Fixing your block foundation may involve more than just waterproofing!

When the mortar joints between concrete blocks crack and when the concrete blocks themselves crack your foundation wall is vulnerable to water penetration and consequently, basement leaks. When dealing with basement leaks associated with concrete block foundations, waterproofing may not be the only type of foundation repair required. When there is evidence of concrete block / cinderblock movement, foundation wall stabilization (or reinforcement), should receive serious consideration. The most typical symptoms of structural issues associated with block walls are visible horizontal cracking (usually visible only from inside the basement) and step cracking in the mortar joints between the concrete blocks.

Horizontal cracking in block walls is caused by the soil outside pushing the wall in at grade height

Horizontal cracking below top course of block

Step cracking in cinderblock foundation wall

Step cracking in block foundations is due to settlement


In the picture above, the horizontal cracking in the mortar joint immediately below the top course of blocks is plainly visible. This horizontal cracking typically occurs at grade (the height of the soil outside) and results from the force of soil pressure applied to the foundation. This tends to occur as a foundation ages because the mortar joints weaken from the cyclical pressure applied against the foundation by the expanding and contracting soil outside.

Soil pressure applied to the foundation wall can cause the wall to move inwards and tip at approximately grade height

Because changing soil pressure on a weakened concrete block foundation wall can ultimately lead to structural failure over the course of many years, relatively simple reinforcement systems have been developed to arrest foundation movement exemplified by horizontal cracking, step cracking and bowing of the block wall towards the interior of the basement. One such reinforcement system involves the use of carbon fibre reinforcing straps. The following illustration shows the typical installation of the carbon fibre reinforcing straps used to stabilize a concrete block / cinderblock wall.

The installation of carbon kevlar reinforcing straps makes the foundation 3 times stronger than without them so the wall will no longer yield to soil pressure

For more details on the concrete block wall reinforcement system that we recommend and install, click on the brochure image below.

strap brochure View Brochure
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The next image is a completed perimeter drain installation system that included the installation of carbon fibre reinforcing straps. The installed reinforcing straps will prevent the foundation wall from moving inwards when pressure is applied against the wall by the soil outside.

Installing carbon kevlar reinforcing straps will prevent foundation walls from bowing

How a cracked block foundation is reinforced

The first step involved in the installation of a carbon fibre reinforcing strap is grinding of the wall surface onto which the reinforcing strap will be installed. This wall grinding is done to ensure excellent adhesion of the subsequently applied epoxy to the wall, as well as to ensure that the foundation wall surface is as flat as possible.

Wall grinding will generate a tremendous amount of dust; therefore it is crucial that the waterproofing contractor use a negative air machine or air scrubber to minimize the amount of dust within the work area, and the home in general.

Wall grinding is the 1st step undertaken to prepare for the adhesion of epoxy   Wall grinding produces significant dust which must be controlled by using an air scrubber

The image below clearly shows the ground area of the block foundation wall onto which the carbon fiber reinforcing strap will be installed.

The wall grinding is complete and now the wall is ready for the application of epoxy

After grinding the wall, the dust is brushed off the wall and epoxy is applied onto the wall surface. The area over which the epoxy will be applied corresponds to the width and length of the carbon fiber strap that will be installed.

The application of epoxy on the ground block wall

The epoxy on the wall is then spread evenly over the wall surface.

After the application of epoxy to the foundation wall, the epoxy of spread over the surface on which the reinforcing strap will be installed

Below is an image showing the prepared substrate onto which the reinforcing strap will be installed. Carbon fiber reinforcing straps are typically 6.5' long.

The epoxy has now been spread over the area onto which the reinforcing strap will be installed

The reinforcing strap (also referred to as a carbon fiber/Kevlar™ grid system) is unique in that it is currently the only pre-cured product that is fully encapsulated in epoxy.

The epoxy will bind the strap to the wall by effectively creating rivets attributable to the strap design

By encapsulating the carbon Kevlar™ grid in epoxy, every hole in the grid allows the epoxy applied to the surface of the grid to come into contact with the epoxy previously applied to the wall; as a result, epoxy rivets are formed. These rivets act as rip stops which prevent the grid (or reinforcing strap) from peeling off the foundation wall. The image below shows a fully epoxy encapsulated reinforcing strap.

The carbon fiber strap is now fully impregnated with epoxy and is ready to cure.

In the image below you can see 3 installed carbon Kevlar™ reinforcing straps at the recommended spacing of 4' apart. Once the epoxy has fully cured, the cracked or moving foundation will be permanently repaired as the wall is now 3 times stronger than it was originally.

View of straps installed at 4 foot intervals

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