Following the mold remediation and ventilation addition described in my Garage Renovation – Part 1 post, the concrete foundation needed to be repaired. As I am not a mason and have limited experience with concrete work, the Internet had to be my expert. After hours of online research, the best course of action appeared to be (1) application of a penetrating sealer and strengthener [RadonSeal], (2) application of a chemical bonder to make new concrete adhere to old concrete [WeldCrete], and (3) application of a fortified concrete resurfacer [Surface Bonding Cement]. There are multiple vendors selling products for each of these steps. My selection was informed by countless YouTube videos showing actual experts using these particular products and explaining how they differed. This isn’t to say that other products wouldn’t work just as well.
Step 1. RadonSeal. After cleaning the concrete wall with a brush to remove loose material, you wet the wall and then spray the clear liquid RadonSeal. As the water dries, the RadonSeal is drawn into the concrete.
Step 2. WeldCrete. This product goes on blue. For this reason, it is easy to see what you have and haven’t covered as you apply it. I’m sure I put it on a bit thick for what was actually necessary. Keep in mind that I am not a professional — I just use professional tools.
Step 3. Surface Bonding Cement. There were several possible approaches I had considered for this step. One was to form in the wall and pour the concrete, which would have produced a straight wall but required a great deal of form building. The other option was to hand trowel. In the end, I hand troweled the side walls and formed only the back wall. The product I used is not widely available but highly recommended. It contains a fiberglass filament and can be waterproof when applied appropriately.
All of this work was completed before the rainy season, so I can now attest to it accomplishing the intended job. There was no further water infiltration through or around the foundation even though the rains were quite heavy this year.