Perimeter Drain Pipes can Significantly Impact Your Home

Here in Victoria with our rainy winters, we have been building houses with perimeter drainage for many decades. 
Today we build houses with 2 sets of drainage systems (to handle roof rain water and underground water levels), to ensure water flows away from the house, not into it. Hydrostatic pressure from underground streams etc. and steep grades sloping toward the building, especially where rock is involved, can circumvent even the best drainage system. In most circumstances though, proper functioning perimeter drains and damp proofing should keep your building dry.

All perimeter drains will collect dirt and debris over time especially with open gutters. We suggest homeowners should have drains cleaned every 5 years or so and if you have a lot of tree litter, you should install gutter covers and downspout leaf catchers to help keep drains clean and functioning properly. Often drains will operate even with some obstruction from debris, but will not be able to keep up with a heavy downpour, causing water levels to rise, possibly flooding the home or basement/crawlspace area.

The other problem caused by malfunctioning perimeter drains, beside moisture incursion, is erosion of the soil underneath the footings. When the footings are undermined because of bad drainage, with no soil to sit on, of course they sink and settle usually cracking the walls and in some cases causing floors to slope. I have even seen windows cracked due to house settling. There are other reasons for foundation settling but perimeter drains are often the culprit. When we see old houses with nice new shiny white perimeter drains under the downspouts, we always suspect there has been a previous problem. Most home owners ignore the drains until there is a problem.

Todays drains are typically made with a white PVC 4″ pipe and usually several clean outs can be seen with caps, sticking out of the ground. Older drains in the Victoria area were made out of 2′ sections of either clay or concrete, or in the 90’s, out of BIG ‘O” corrigated black plastic piping. All of these types of drains get plugged over time and are often subjected to root damage etc. Some houses, even very old ones, never experience any problems despite poorly functioning drains while others seem to have topography and soil conditions that invite trouble. Having perimeter drains replaced is a very expensive proposition, especially if there are substantial concrete sidewalks and driveways near the house perimeter. In some cases its cheaper to install the drains inside the house. Often however, a simple cleaning or spot repair can vastly improve the situation. Some companies are advertising pulling new drain material through the old piping, to form a new drain system without digging up the ground around the house. If a basement redo or suite is contemplated, always make sure to get the drains checked before installing expensive flooring and trim.

Service Contractor Links      DrainMaster    Drain Pro     Island Basement Systems

Note: Fleetwood Building Inspections does not recommend nor endorse these or any other contractors but offers these links as a sampling of services available in the Victoria area.
(click on pictures to enlarge)


Moisture leaking through the concrete leaves a spiderweb of white cracks


Old concrete drainage tile is likely plugged


Moisture and efflorescence is usually a sure sign of poor perimeter drainage and lack of a vapour barrier under the concrete


Foundation wall cracks caused by non-functioning perimeter drains


Water build-up and efflorescence in crawl space from poor drainage



Two sets of drains are typically installed in new housing


Sometimes its cheaper and easier to install inside perimeter drainage


Big ‘O’ drainage pipe from the 80’s tend to clog up with the corrigation design







Information provided by Fleetwood Building Inspections