Renovation & Design

Plastic pipe likely drain for window well


This plastic pipe near a basement window is likely a drain for a future window well.

Question: We have a PVC pipe sticking out of the ground beside our house, underneath a basement window, which appears to go down about six feet. What function does this serve?

Bruno Klassen

Answer: The unusual looking pipe under your basement window is likely a drain pipe for a window well. This may not provide any useful purpose unless you install the window well to protect your basement window.

The purpose of this pipe is to provide fairly clear drainage of excessive water, which could accumulate inside a window well during a heavy rainstorm.

This pipe likely does go down about as far as you assume and it should terminate just above the weeping tile. The top of the pipe is likely visible due to erosion of soil, or if it was left slightly higher than grade to allow easy identification.

Since your window is an older, wooden variety, it is likely this drain pipe is not original to the home. It was probably installed at the time of a foundation repair.

This repair may have been just for the area near the window, or may have been for the entire foundation wall on that side of your home. Digging the soil down a bit outside the foundation in that area may reveal a waterproofing membrane, foam insulation, or other evidence of the repair.

If you see this evidence, digging a few inspection holes further down the wall may help determine how extensive the repair has been.

If there is evidence that the repair is on the entire foundation wall, or more than one wall, it is likely that the entire exterior portion of the weeping tile has been upgraded. That is a major part of any good foundation repair and will prevent excessive accumulation of moisture in the soil outside the foundation. This moisture, from rain and melting snow, should easily be channelled through the new perforated plastic drain piping to the catch basin in the basement. This water will then be harmlessly drained in to the municipal sewer system, keeping your basement nice and dry.

To ensure this is working as designed, lift up the grate or cover of your basement floor drain during rainy weather. You should see water dripping from the openings in the sides of the catch basin, which are the ends of the weeping tile installed under your basement floor slab.

These should be connected to the new plastic drain piping outside the foundation and act as crude pipes to direct the water to the catch basin.

The plastic pipe you see sticking just above the ground should either be connected directly to the outside drain piping well below grade, or terminate just above it.

If you don’t see much water dripping from the terminal ends in the catch basin during heavy rain, or during the spring thaw, then something in the system is blocked or damaged. Calling in a rooter technician, or plumber, with a camera to scope the under-slab tile will be the next step.

The unusual thing about the pipe in your yard is that it has been installed for draining a window well that does not exist. For this to have any function at all, I would purchase the appropriate size window well, at a local home centre or landscaping supply retailer, and install it. This will require digging down under and around your basement window, large enough to install the galvanized metal well.

Once enough soil has been cleared, the unit should be placed inside the hole. It should extend high enough above the bottom of the window frame or buck to prevent soil from topping it. But, it should not be too high to prevent easy access to clean or remove the window sash, if needed. Ideally, it should extend out far enough to allow a person to escape the basement window in case of fire, unless there is another means of egress in the basement.

Once in place, the window well should be bolted to the foundation wall. This can be done with various types of fasteners designed for this purpose. The simplest method may be to buy about four drive-in anchors bolts with removable nuts. The first step for installation is to drill the holes in the window well flange slightly larger than the anchors.

Next, mount the well in place and drill holes through the openings into the foundation concrete with a masonry bit and drill. Once the holes are deep enough, drive the bolts into the foundation wall. After ensuring the window well is properly positioned, install and tighten the washers and nuts to hold the metal well securely in place.

Once the new window well is secured, the top of the PVC pipe may have to be trimmed to allow proper drainage. The bottom of the well should be filled with clean, crushed limestone to a depth about four to eight inches below the bottom of the window frame. This will ensure any small accumulation of water will not leak into or damage the basement window.

The PVC drain pipe should be shortened so that the top is just covered with the new drainage stone. Once complete, the outside of the window well cavity can be filled back in and extra soil added to ensure a good slope away from the foundation, further preventing basement seepage.

The pipe sticking up above the ground outside your basement window should be a functioning drain, to prevent moisture intrusion and damage. It will only work in this manner if you install a proper window well and improve the grading around it.

Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the past president of the Canadian Association of Home & Property Inspectors — Manitoba ( Questions can be emailed to the address below. Ari can be reached at 204-291-5358 or check out his website at


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