Stem walls commonly have deterioration that looks like this photo. Over time, it will continue deteriorating (pitting, chipping & flaking). This is a result of mineral deposits left on the surface as they evaporate. They usually enter the concrete from the soil and wick their way up to the exposed surface where they are deposited.
Many homes that are built on former farmland have mineral deposits as a result of the previous farming activity. Gilbert, Maricopa and parts of the west valley are common areas of high deposits.
This is a difficult problem to deal with. There is no way to completely stop the mineral migration unless the concrete can be sealed from all sides including the bottom of the footing and the inside of the stem wall under the house. It’s the chemical process that nature uses to break down rocks into sand.
We have developed a mineral mitigation plan to deal with this problem! First, the most important thing to do is to improve the drainage around the perimeter of the house. This will reduce the amount of moisture that transmits the minerals.
Our mitigation plan goes something like this:
- First excavate next to the stem wall down to the top of the footing.
- Let the stem wall air out for 7 days or longer.
- Return and grind the deteriorated concrete to a depth where the concrete paste is full strength.
- Leave at a CSP profile of 5-7
- Apply a 3 part epoxy bonding agent and anti-corrosion inhibitor
- Then apply Low shrinkage polymer reinforced cement with fiber reinforcement
- Last the entire stem wall should be sealed with a siloxane sealant
- Backfill the wall and grade to slope away from the house.
Keep in mind this is not a cure, since nothing can stop nature. But we can slow it significantly. This as it turns out, this is the best mitigation plan available on the current market to remedy this problem. Depending on many factors, the repair may last many, many years.
If you are seeing signs of a sulfate chloride attack on your home's stem wall, we would be happy to come & take a look. As always, initial inspections are free for Arizona Homeowners.