How to Build a Wet Wall
To build a new bathroom, half-bath, shower unit, kitchen, or laundry room in your basement, you'll probably have to build a wet wall to enclose the pipes. This sounds like a formidable undertaking, but the work is not complicated, just heavy. In many homes, you will have to break out the concrete to expose the existing drain line. If drain stub ins are already in place, you won't have to remove the concrete.
You can save some money by tearing out the concrete with a sledgehammer (trim the edge neatly with a cold chisel), but you'll find a rented electric jackhammer well worth the expense. Be sure you have an easy way to remove the old concrete—trash bags won't work.
When you install the drain lines, slope them for proper flow; a 1/4-inch drop per foot is standard, but check your local codes. They may require a steeper slope.
You'll need to spend about 2 days to frame and plumb an 8-foot wall. Make sure you're able to measure and mark, break concrete, and install PVC and copper pipe.
What You Need
- Tape measure
- Chalk line
- Small sledgehammer and cold chisel
- Cordless drill
- Electric jackhammer or 12-pound sledgehammer
- Mixing hoe
- Reciprocating saw
- PVC and copper pipe
- Protective plates
- 2x lumber
- PVC primer and cement
- Concrete mix
Step 1: Mark and Remove Floor
Snap chalk lines to mark the areas to remove. Using a sledgehammer and brick set or a circular saw and masonry blade, score the lines. Break out the concrete with an electric jackhammer or sledgehammer. Dig a trench 2 inches deeper than the main drain.
Step 2: Connect to the Main Drain Line
Make a connection to the main drain line. Dry-fit and mark the new drain and vent lines and cut them to fit. Support the new lines with stakes to slope them properly.
Step 3: Install Floor Pipe
Cement the fittings to the pipe with solvent cement, keeping the fitting aligned. Recheck for proper drain slope and place aggregate (such as crushed rock) around the line to hold it in position. After the line passes inspection from your local building department, backfill the trench with soil and concrete. Finish the concrete to match the floor.
Step 4: Frame a Stud Wall
Frame a stud wall to enclose the drain and vent lines. Drill holes in the studs for horizontal pipe runs. Assemble the remaining parts of the drain-waste-vent system. Connect the vent to the main stack.
Step 5: Finish Supply Lines
Install shutoff valves on the supply lines closest to the new wet wall and extend copper supply lines to the wall. Install blocking or straps where necessary so the supply lines are supported properly, and tack protective plates where the lines pass through the studs. Plug the lines to keep construction debris out. Leave the wallcovering off until the building inspector has approved the installation.