Home Drain Tile: What Is It For?

Drainage Pipe

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Excess water around the base of a home’s foundation creates many problems, ranging from basement leakage to more serious issues like foundation subsidence and cracking.

These problems can snowball and affect the rest of the house. One of the most effective ways to combat excess water is by creating a drainage system around your house called drain tile.

What Is a Drain Tile System?

Home drain tile refers to a drainage system around the perimeter of a home, either outside or inside. Drainage is accomplished with a series of long perforated tubes laid deep in the earth right next to the home's foundation.

Drain tile is an antiquated term, though it's still widely used today. The material is not the same as the tile used for flooring in homes. In the early years, drain tile, mainly for agricultural applications, was made from fired clay formed into an inverted horseshoe shape or a cylindrical pipe shape.

Today, drain tile is made of either rigid or flexible plastic. The plastic is perforated to allow the water to pass inside the pipe. Gravel is laid on top of the pipe.

How Drain Tile Works

Water that builds up around the base of a home’s foundation can create hydrostatic pressure and this can leak into the home or damage the foundation. 

The best-case scenario is for water at ground-level to remain at ground-level and to move away from the house. If water does happen to percolate downward and reach the foundation, it should be kept moving so that it does not build up.

The drain tile pipes are laid at the base, or footing, of the foundation. Crushed rock or gravel extending at least 12 inches outward and 6 inches upward—a volume specified by code—is laid on top of the pipe.

The rock or gravel equalizes the weight of the soil above and it acts as a perforated pass-through for the water to reach the pipe. Plus, the rock itself aids with the lateral movement of the water.

Water fills the pipe through the pipe’s perforations. Fabric laid over or wrapped around the pipe protects the pipe from filling with silt. Water moves downslope through the pipe and away from the house. The water terminates either at a sump pump, where it is pumped away from the house, or to daylight.

Definition

Daylight refers to a drainage termination point where a pipe is extending from the ground, usually from a hill or slope. 

Drain Tile Use in Homes

When creating a home water management system, it’s best to think in terms of concentric circles. Stopping water at the widest circle is always best—you want to keep it as far away from the house as possible.

The next-closest circle is the drain tile around the home’s exterior foundation. When those methods are not possible, you’ll need to move the drain tile inside the house, in the basement.

With this, sections of the basement’s concrete slab are broken up with jackhammers and removed. While the drain tile can be installed in the slab, it’s best to locate it below the slab. The floor is then replaced.

While this is a highly disruptive process, installing the drain tile inside the house offers the advantage of creating a system that typically does not clog up.

Types of Drain Tile Pipes

Rigid Pipe

Rigid PVC pipe in 10-foot sections that have holes on one side are laid with the holes downward. The PVC either has built-in bell-mouth ends to allow for pipes to connect end-to-end or separate couplings. Water enters the holes from the bottom and then makes its way to the termination point.

Flexible Pipe

Corrugated flexible plastic pipe comes in long coils, typically 50 feet long. This pipe is laid at the foundation footer. A fabric membrane, also known as a sock, is wrapped around the pipe. Sometimes, the pipe comes with a pre-attached sock. Water enters the pipe through slits and is moved downslope away from the house.

Code Requirements For Home Drain Tile

Your community may require a drain tile system around your home if lower-grade spaces in the house are habitable. There may be exclusions if your house is on well-drained ground or on sand-gravel mixture soils. IRC R405, which many communities adopt, states

Drainage tiles, gravel or crushed stone drains, perforated pipe or other approved systems or materials shall be installed at or below the area to be protected and shall discharge by gravity or mechanical means into an approved drainage system.

Code does allow for the fabric membrane to be laid on top of the gravel rather than being wrapped around the pipe.

It is always best to consult with an expert when considering if drain tile installation is required or beneficial.