Drainage Tile

Clay Tiles Solid State Inspections

Water is one of the natural enemies of our homes and it will follow the path of least resistance while flowing with gravity. If the path of least resistance leads to your homes basement, flooding is usually the end result. One of the best defenses against water entering our homes is the use of a drainage system, often called drainage tiles, to carry excess water safely away.

What is Drainage Tile?

Plastic Drainage Pipe

Closeup of Big O (ABS) Drainage Piping. Look closely and you can see perforations for water to penetrate.

The term drainage tile originated from the actual use of round hollow clay tiles that would be buried under the perimeter of the home. The tiles would be laid with a small gap between them which would allow water in the soil to penetrate into the piping and flow with gravity away from the home. More modern products follow the same principle but include various perforated plastic piping materials such as PVC and ABS. Drainage tile systems may also be called footing drains or perimeter drainage.

Drain piping is most commonly installed around the outside of the home but in some homes, particularly where drainage was added after original construction, the drains may be on the inside of the foundation wall.

What Makes Up The Full Perimeter Drainage System?

The piping material is only a part of the whole perimeter drainage system. Ideally, the drain piping is placed along side the lowest portion of the homes foundation wall around the entire home with a slight slope for gravity to drain the water away from the building. It is then covered with a layer of gravel to help prevent the pipe from plugging with debris and to make it easier for water to find the pipe perforations. Then the whole system is covered with a filter cloth to keep out small dirt and top soil is added to the level of the property.

The drainage water flows by gravity to a sump pit. Ideally, the sump pit is then connected by gravity to the municipal storm sewer. In rural areas, it is common for the water to discharge into a ditch which then flows away from the property. If the sump pit is below the level of the storm sewer, it may be necessary to have a sump pump assisting gravity by pumping the water high enough to flow away from the home. Sump pumps need electricity to operate which does increase the risk of flooding in a power outage.

Should Roof Gutters and Downspouts Connect to the Drainage?

Some builders including Mike Holmes believe adding roof water to the drainage system is asking for trouble as concentrated water alongside the foundation or potential blockages increase the risk of wet basements. He typically recommends directing roof drainage onto the property. While that may be wise in Ontario, on the West coast of Canada we see so much rain that asking the water saturated property to also handle the roof drainage may cause site erosion from surface water flows. Properly designed and installed drainage systems on the west coast can support drainage from the roof water and in some municipalities it is required to prevent surface erosion into the municipal systems.

What is the Life Span of Drainage Systems?

Properly installed drainage systems should last the life of the building however this life span can be shortened by premature failure. Tile pipe drain systems are prone to collapse under weight or mechanical damage which could include original installation mistakes, shifting and settling soil, or the weight of heavy vehicles in shallow areas. Tree roots like to seek out the moisture in drainage systems blocking drainage and breaking pipes. It is also possible for pipes to become clogged from debris and soil carried in by water flow. Regular maintenance of your drains and sump pit can help keep drainage pipes flowing freely and help them last the life of your building.

How Can I Tell if My Drainage System Has Failed?

Depending on the slope of your property and the amount of perimiter drainage needed, it can be very difficult to determine if your drainage system has failed. If your property is heavily reliant on the drainage system, a failure could appear dramatically in the form of a wet basement or flooding on the exterior of the home. If you are suspicious of a failure in the drainage tile, call in an expert to ‘scope’ the tile to ensure it is functioning properly before more damage may occure.

What do Home Inspectors Look For with Drainage Tile?

Unfortunately, drainage systems are underground and not readily visible in a home inspection. Occasionally when there is a failure in the system, there may be clues a home inspector can see of this failure and they will recommend further analysis by a drainage contractor. It is particularly difficult to determine in dry weather if the drainage system is functioning correctly.

Final Thoughts

Our basements are like inside out swimming pools where we want to keep water on the outside and stay dry on the inside. Correctly functioning drainage systems will help the foundation walls drain water safely away before it has a chance to penetrate into our homes. If you have water penetrating into your basement or crawlspace, it is important to have a professional drainage and foundation expert investigate immediately to prevent more damage.

By James Bell - Owner/Operator of Solid State Inspections Inc.