What is Drain Tile?
Chances are, if your home has a basement and has experienced flooding, someone has told you to get drain tile. But what is drain tile and how does it help?
Essentially drain tile is a way to protect your home from groundwater flooding. It redirects water away from your home before it can enter and cause damage. It is one of those things you never need – until you do! Increased run off from urban expansion and more frequent severe weather systems make our homes more likely to flood. Investing in a drain tile system could save you from lengthy insurance claims and expensive cleanups in the future.
How Drain Tile Works
Despite its name, drain tile is actually not tile at all. When used in the construction industry it actually refers to drainage piping. Drain tile is a system of subterranean drainage laid around the footings of a building. Water always chooses the path of least resistance so drain tile offers the easiest path. The pipe used for drain tile is porous so water finds its way into the pipe system rather than your home. Water is then directed away from your home using gravity or an electric sump pump. Once in the pipe the system directs the water to a dry well or releases it above ground to run off into a storm drain or sewage system.
The Origins of Drain Tile
The practice of using drain tile has existed in agriculture for over 2000 years. Early civilizations used channels lined with clay tiles to divert excess water away from crops. This improved crop growth and yielded better harvests.
However, it wasn’t until 1838 that this drainage system was introduced to America. A Scottish immigrant named John Johnson was the first to deploy the drain tile method on his New York farm. The results were astounding. His crop production surpassed all neighboring properties and drew considerable attention.
One man who was particularly interested was fellow agriculturalist, Henry French. While Johnson pioneered the use of drain tile it was French that brought the idea to the masses. In 1859 Henry French wrote a book titled “Farm Drainage: The Principles, Processes, and Effects”. Following its release the use of drain tile increased to the point that the system became known as French Drain. This term is still commonly used in agriculture today.
Outside of agriculture, drain tile is the term predominantly used. There are other terms that are also used and are inter-changeable with the term drain tile. These include: perimeter drain, perforated drain, foundation drain, rubble drain, weeping tile and footing tile.
Drain Tile in the Construction Industry
The aim of drain tile in the construction industry is to prevent ground water damage to a building. Drain tile gathers water from around a building and removes it before the water can cause any damage.
There are two different types of drain tile system- internal and external. An internal system is when we lay the drain tile on the inside of a buildings foundations beneath the floor slab. This is the more common option when retro-fitting drain tile. It is also used in new builds along with external drain tile.
An external drain tile system is when we lay pipe around the perimeter of a building below the level of the floor slab. This is the preferred method for all new builds, either with or without internal drain tile. It is also possible to retro-fit external drain tile.
If you live in a recently constructed property you may already have drain tile installed. Building regulations nationwide now mandate the installation of drain tile whenever a home has a crawl-space or basement. The only exception to this rule is if the home is being built on naturally well draining soil such as sand-gravel.
Well draining soil lessens the risk of future water damage but doesn’t prevent it. Installing drain tile is still advisable. The benefits far outweigh the initial installation cost and may also make future resale easier. Likewise, when purchasing your next home, especially an older home, ask if there is a drain tile system.
Types of Drain Tile Pipe
There are 2 different types of pipes used for drain tile. The first is rigid PVC pipe. At first glance it resembles ordinary drain pipe but one side of the pipe has small holes to allow water to enter. When laying the pipe the holes we place the holes face down so as water enters the pipe as it rises. As with all rigid PVC pipe, you require corner fittings to change pipe direction. Rigid pipe comes in lengths of 10-feet and costs approximately $8.95 per length. The benefit of rigid pipe is its strength. Manufacturers claim it is crush resistant up to 3000 pounds, so it is unlikely to break during trench backfill. We have seen an average car weighing over 2800 pounds drive over them in a shallow ditch, cracking the rigid PVC pipe. You be the judge.
The alternative to rigid pipe is corrugated flexible pipe. This pipe has small slits on all sides of the pipe. This allows water to enter from any direction, but sand, grit and soil particles are blocked. One recommendation to further protect the pipe from a possible blockage a fabric sleeve can be used along with the pipe. We don’t recommend it. Filters are designed to be changed. They eventually get clogged. You will not be able to change the filter unless you dig up the drainage system. The pipe costs approximately $0.89/foot. It is cheaper than the rigid pipe and doesn’t need corner fittings because it is flexible. The pipe’s polyvinyl composition makes it super durable in high temperatures and cold. It will not crack like the PVC pipe when a 2800+ pound car drives over it.
Regardless of the type of pipe used it will usually be 4 inch in diameter. This is the industry standard for residential drainage, but other diameters are available up to a maximum of 18 inches.
Laying Exterior Drain Tile
Drain Tile can be retro-fitted for an older home, both internally and externally, but installation during the build phase is best. It is ideal to lay drain tile in conjunction with the foundation footing of a new home. This gives maximum flexibility with system design and keeps cost to a minimum.
