April 10, 2009: Drainage around the foundation and garage support piers (Updated)

Began filling in the space around the foundation with a mix of rocks and soil to improve the moisture seal of the foundation and improve drainage around and away of the foundation. Basically, if water can't drain away from the foundation *alot* of water pressure can build up against the wall and eventually, water will push its way through the wall. So it's important to channel the water down and away from the foundation walls. The following is actually a little more complicated than it appears, e.g., the rocks aren't there to look pretty - they're there because water will flow through those gaps better than through compacted soil. For a little more context see this pdf or this wiki entry.

You can pretty clearly see where the stones are lined up against the base of the foundation to help waterflow in this picture (the black stuff is the foundation seal). I believe there's also 4-inch perforated drain pipe beneath the stones (I saw them laying around, but like a doofus, I didn't take a picture) to further enhance the water flow away from the foundation.

Here's a closer view of the stones around the foundation. There's a permeable fabric over the top of the stones. I assume this is to somewhat limit the penetration of the soil into the stones which could clog water flow.

Against the garage-side wall (or more specifically against the main level bedroom East(ish) wall), fill dirt was placed over the stones. Note that in addition to sealing the foundation wall with tar, small treated boards are also installed. Foundation sealer tends to dry and crack and this can help protect and extend the life of the seal.

To help drainage along the East wall, there's actually a drain channel through the garage (top and right in the picture) covered in stone and the soil-fabric. Additionally you can see a couple support piers for the garage floor going up (soil has a nasty habit of settling and doesn't make for a long-term stable base to hold up a few tons of car)

A view of the garage from a little further away from the hosue on the driveway.

In addition to the backfiling around the foundation, they were also digging around and under it! (In addtion to the trench that I think is underneath the stones). In context, this hole is presumably to allow septic lines to flow to the outside as the septic tank site is relatively close to where this hole is located. And though you can't see it here, there's a matching hole on the other side.

Update

Went back to the lot and took a couple pictures I should've taken before to better illustrate the drainage.

The perforated drainage pipe that is placed beneath the gravel. The holes allow the water to flow into the pipe and then be funneled along and then away from the foundation.

The drainage pipe poking out (but taped over for the moment) from underneath the gravel and the soil mesh.