A Closer Look at the South Side Water Intrusion

YESTERDAY, thanks to our gracious neighbor, I got a closer look at the exterior south wall.…

 

The one advantage of the physical damage that I described yesterday is that it enables us to see what’s behind the stucco on the lower, thicker part of the wall. It appears to be the foundation wall that emerges from the basement. (The wooden frame wall must be resting on top of it.) And rather remarkably, I see no evidence that this concrete was ever waterproofed with some kind of coating (usually a black tarlike substance). Rather, the stucco seems to have been applied directly to the concrete.

Now, it happens that stucco freely admits moisture, which would mean that the foundation wall predictably gets damp during a heavy rain. (Paint does provide some protection — but maybe not so much when it’s 14 years old, like our paint is.) After all, rainwater runs down the outer wall and soaks into the ledge and the lower wall — which are both permeable surfaces. And that moisture presumably travels inward, both up into the frame wall (by capillary action), and down into the basement wall (by gravity). Not good! 😲

Farther up the wall, behind the stucco, the frame wall was presumably protected by an internal moisture barrier — such as a layer of tar paper. However, back in 2011, I spoke with a consulting engineer (regarding a stucco building elsewhere) who contended that in structures more than 50 years old, chances are high that the moisture barrier behind the wall has deteriorated. Hence it should not be surprising that we have been experiencing water intrusion through our walls in some places. 

A Survey of the Wall Section

Here is a series of photos that move from east to west along the wall, following the direction of downward slope to the sea. There’s intentionally some overlap in each photo. The tape measure in the first photo shows that at the easternmost edge, the top of the foundation is 28" above grade.

As I noted last week, one consultant (who was apparently unable to view the situation up close) suggested that the problem was a leaky joint between the asphalt pavement and the wall, combined with an accumulation of water against the wall. However, that joint appears to me to be well sealed. Furthermore, the pavement already noticeably slopes away from the wall in the vicinity of our water intrusion problem. So at the moment, I am not inclined to adopt those two suggested remediation measures.

Pavement slopes away from the wall

Still, I wonder why the evidence of water intrusion is so pronounced in the eastern half of the sanctuary only. The considerations described above would seem to apply to the entire length of the wall.

Structural Integrity

Meanwhile, I’m concerned about the long and deep cracks at the base of the post that had caught my eye last week.