Injection epoxy resins and urethane foam systems are the two most widely used materials in the repair of leaking cracks in concrete basement walls. Crack injection (with either injection epoxies, polyurethane foams, or polyurethane grouts) is the best and most economical method for repair of a leaking crack on the wall of a poured foundation. When the basement has a crack that needs to be structurally repaired and the area needs to be as strong or stronger than the concrete around it, use an epoxy. The main advantage of epoxies is their amazing compressive strength, which at 12,000 psi or greater exceeds that of most concrete. If the crack needs to be repaired only to prevent water leakage or the crack is actively leaking, a polyurethane is usually the best choice. Polyurethane products are typically elastomeric, fast-setting foams which are effective alternatives for applications involving only crack sealing (waterproofing) and not structural repair. Because of their elastomeric nature, they are able to accommodate slight concrete movement so the seal stays intact.
Concrete Surface Preparation
Remove loose or flaking concrete with a wire brush or sand blast the surface to ensure proper bond of the surface seal paste. It is important to clean surface to ensure bonding of ports.
Installing Injection Ports
Surface ports are most commonly used for low-pressure injection into concrete wall cracks. The older method of installing ports was to drill into crack on an angle to inject either the epoxy or polyurethane into the center of the crack. Today most ports are installed directly onto crack and the crack is then sealed with a surface sealer which allows injection at up to 40 psi pressures. Concrete cracks can move when exposed to a temperature cycle that normally occurs in a 24 hour period unless crack has been injected with foam or epoxy. Injection of crack should be done no later than 6 hours after sealing surface.
Foundation Crack Repair Injection
Product is injected at 20-40 PSI into the lowest port on the wall until the epoxy or urethane begins to flow from the port above it. That port is then capped and work continues to port located directly above. This procedure is repeated until the entire crack has been filled with the epoxy or polyurethane. Product should be topped up after 20 min or so to replace any sealant that has leaked out to the outside.
Foundation Finish
The ports can be removed by striking with a trowel or hammer. If cosmetic appearance is preferred, the surface seal can be chipped, ground (with sanding disk), or burned off. The surface seal is paintable if grinding is not desired. Wear protective clothing and breathing apparatus while grinding. If cosmetic appearance is preferred, the surface seal can be chipped or grounded off (with sanding disk).
The Barrie Home Inspector frequently comes across cracks in foundations that have been repaired using crack injection method. Some new home builders have their own crack injection specialist. As in any other trade you want to research whoever you choose for any repair. Length of time and experience is very important and also verifying references should be a priority. The Tarion Home Warranty program will not consider a crack in a basement wall a deficiency unless it is over 6mm in width or water is leaking from it. Concrete is not flexible and with the weight of entire structure being transferred to the footings a small amount of settlement can be expected.
Injection epoxy resins and urethane foam systems are the two most widely used materials in the repair of leaking cracks in concrete basement walls. Crack injection (with either injection epoxies, polyurethane foams, or polyurethane grouts) is the best and most economical method for repair of a leaking crack on the wall of a poured foundation. When the basement has a crack that needs to be structurally repaired and the area needs to be as strong or stronger than the concrete around it, use an epoxy. The main advantage of epoxies is their amazing compressive strength, which at 12,000 psi or greater exceeds that of most concrete. If the crack needs to be repaired only to prevent water leakage or the crack is actively leaking, a polyurethane is usually the best choice. Polyurethane products are typically elastomeric, fast-setting foams which are effective alternatives for applications involving only crack sealing (waterproofing) and not structural repair. Because of their elastomeric nature, they are able to accommodate slight concrete movement so the seal stays intact.
