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This is a question many homeowners ask contractors before embarking on repair of wall cracks. It is right to be concerned about your health and the possible effects of chemical compounds introduced to your home.

There are various compounds used for fixing wall cracks. The type of compound used will depend on the method of repair being used.

  1. Crack injection

Crack injection is the most popular method for repairing cracks from the interior. The injection of the cracks helps to prevent water from seeping into the basement. The process involves injecting either epoxy paste or an expanding urethane compound into the crack.

  • Epoxy: These are non-toxic. They are used to cement small cracks. They can also be used to cover cracks after urethane has been used to seal the cracks and prevent water seepage. Epoxy has been in use since the 1920’s. It was first used as an adhesive and later as a finish for floors and a component in paint.

Epoxy is a polymer resin. When it is combined with a hardener, it dries quickly and becomes a hard plastic that is water resistant. It gives off a smell but is completely non-toxic. This smell dies away when the epoxy has cured.

  • Urethane: This is usually injected into a crack to fill it and seal it against penetration of water. Urethane is highly flexible even after curing. It is however impermeable to water and therefore makes a great seal in concrete foundations that are affected by movement. The urethane plug will move with the concrete without cracking.

Urethane is also non-toxic. It is a common compound in various plastic products including food packaging and water bottles. It is chemically inert. You can be sure that the product will remain the same for its lifetime in your wall.

  1. Wall clay process

This is the second method of repairing wall cracks in foundations. It is used to repair cracks from the exterior of the foundation wall. It involves the use of bentonite clay. The clay is applied to the cracks and allowed to cure. When the clay is exposed to water it expands. This results in the formation of a tight seal.

Sodium bentonite is the primary ingredient in the clay used for foundation repair. It is a naturally occurring material that is extracted from the earth. It is completely harmless.

Be sure to check with your contractor to find out if the compounds they are planning to use on the foundation are harmful.