There is little more annoying than leaking block foundation walls; fortunately it is possible to fix a wet basement on the inside by installing an interior weeping tile / perimeter drainage system.
On this page:
What is an interior weeping tile system?
The steps involved in installing an interior weeping tile system
How water enters and pools within a concrete block wall
Illustrated steps involved in installing an interior weeping tile system
An interior weeping tile system, also referred to as an internal perimeter drain system, is a method of waterproofing foundation walls from the inside as an alternative to foundation excavation and waterproofing. Interior perimeter drain systems are mostly installed to waterproof leaking concrete block foundations.
Compared to exterior waterproofing, an interior weeping tile system is less expensive (since no excavation is involved) and is a proven, highly effective basement waterproofing method. This waterproofing system is so reliable that some very large companies sell this type of system to deal with just about every wet basement situation. Waterproofing the basement on the inside is often the approach of choice given the destructiveness and cost of foundation excavation.
Interested in information about conventional exterior weeping tile installation? Click to read about weeping tile.
A perimeter drainage system keeps a basement dry by providing drainage for the water that pools within the block foundation walls that subsequently seeps onto the basement floor. This system is also very effective for dealing with a high water table under the basement floor slab, and for any water that leaks through foundation cracks. The interior weeping tile system is a basement waterproofing system that will keep your basement perfectly dry, and is similar to the weeping tile system installed on the exterior, at the base of your foundation.
This basement waterproofing system involves the installation of a drainage system against some or all of the exterior walls of your basement beneath the basement floor; therefore, no digging outside the home is required. The system drains water at the footing of the foundation in much the same way as exterior weeping tile does. An interior weeping tile system allows water, which has pooled in a concrete block / cinder block foundation, to drain behind a membrane on the wall; thus eliminating the risk of water seepage onto the basement floor. By draining the cinderblocks and evacuating any ground water, the interior weeping tile system helps to extend the useful life of the foundation. Properly installed, an interior weeping tile system will keep your basement dry for the life of your home. Here’s what a completed interior perimeter drain system installation looks like:
Steps Involved in Installing an Interior Weeping Tile System
Installation of this perimeter drainage system requires access to bare basement walls inside the home. In finished basements, the lower part or entire stud walls are removed.
Here are the installation steps:
1. The basement floor slab along the foundation walls is jackhammered open in order to expose the footing and to excavate a trench for the installation of drain tile;
2. The fully exposed bottom course of concrete blocks have weeping holes drilled into the hollow cavities within the blocks;
3. A perforated drain pipe is installed next to the footing;
4. An air gap membrane is installed along the wall;
5. In the absence of a suitable sump pump liner, a sump liner and submersible sump pump are installed beneath the floor;
6. The perimeter drain pipe is routed to the sump liner so that the water collected from the draining concrete / cinder blocks can be mechanically evacuated to the exterior by the sump pump. Note: it is illegal in most municipalities in the GTA to dispose of this water by connecting to the floor drain; and
7. The drain pipe and lower part of the drainage membrane are positioned and new concrete is poured over top and levelled. On completion, all that is visible is a scar in the floor along the wall, a membrane fastened to the wall and a sump pump discharge pipe to the exterior.
Below is a typical sump pump installation that is part of the interior weeping tile system.
Note: Instead of having an unsightly discharge pipe emerging from the centre of the sump liner, it is possible to conceal the discharge pipe within your framed basement walls by modifying the configuration of the discharge so that it is “discrete” (beneath the concrete floor and travelling up the wall behind the drywall).