Fixing water intrusion in the basement’s southeast corner room

ONE OF THE TWO areas of known, active rainwater intrusion is located in the basement, on the eastern side, in the corner “furnace room” (B-04A). Sometimes this space is called the mechanical equipment closet. Anyway, during a few days of downpour, water percolates through the unfinished concrete wall in two places, and it collects in puddles on the floor. 

Wet spot on wall in corner.
Nearby on the left is a wooden post.
(As usual, click/tap on an image to enlarge it.)

I have not previously mentioned this case, because it pales in comparison to the previously discussed cases of water intrusion. Mainly because this case occurs out of sight of nearly everybody. Nonetheless, any such water still threatens the long-term integrity of the concrete, not to mention nearby structural wood. Below the jump, I briefly discuss a few considerations.…

Source of the Water

Where is the water coming from? Obviously from rainfall: between storms, the walls are dry. But how exactly is the water getting that far below grade, and why only in this corner of the building? I wish I knew! The shed roof that is attached to the main sanctuary building should be sending rainwater away from the building. 

Although some of the water seems to be running down from above the ceiling of this room, the area immediately above that room seemed to be dry when I tried to inspect it. However, it was difficult to access. Perhaps when the adjacent termite-damaged floor joists are repaired, we can make a closer inspection of where the water is entering.

Extent of the Problem

Here are two photos that Ruben took in February:

Efflorescence (the white powder) is evidence of longstanding water intrusion, as is the patch on the left in the 2nd photo.

The light in this room is dim, making it difficult to evaluate the condition of the walls properly.

Damage?

I am concerned about the integrity of the adjacent wooden post, which helps to support the floor joists above. A post that keeps getting damp is liable to attract termites (which it has already been treated for) and/or to rot.

I am also concerned about the possible corrosion of rebar inside the wall.

What to Do?

Presumably the concrete walls in this room should be coated with a waterproofing paint such as Zinsser WaterTite Ultra, which is said to be designed for basement concrete walls. A relatively inexpensive fix, although (as usual) the prep work is considerable: 

“Before painting, surfaces must be clean, dry and sound, and free of dirt, efflorescence, mold, algae, sandy mortar or any material that could compromise coating adhesion.”

Still, that leaves open a couple of questions:

• What if the hydrostatic pressure turns out to be greater than what this paint can handle? What will our fallback approach be?

• Can we do anything (practically speaking) to keep the rebar dry inside the concrete—and if so, what?

If I bring out a waterproofing contractor to bid on the façade work, I may ask them about this issue, too.…