This Old House-Part 2: Actions
In part 1 of this series, I described problems in our old house this past winter: gallons of water flowing into one corner of the basement when we had heavy rain falling on a roof and yard covered by ice and snow in Madison, Wisconsin. We had 14 days to figure out how to prevent water damage or cancel a long family trip away from home.
A fix, undone?
The construction of our 100-year-old foundation does not follow accepted practice: the top of the foundation wall is at roughly the same level as the adjacent driveway. Standard construction would have the foundation wall higher than ground or driveway level (12 inches or more.) When we first moved into our house 30 years ago, we had intermittent dampness in the northwest corner of the foundation, the area where our 2019 problems were most severe.
More than 15 years ago, we had our general house contractor install an aluminum L shaped-barrier on the top of the foundation adjacent to the driveway. The opening of the L faced the driveway. The vertical part of the L went up under the siding; the horizontal part got riveted to the top of the foundation. The metal to driveway interface was caulked to be watertight. The barrier and caulking prevented water from getting between the driveway edge and the foundation and then finding its way into old cracks in the foundation wall.
Since the installation of the L fix, we had no major water problems until the three big rains in February and March 2019.
I suspected that the expansion joint between a new driveway section and an old section allowed water to reach the foundation. In March, we had water seeping through the foundation wall adjacent to the expansion joint location shown in the photo at the top of this post. This seepage was eight feet away from the biggest leaking crack. During the second rain storm, I probed this expansion joint with a wire. I stuck the wire more than 8 inches straight down near the foundation-driveway interface. I jammed foam backer material into that expansion joint and reduced the water seepage almost to zero inside at the adjacent foundation wall.
The next day, I got a better view of the expansion joint and a closer look at the L shaped barrier. I found multiple gaps in the metal sections and no caulk between the new concrete the metal L base. When the old driveway sections were replaced, it looks like the caulk seal got broken and the joints between pieces of the L metal barrier formed gaps. Rain storms in the late summer and fall in 2018 after the driveway work had not caused any water in the basement so we had not paid close attention to the caulk seal and metal joints.
The photo shows a void (1) between the new driveway section (2, grey) and an old driveway section (3, brown) adjacent to the foundation; foam backer rod jammed into the expansion joint (4); gaps and lack of caulk along the metal to concrete interface, disrupting the 15 year-old L intervention (5).
Getting water away from the foundation
1. I used a snow-rake and then a shovel to remove 10 inches of compact snow from our roof so that the total volume of water from another rain storm would not be increased by snow melt. Back on the ground, I moved the snow tossed from the roof away from the foundation to the back of our garden and to the boulevard adjacent to our street.
2. I opened up the gutters at the drain holes by melting the ice with a couple of stockings filled with calcium chloride. I dug out most of the ice from the remaining parts of the gutters by hand after a bit of thawing with a few more stockings.
3. I replaced an extension to one downspout that had frozen, been buried under four feet of snow accumulation, and cracked when I tried to re-position it to get proper flow a week earlier.
4. I added soil to the small area in the northwest corner of the foundation to slope rain away from the corner and adjusted flow from one downspout onto a splash block.
Repairing the driveway/foundation barrier
1. We caulked the expansion joint where I had jammed the foam backer rod.
2. We caulked the interface between the L-shaped metal and the driveway and the gaps between sections of the L-shaped metal.
Testing the fixes
After the third rain storm, we hoped for a heavy rain to test our fixes before our departure date. No luck—just some drizzle that didn’t lead to any basement water. I poured a couple of gallons of water onto the caulked expansion joint. Still no basement water. I decided against using my garden hose to spray water on the driveway. The metal to driveway caulk was still drying slowly in the cold outside air and I didn’t want to disrupt the seal.
Backups to our fixes
Our fixes seemed like they might prevent another basement flood but should we leave the house for 10 days?
We added three components to contain water damage if the fixes were ineffective.
1. Containment pond: We built a pond to contain water that might enter through the legacy crack. We put a small transfer pump into the pond and ran the drain hose to the floor drain. The pump would turn on if the water got to be 1/4 inch deep in the pond and turn off automatically once the water level dropped to 1/8 inch.
2. Remote sensing: I got a wireless water sensor that notifies my phone if it detects moisture and a wired video camera to allow a remote view of the problem area.
3. A neighbor with a key: we got a neighbor to agree to come over if the sensor detected any water and to mop up any water that escaped the pond.
Here’s a picture of the pond.
The photo shows the crack associated with the big volume of water seen in storm 3 (1); the water sensor’s detector (2), adjacent to two ping pong balls tossed on the floor to act as a visual marker of the ‘dry’ state; the transfer pump (3) with hose running to the floor drain.. The white tape on the floor is water-proof tape that makes a water tight seal between the concrete basement floor and plastic sheeting, which was caulked to the walls with silicon caulk. The blue painter’s tape held the plastic in position while I worked to get the pond water-tight.
The picture is from the remote video camera the afternoon we left for our trip, with a bit of fish-eye distortion at the edges of the image.
What happened: No water in the basement
We took our trip; there were only a couple of days of drizzle in Madison during the ten days away. On our trip, I checked on the basement every day; the water sensor never sent a message.
We could have rolled the dice and left home without the backup actions in place. The backup steps acted like insurance, reducing worry while away.
Back in Madison, we expect heavy rains this week. I left the basement pond and sensor still in place to see if the mitigation system works as intended. I’ll update this post with results.
In Part 3 of this post, I’ll summarize lessons from our basement that touch on systems thinking and problem-solving.