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How to Install a Basement Sump

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How to Install a Basement Sump

In older homes that were built without adequate basement waterproofing systems, a sump and pump is a relatively easy way to reduce or even eliminate wet basement problems.


First, you will need to select a location for the sump. You will want to place the sump near a wall in the basement, since the sump pump discharge will need to exit the basement and travel at least 10 feet outside to discharge. Pick a location that will be easy to work in, and where you can punch a hole through a rim joist to reach outside, but stay at least 8" away from the foundation wall, to avoid hitting any footings.
Once you have selected the location for the sump, you will need to trace the outline of the sump liner on the floor. Leave a 3-4 inch gap around the liner to make it easier to fit the liner in the hole (you will fill in the gap with gravel and concrete later).

The next step is the hardest, namely the removal of the concrete floor. It is relatively quick work with an electric jackhammer, if you can rent one. If you can't rent one, you can make do with a hammer drill and a masonry bit, a sledgehammer, and a masonry chisel. Using the largest masonry drill bit you can chuck in the drill, begin making holes every few inches in the concrete along the outside perimeter, then use the hammer and chisel to crack the concrete between the holes. Continue drilling holes and hammering the concrete until you can remove it in chunks. If your floor has reinforcing steel mesh installed in it, you may need a pair of heavy wire cutters or a metal grinder to cut it.

Once all of the concrete has been removed from the opening, you can begin to make the sump hole. You will want to dig the sump hole at least 12" deeper than the sump liner. Use 5-gallon buckets to cart the debris outside.

Once your hole is ready, begin by placing coarse gravel in the bottom of the hole, so that the sump liner sits flush with the basement floor when placed in the hole. This gravel will promote good drainage, and help water move into the sump where it can be pumped away (instead of moving into your basement at another spot). Depending on the liner used, you may have to drill numerous holes in the sump liner to allow water to enter so the pump can pump it away. The drilled holes should be smaller in diameter than the size of gravel used so that gravel does not come through.

Once you have seated the liner in the hole, place gravel around the sides of the sump liner, coming up to about 6" below floor level.

Mix your concrete, and pour a 6 inch layer of concrete over the gravel, filling in the floor up to the edge of the sump liner. Be sure to mix the concrete according to directions, and use a trowel to achieve a smooth surface. After the concrete has set up reasonably well (at least 8 hours), you may resume working on the sump.

Now you will need to install the sump pump plumbing. Most pumps use 1.5" PVC pipe, but review the instructions that came with your pump to be sure. Assemble the PVC piping from the sump pump outlet up through your home's rim joist, and to the outside. Leave a short stub of PVC pipe on the outside, you can attach a flexible hose to go the rest of the way.

When assembling the piping, be sure to dry-fit the entire section before gluing anything. Work in a well ventilated space, to minimize exposure to the solvent fumes.
Use a hole saw with the appropriate sized bit to cut a hole through your siding and rim joist.

Place the pump in the liner, attach the final section of pipe, and plug your pump in. It may be necessary to drill numerous holes in the liner to enable water to get in to be pumped out. The diameter of the drilled holes must be smaller than the size of the gravel used so that no gravel can enter the sump liner.

Pumps come with different types of floats. For any type of float it is important to ensure that the float on the pump is unobstructed so that it can rise and fall with the water level in the sump. As water flows into the sump the float needs to be able to rise to a level that will activate the pump switch. Then as the water is pumped out, the float needs to be able to fall back down without getting stuck between the pump and the sump liner wall. Usually it is a simple matter of just centering the pump in the sump liner, but it is best to double check your set up.


Consider adding a battery backup to your sump pump. If you lose power during a heavy rainstorm (when your pump is likely to be activated), you could end up with a wet basement.
Local codes may require a one-way valve to be installed in your plumbing, so that water cannot enter the sump through the plumbing from the outside.
Be sure and read over the instructions that came with your sump pump carefully.

Always wear eye protection!
Use hearing and dust protection during concrete cutting
Wear gloves when mixing and handling concrete

Things You'll Need
Electric mini-jackhammer
5 gallon buckets for excavating
Plastic sump liner
4-8 cubic feet of coarse gravel
1 bag ready mix concrete
Mixing tub for concrete
PVC piping (diameter depends on the pump used)
submersible sump pump