Block foundation repair
Troubleshooting block foundation issues
Understanding your block foundation
At H&N Basement Worx, we delve deep to diagnose and resolve the unique challenges your block foundation may face. We’re here to provide straightforward, practical solutions. With our hands-on, community-first approach, we ensure your foundation stands strong—guaranteeing peace of mind and the security of your home.
Window wells letting water in your basement? Here's why:
Bowed foundation walls
Having a bowed foundation wall is a common problem in the world of foundation repair. In most cases we see this scenario when the exterior side of the foundation has clay soil that is either extremely wet or has been backfilled too high against the foundation.
When there is too much pressure being exerted against the foundation it begins to move inward and develop a gap horizontally along one of the mortar joints (as depicted in the picture to the right) à This is what is referred to as a Bowed Foundation Wall.
You want to catch this problem before the wall bows inwards too far. The rule of thumb is – if a foundation wall has less than 2” of bow you can repair it without the need of pushing the wall back to its original vertical position. If the wall has 2” of bow or more you will need to excavate the exterior side of the wall so it can be pushed back into place. Once there you can use the proper repair method to hold it in place.
So what is the proper repair method to fix this issue? The one we use and recommend to properly reinforce bowed walls so they don’t continue to move inwards is…
Carbon Fiber Reinforcement Straps
The carbon fibre strap is secured to the foundation with a special two part epoxy. We install the carbon fibre wall supports to the inside of the basement so it is less intrusive and less expensive than other repair options. There is no digging into the yard and carbon fibre provides a clean and fast installation.
The typical spacing between straps is 4 feet on centre but in extreme situations that space may decrease based on varying factors such as block size & wall load. The final finish is smooth, flat, and nearly invisible when painted. The repair is maintenance-free and can be covered without taking valuable square footage away from a basement remodel.
Sheared foundation wall
A sheared foundation wall is best described as such – usually found at the first mortar joint from the floor you will notice that the second row of blocks is over hanging the very bottom row of blocks. It can be as little as an 1/8 of an inch to 3 – 4 inches. If you see the shear here or a few blocks up it means the foundation has lost the battle to the heavy soil that sits on the exterior side.
If you are faced with this situation there are a few things that need to happen in order to rectify the issue at hand. First step would be to have a structural engineer inspect the damaged area to see if there are any other issues in the foundation. Once done the engineer will provide the details required to properly repair the issue.
As long as there isn’t too much distortion along the affected length of wall the typical repair process will look like this:
- The exterior side of the foundation can be excavated so there is no longer any load pushing against the wall
- We push the wall back to maximum practical recovery
- Core pins are then installed to lock the bottom of the foundation to the footing
- Carbon fibre straps are installed along the wall to properly reinforce it
- The exterior side of the foundation is waterproofed and new weeping tile is installed
- The wall can then be backfilled once the supports on the inside have properly cured
In some cases the wall may require rebuilding but that will ultimately be determined by the structural engineer.
Pushed in fondation wall
There are times where we inspect a house that did not have the top of the foundation properly anchored to the sill plate. Anchor bolts are a common fastener used to tie the house down to its foundation but if this step is missed and the grade around the house is high you will eventually see the top of the foundation push inwards.
When you come into contact with this situation the fix is similar to that of having a sheared wall provided there arent too many mortar joints disrupted.
- The exterior side of the foundation can be excavated so there is no longer any load pushing against the wall
- We push the wall back to maximum practical recovery
- Carbon fiber straps are installed along the wall and tied into rim joist area
- The exterior side of the foundation is waterproofed and new weeping tile is installed
- The wall can then be backfilled once the supports on the inside have properly cured
In some cases the wall may require rebuilding but that will ultimately be determined by the structural engineer.
Shifted or cracked foundation blocks
Blocks that have shifted and are not sitting flush like the rest of the wall have had some form of pressure pushed against them like that from the roots of trees.
This example shows blocks that have been forced inwards and broken due to this excessive force. The tree root that was outside the wall was over 12” thick and travelled along the outside of two other foundation walls.
The cure was to dig up the corner to expose the outside of the foundation. Once there we removed the broken blocks, pushed the wall back into place and replaced the broken blocks with new ones. The extent of the damage to this foundation meant we had to reinforce the other walls with carbon fibre straps as well so the walls did not move again in the future.
Because we had the exterior exposed we waterproofed the foundation and replaced with weeping tile system as well. This particular project was completed in order to have a new kitchen installed directly above so it was key to straighten & reinforce the foundation so the new kitchen could be built on a solid and straight foundation!
Degraded mortar joints
If you own a house that was built in and around the 1940’s we find that the mortar used back then was not as strong as the mortar commonly used today. If the right conditions exist on the exterior side of the foundation, conditions such as having clay soil, water over saturating the area and bad grading you will find that over time the mortar joints start to disintegrate.
Shown in this example picture you can see how the mortar joints have totally disappeared and the one’s around that area are in very poor condition. Usually what we find in this situation is that the exterior side of the foundation is worse than the inside. Most times you can simply push the blocks right out onto the floor. When this is the case we recommend that section of the foundation be rebuilt as it has lost its connection point to the other blocks via the mortar joints.
Stair step cracks in mortar joints
This is a common condition often found in block foundations that are surrounded by clay soil and the affected area being saturated with water. The stair-step cracking will follow the mortar joints in a foundation wall and are typically found at corners on buildings.
Frost heave or expanding soil heave throughout the seasons is what produces this type of damage. Also know that temperature & moisture can also cause both step cracks and vertical cracks even where no settlement is occurring.
If your foundation movement has a hairline step crack like it is very unlikely that it is a major repair situation but if conditions persist and the cause of cracking is not found and corrected it could lead to further damage. We always recommend you find the source of the problem, start by controlling roof runoff and getting it away from the building. An interior inspection would also help see what is going on.
For foundations that have step cracks that are 1/8” – ¼” or more we would recommend you hire a structural engineer to inspect your foundation. We know from past experience that when this condition exists there is a good chance that some additional work may take place. The foundation may need some extra supports under it such as peering with the addition of a waterproofing system.