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 or 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

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What is an interior weeping tile system?

An interior weeping tile system, also referred to as an internal perimeter drain system, is internal waterproofing that is the alternative to foundation excavation and waterproofing usually for a concrete block foundation.

Compared to exterior waterproofing, an interior weeping tile system is much less expensive (since no excavation is involved) and is a proven, highly effective basement waterproofing method. Interior perimeter drainage systems are used mainly for waterproofing concrete block / cinder block foundation walls. This waterproofing system is so reliable that some very large companies sell this type of system for dealing with virtually all foundation waterproofing problems. Internal waterproofing is often the approach of choice given the destructiveness of foundation excavation.


Interested in information about conventional exterior weeping tile installation? Click to read about weeping tile systems.

A perimeter drainage system keeps a basement dry by providing drainage for water that flows into and pools within concrete block / cinder block foundation walls. 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 in many ways similar to the weeping tile system that is installed along the footing on the exterior, at the base of your foundation.

Interior perimeter drain system
Interior weeping tile system installed next to the footing draining into sump pump liner

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This basement waterproofing system involves installing a drainage system on the perimeter of the inside of the basement, beneath the basement floor, therefore, no digging outside the home is required. An installed interior perimeter weeping tile system drains water at the footing of the foundation in much the same way as exterior weeping tile. An interior weeping tile system allows water, which has pooled in a concrete block / cinder block foundation, to drain, thus preventing water from leaking or seeping from the concrete blocks onto, or beneath, the basement floor. By draining the cinderblocks and evacuating the ground water, the interior weeping tile system helps to extend the useful life of the concrete block foundation which does deteriorate over time due to the saturation of the blocks from pooled water within them. 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:


If you are wondering if this waterproofing method is economical, be sure to read our blog post: Interior basement perimeter drain systems - A low cost alternative

Wondering what a system like this would cost? Check out the article: The average cost of basement waterproofing

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, next to the foundation walls is jackhammered open in order to expose the footing and to excavate a trench for the installation of drain pipe / drain tile;

Jackhammering trench    Exposed footing clearing debris

2. The fully exposed bottom course of concrete blocks have weeping holes drilled into the hollow cavities within the blocks;

Water pouring out of weeping hole drilled into a concrete block Installed drain pipe with drilled weeping holes in bottom course of concrete blocks

3. A perforated drain pipe is installed next to the footing;

Drain pipe installed beneath basement floor to channel water to sump liner Perimeter drain pipe is installed along footing to collect water from weeping holes in concrete/cinder blocks

4. An air gap membrane is installed along the wall;

Air-gap membrane installation in progress Air-gap membrane wrapped over drain pipe to ensure water can drain over the footing to the drain pipe

5. In the absence of a suitable sump pump liner, a sump liner and submersible sump pump are installed beneath the floor, with the liner cover installed flush with the floor;

First stage of sump pump liner installation

6. The drain pipe is routed to the sump liner, beneath the basement floor 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

Perimeter drain pipes are connected to sump liner into which the water drains Submersible sump pump installed at bottom of sump liner

Click to learn more about sump pumps

7. The drain pipe and lower portion 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.

Perimeter new concrete installation 

Concrete repair of trenching along the foundation wall

 Sump pump discharge pipe is routed to drain water above the foundation to the outside of the home

Sump pump discharge pipe installation

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How water enters and pools within a concrete block foundation:

How water leaks through a concrete block foundation

Illustrated steps involved in installing an interior weeping tile system:

Concrete block foundation de-watering - Step 1: Trenching Concrete block foundation de-watering - Step 2: Weeping hole and drain pipe installation
Concrete block foundation de-watering - Step 3: Air gap membrane installation and concrete re-pour Submersible sump pump installed as part of an internal de-watering system

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 the 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).

Sump pump and discharge installation

Unsightly discharge pipe installation (client wanted minimal drywall damage)

Discrete discharge installation allows the discharge pipe to be concealed behind a finished wall

Instead of bringing the discharge pipe out through the cover the pipe goes through the sump liner

A discrete discharge allows you to conceal the discharge pipe behind a finished wall

A discharge pipe installed against the wall allows the pipe to be concealed behind finished basement walls

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