When a building’s foundation is near completion a 5-6 inch deep trench is dug alongside the footings on the exterior of the house. Installers place the pipe in the trench and then cover it with washed gravel. It is important the gravel is at least 3/4 inch in size to avoid blockages and render the drain tile ineffective. The gravel is then covered with a layer of porous fabric such as landscape matting. The fabric allows water through but prevents soil from clogging up the drainage channel or the pipe. After the fabric is in place it is covered in soil and brought to ground level.
Retro-fitting Drain Tile: Exterior or Interior
Although easier to install during construction, it is possible to retro-fit exterior drain tile. The process is disruptive and costly but often resolves an ongoing water problem.
This method involves digging a drainage trench around the outside of the building at the foundation level with large backhoe truck. It is a labor-intensive process and causes considerable external upheaval. To gain access to the foundations, it may be necessary to remove features such as pathways, decking and trees. External installation takes a considerable amount of time, money, risk to structure, and short-term results with no long-term solution. Contractors will rarely offer a guarantee for over 10-years. Longer guarantees mean they have more confidence in their work.
The alternative is to use the internal method. This is method causes internal disruption but is the most common method for a retro-fit. Prior to installation the basement area needs as empty as possible. That includes removal of floor covering along the walls, and any fixed cabinets. Unfinished basements don’t require much disruption. Once clear, a channel and sump-pit will be cut into the concrete foundation slab. This is a time-consuming and noisy process. Pipe is then laid in the cut channel and will direct any ground water into the sump pit. The electrical pump then pumps the water away. This is a very effective solution for older homes that were not built with foundation drainage.
As previously mentioned, the purpose of drain tile is to direct water away from a building. Where and how we channel water depends on your geographic location. If you live on a property with a significant slope gravity is the perfect way to drain the water away. A slope of 1/4 inch per foot is the absolute minimum to consider for this method. Anything less will be ineffective and possibly result in additional water damage problems. The slope method is a low cost, highly efficient way to remove water.
If the gradient on your property is insufficient you will need to use the collection method. This time the water collects in a sump pit in the basement of the property. From here an electric pump will pump the water away from the property. The final destination can be a storm drain, sewer system or even a dry well. When using a dry well it is important to place it at a significant distance to the property. This will prevent water seeping back to the property and cycling back through the system.
Exterior Drain Tile Drainage Issues
Even if you have drain tile installed around the exterior of your home water issues can still occur. As with other drainage pipes, drain tile is susceptible to blockages. This may be due to tree roots or dirt and debris entering the pipe. Other causes include cracked pipe allowing water to flow back to the building or a malfunctioning sump pump.
Possible signs of a problem include:
- Water stains on the walls of your basement.
- Water pooling in the basement.
- Salt like residue on basement walls (efflorescence).
- Puddles of water around the perimeter of your home.
If you are experiencing any of these issues and cannot find an obvious explanation such as a blocked downspout, then contact a professional to investigate. Finding the source of the problem can be difficult and time-consuming but the longer you leave it the bigger the problem will become.
Drain Tile Cost
The cost of installing drain tile can vary considerably. There are many factors that affect the overall cost. Professional or DIY installation, new build or retro fit, internal or external installation, rigid or flexible pipe etc.
The most expensive option is to hire a professional. It does cost more but you are paying for their expertise and experience. A professional installation will be quicker and less likely to experience future problems. To install an outdoor drain tile at the new build phase you can expect to pay anywhere between $50 and $80 a foot. The larger the drain the higher the cost. A good average to work with for budgeting is $70 per foot. This is at the higher end but should give a realistic figure for you to work with. That would mean you need to budget $3,500 for 50 foot of drain tile. This cost will increase considerably if the trench is for retro-fitting drain tile in an older home.
DIY is always a cheaper alternative as you make a considerable saving on labor costs. There will still be material costs and equipment hire. Daily hire of a trencher is roughly $400 and a compacter about half of that. The DIY option will probably take longer but you can complete the work in sections.
If you have exhausted all the alternatives and are retro-fitting internal drain tile the costs are higher. You will need to budget up to $4500 when using the “pitched” method and up to $15,000 if using an electric sump pump. Basement access, size and project complexity all impact the installation cost.
Both internal and external drain tile drain the excess water away from your home. If the water can drain to an existing external drainage system your additional costs will be minimal. However, if the water is draining to another area on your property you may need to install a dry well. There are several types of dry well on the market, made from a variety of materials. The volume of water It needs to handle will dictate the type and size of dry well you will require. A professional may charge up to $5000 for installation. The most you would expect to pay for materials and self-installation is approximately $500.
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