NextStar Support Articles for Concrete Foundation and Crack repair
Support for concrete crack and foundation repair

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 Selecting the right kit is usually based on the size of the crack that you are dealing with and determining if it is structural are not. Most foundation cracks are not structural and can be repaired using polyurethane products, polyurethane has the advantage of expanding when it becomes in contact with water expanding filling any voids thus creating a permanent gasket. Polyurethane foams come in a few different viscosities so one must determine the crack size and select the proper polyurethane.

The exception for use of polyurethanes is with ultra fine cracks that are less than 1/64 of an inch wide especially for use with low-pressure crack injection and in these cases we use and ultra low viscosity epoxy that is injected under constant pressure or gravity fed. ULV epoxy is also used to repair snap ties or wire ties that were left behind when the concrete was poured, exterior sealing over the snap ties may have failed over time allowing them to rust and allow water through. Ultra fine foundation cracks are the most difficult types of cracks to repair and require some patience to permanently repair. The usual method would be to ULV epoxy under constant pressure over a period of time to allow the epoxy fully fill the smallest cracks and flaws, this epoxy has the advantage of being slow curing thus allowing extended injection times. Our kit 3 uses an auto injector system that allows the epoxy to be injected under constant pressure without the applicator having to babysit the repair. Standard methods would require either asked spring-loaded application tool or a pneumatic injector to accomplish this and for some cases this may be at one time repair and having to purchase specialty tools may be cost prohibitive.

LV polyurethane foam is used for cracks that are from 1/64 of an inch to 1/32 of an inch that have been leaking and can be injected using auto injectors, low-pressure injection or high pressure Packers. LV polyurethane foam is a single component all urethane that has an activator added just before injection and will stay active for approximately 7 days.

Standard 102 polyurethane foam is our standard injection product for most leaking basement walls and problems, it is true two component polyurethane that is mixed just before injection and chemically reacts with water to that can expand over 20 times its volume size. Standard 102 can be used on cracks from just less than 1/16 of an inch to up to 3/8 of an inch wide and will be completely cured usually within a few hours but will stop water immediately. Standard 102 polyurethane is available in several formats, one in our kit 1 auto injector system and with our semi Pro DIY systems 10 ft 20 ft 30 ft kits. Contractors can purchase the 102 polyurethane in standard dual tube sets.


120 structural foam structural foam is used to fill large voids and gaps in walls such as where pipes have been removed. This product cures very fast and requires it to be injected as quickly as possible as it expands aggressively, it will also build up a fair amount of heat in the process. 120 structural foam does not require water to be present for the chemical reaction and is typically used for cracks that are from 3/8 of an inch to 1 inch wide. Wide cracks must be also supported using carbon fiber Staples or grid straps, structural foam cannot be crushed but has no tensile strength for bonding a wall and thus the requirement for carbon fiber reinforcement. It is a good substitute for epoxy in this case to help reduce cost of the repair.


Epoxies in general epoxies are excellent products that can be used to stop leaks and effectively glue the wall or concrete back together but have the disadvantage of added cost as they do not expand during injection and in some cases product can be lost to the exterior of the wall during injection leading to the use of more epoxy. Epoxies are generally required for all structural failures as the epoxy itself is much stronger than the concrete is being used to repair, and have been used in the repair industry for many years. Epoxy usually requires the use of dual component injection tools or pneumatic tools and do take a little bit more time to complete a successful repair. The use of epoxy for repair has the advantage that should the crack reopen or the injection fail it can be re-injected. If a wall is injected with polyurethane it cannot later be injected with epoxy and may cause a problem if the original repair was a structural failure. Structural failure refers to walls that have bowed in or cracks larger than 3/8 of an inch wide and in some cases if you are unsure we would recommend that you have a structural engineer examine the foundation first. There may be other underlying problems with the foundation that have caused the cracking simply not bad concrete or lateral force on the wall.

Nextstar support articles for concrete crack repair, Leaky basement and foundation crack repairs. Support for product use and methods of repair of cracked concrete including. Articles for homeowners and contractors alike
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