How to stop a leak in a foundation wall

What is the best way to stop a leak in a foundation wall?
The best way to stop a leak in a foundation wall is to waterproof the exterior. However, this is not always cost effective. So, when waterproofing isn’t an option, you may be able to stay dry using epoxy injections.

The first step is to determine what kind of leak you have: Is it a weeping or trickling leak, or is it gushing? Does it happen when it rains a lot or is it random?

Interior plumbing issues can typically get ruled out by noticing if a leak corresponds with the weather or plumbing usage. Other causes are not always as simple. First-is the leak coming in from a crack in a foundation wall? If it is: consult a licensed structural engineer, because you never want to treat the symptom before you know the cause.

The engineer will determine what type of crack it is and how to repair it. Is it a cyclical crack? Is it a progressive crack with a structural concern? For more information, please see this previous post on foundation cracks. If the engineer determines that a crack is not a symptom of a structural problem, they may recommend epoxy injections.

My engineer recommended epoxy injections…What is that? How does it work?

Epoxy injections are a process in which we inject your wall with some type of resin epoxy. The goal with epoxy injections is always to fully penetrate the wall as much as is possible and keep water out. This is why we drill injection ports in order to administer the products as far within the wall as we can. Then we continuously flush the wall with water to clean out the dirt embedded in the cracks and to react with our epoxy. The video below shows the whole process:

Many different factors are involved in choosing and administering the right product for the job. There are different types of resins for different applications. In selecting one, we must consider:

- The volume of leak, weeping or gushing?
- Size of the crack or defect.
- Accessibility of the site.
- What are the environmental conditions: weather, moisture levels, temperatures, etc.
- Expansion rate, set time, and viscosity of the product.
- Physical properties of the reacted product.

For a weeping leak the thickness, or viscosity of the product matters most.
When we inject a weeping or trickling crack, we want our resin to “find” every nook and cranny and penetrate the crack as much as possible to seal it against water intrusion. This means we need a low-viscosity product that travels quickly to where we need it and penetrates everywhere that does.

For small weeping cracks we often use a flexible, water-activated polyurethane injection resin. This resin is hydrophilic; meaning it is attracted to water and will ‘find’ the path that the water takes and seal those areas. It is typically used for sealing actively leaking joints and cracks in concrete structures. As it reacts to water, it expands to fill the space and bonds to the concrete, creating a closed barrier that does not allow water to pass through or around it. Furthermore, this foam’s flexibility allows it to expand and contract along with the structure it has sealed, so it remains watertight despite temperature fluctuations.

If you have a gushing leak or large water flow, the primary concern is fast setting time and expansion rates. In order to stop the leak, the resin must react with the water present and expand quickly enough to form a watertight, rigid foam before it washes away.

We use a hydrophobic (repels water) structural resin for gushing leaks. When mixed with a catalyst, it becomes a water-activated polyurethane foam with low viscosity and a variable set time that can expand 2000 times its size. It is used to seal gushing leaks, including wide gaps, in concrete where the structure is not subject to movement. Typically injected under pressure using injection ports, it acts as a water cut-off for gushing leaks, filling voids, slab lifting/stabilizing and permeating loose soils to increase their load-bearing capacity.

How do you seal large cracks on the surface prior to injections?

In order to surface-seal cracks prior to injections you need products with a high viscosity to fill in those areas before you inject the wall. So, for larger cracks we use two-component epoxy gel adhesives before we inject the wall.

Can I do my own injections?

Next to waterproofing, epoxy injections are a great way to stop a leak in a foundation wall, and they do sell kits to do them yourself. However, in our experience this is one project that I would avoid tackling on your own. There are a few reasons for this.

You absolutely need to rule out structural problems with an engineer before attempting to repair any cracks. Once the epoxy goes in, you cannot undo it, making future repairs potentially more difficult and expensive.
Warranty-You have the peace of mind knowing the work is guaranteed and knowing that this warranty is transferable should you want to sell your home.
Documentation that you repaired your wall correctly and did your due diligence can make home sales go much more smoothly.
We are specially trained in the use and application of these high-quality professional grade products. You cannot buy them (or our expertise) at your local home improvement store.