Waterproofing Stem Walls for a Custom Home
Today, we are doing prep work and waterproofing on these stem walls. You can see this on a custom home we’re building in Middleton, Idaho, and I want to show you how it’s done. If you’re having a house built or getting ready to build, ensure you’re doing it correctly.
Snap Ties and Cold Joints
We’re down here next to this footing and stem wall, and you can see the caulking on the wall here. This sealant waterproofs the snap ties, which hold the form together and are visible on this side of the wall.
Moisture tends to chase these ties through the wall, causing leaks on the other side. It’s especially common at the cold joint, where the footing meets the bottom of the wall. Water can sit on the footing, run into the stem walls, and eventually puddle inside the building.
Critical Areas to Waterproof Stem Walls
When pressure washing this wall earlier, water ran off the footing and pooled inside due to a snap tie at the base. This shows why it’s critical to waterproof these spots when building a home to prevent water intrusion.
Use a tool to create a one-inch cant or bevel on the joint, running it up the wall for better protection.
Fixing Honeycombs and Rough Spots
Go through and fill any honeycombs — small holes in the concrete — dime-sized or larger with caulking. We used Tremco Dymonic 100, a polyurethane sealant ideal for movable joints applied around the perimeter of the footing.
Cleaning and Preparing the Surface
Before applying sealant, we used a cup wheel on a grinder to clean rough spots and prepare the surface for caulking. Snap ties were caulked thoroughly, and the cold joint at the bottom of the wall was sealed to block water entry.
Installing the Termination Bar
A termination bar with pre-drilled holes will hold the protectant board in place and prevent rusting below grade. This aluminum bar is secured to the wall with Tapcons and anchors the drain board, which we’ll cover in another video.
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Sealing Pipe Penetrations
For sewer cleanouts and other penetrations, pipes were sleeved and grouted solidly with rapid-set mortar for a secure fit.
We applied Tremco Dymonic 100 sealant around these pipes, ensuring they were fully waterproofed and wouldn’t move. Pipes were spaced two inches apart to allow sealant to be tooled between them for complete coverage.
Applying TREMproof 250GC
TREMproof 250GC, a roll-applied waterproofing product, was applied over the Dymonic 100 sealant to create a durable barrier. This product is used at 60 mils thickness and back-rolled to ensure divots and small holes are fully covered.
Adding Drainage Systems
We installed a J-Drain system at the footing to guide water away from the foundation into a four-inch pipe. The pipe connects to a leach field, which handles foundation drainage and runoff from the gutters.
Chamfering Corners
Corners were chamfered to a three-quarter inch radius, ensuring waterproofing material adhered properly around these critical areas.
Final Inspection
During the inspection, check for efflorescence or other signs of water intrusion to ensure the waterproofing was done correctly.
Wrapping Up
Proper waterproofing of stem walls protects your home from moisture damage. If you’re building or buying, ensure this critical step is done correctly. For help in creating a home, request a project consultation with us. Take a look at our comprehensive collection of similar videos on our YouTube channel, The Real Property Show.
