infiltration did give me quite a scare. But in many ways it was perfect timing. If this had happened after I had put up the insulation I wouldn’t have been able to figure out where the water was coming from and it would have been harder to ID and fix the problem outside. As it was I quickly pulled back some of the flooring I’d just put down. Here is Roxie supervising from the stairs while I pulled up the last row of DRIcor panels and flip them upside down to see exactly where the water is coming from.