Waterproofing cinder block basement walls is an extremely common practice, particularly in older homes. Unfortunately most repairs on this type of foundation can be rather prohibitively expensive depending on the extent of waterproofing required.
In this blog post we’ll shed a little light on basement leaks common to concrete block and cinder block foundations. We also provide information on standard waterproofing industry repair solutions for the most common types of basement leaks.
The most common causes of cinder block foundation leaks
- Cracks in the block or mortar joints;
- Seepage through the bottom of the blocks;
- Leaks between the floor slab and the foundation wall;
- Water coming up from below the floor slab
- Water penetration around or below window frames and through basement windows; and
- Leaks originating at the top of the basement foundation wall.
The most commonly encountered basement leaks in cinder block foundations are attributed to cracks in the mortar joints between the blocks, or leakage through the windows or around the window frames. Most of the leaks in this type of foundation can be repaired either from the outside by the traditional method of excavation and waterproofing, with a waterproof membrane or coating however, some instances can be repaired from inside by installing an internal drainage system.
Traditional basement waterproofing = Excavation
Excavation and waterproofing, the most universal option for stopping concrete block basement leaks, is very effective in stopping basement leaks as long as the repair is executed correctly and the most appropriate materials are used (this is not always a given). External waterproofing involves the following steps:
- Excavation of the problem area, either by hand or by machine;
- Exposing the entire problem area; which sometimes may be difficult to visually identify on the outside;
- Cleaning of the foundation wall;
- Applying either a waterproof coating and membrane to the surface; and
Click on this link for a lot more detail on this type of foundation repair
Waterproofing your foundation on the exterior may not fix your basement leak
It should be noted that this method, while it is generally all-encompassing, does not solve all basement leaks. Excavation and waterproofing cinder block basement walls will only solve leaks that originate from cracked blocks or mortar joints. Waterproofing exterior foundation walls will not work at all if there is a basement leak due to a high water table or insufficient window well drainage. Also, when it comes to determining the extent of work that needs to be performed, a professional waterproofer would have to make an assessment from the interior either by examining the bare concrete block wall for leaks and damage or using a moisture-reading instrument.
Generally, when there is a basement leak in a concrete block foundation it is usually not isolated to a small area and larger areas are typically affected due to the way the hollow cells of the blocks are aligned, as they are stacked in a diagonal fashion.
Another point to note about exterior excavation and waterproofing is that it is expensive and time consuming to undertake and that generally you would need to do at least a minimum amount, as set by the contractor, in order to meet his costs. This is something to take into consideration when budgeting for waterproofing work.
The alternative to excavation is the Internal Drainage system, Perimeter Drain system or Internal Weeping Tile System
This system for solving basement leaks in concrete block foundations is becoming increasingly popular as an alternative to excavating. The reason for this rise in popularity is that it is roughly a quarter of the cost, it can be done in sections, or piece by piece, it requires less time to undertake and it is far less destructive than excavating.
How the Internal Drainage system works:
- Walls are exposed to the bare cinder block (internally);
- A trench is created in the floor along the affected area;
- A drain pipe is placed beside the footing the length of the breakout;
- A membrane is installed to direct the water to the pipe;
- The pipe then drains to a sump pit where the water is evacuated; and, finally,
- New concrete is poured along the breakout.
Click on this link for more information on this system for waterproofing cinder block basement walls.
- Any instance of basement foundation leak
- Leaks through blocks
- Leaks at floor joint
- Water under the floor (this indicates a high water table and a sump pump installation is the only way of correcting the problem)
As previously stated, there is certainly a large difference in price between internal and external waterproofing methods and both have their respective applications. However, when one encounters a high water table, which allows water to make its way beneath the footing, or when excavation is not a viable option, an Internal Drainage system is the best choice.
Make sure to consult a knowledgeable and professional waterproofing contractor when planning on waterproofing cinder block basement walls. The right contractor will assist you in determining the best and most cost-effective solution for your specific needs.