Gunite is often used in basement construction and repair. The versatility of gunite makes it a good choice for repairs, and it adds strength while leaving a smooth surface. Gunite can be sprayed into foundation cracks with little or no prep work and it not only adheres to previous applications of gunite, it can also be applied to most surfaces including cracked concrete and crumbling rock walls.
Gunite (occasionally called dry gunned concrete) is a form of sprayed concrete, and is similar to shotcrete but with gunite the water is mixed with the dry mixture of cement and aggregate at the nozzle as it is being applied. The nozzle man adjusts the amount of water that is added to the mix and has total control of the cement to water ratio. The mixture is sprayed at high velocity to create a smooth concrete surface. Gunite is often sprayed over rebar or steel mesh in new construction for added strength, and can be sprayed into basements, pools, retaining walls, water gardens, and even overhead.
The interior walls of the gunite basement construction are often covered with a plaster coating to waterproof the basement. The plaster is similar to what you would find on the surface of a swimming pool. This plaster covering will occasionally crack and chip making the wall look bad and leaving an area unprotected as far as waterproofing goes. To repair these cracks you need to chip away all loose material and remove debris from the surface. Once the area is prepared you can make the repair by simply replacing the plaster coating.
Changes in temperature and settling of the ground can cause larger cracks to appear in your basement walls and floor. If you have a crack in your basement that goes beyond the surface coating and into the gunite it can be repaired a few different ways. First you can choose to repair using an epoxy compound by filling in the crack. Kits are available for the do-it-yourselfer to repair small cracks in foundation and basement walls.
A second way of repairing your basement wall is to fill it in using a concrete stitching system that places staples across the crack. These staples are made to keep the crack from opening any further. To place the staples you would need to drill holes for the staples and remove the surface coating in the area where the staples are going to be installed. Once you have the staples in place you can fill in the crack using any type of non-shrinking fast setting cement.
If the damage to the basement is extensive enough you may choose to repair it using gunite. This can be done even if the original basement was not constructed of gunite. Gunite will adhere to most surfaces. It is best to have a trained professional blow the gunite into your basement because if the wet to dry mix ratio isn’t correct or if the gunite isn’t blown in correctly (and evenly) you can have some structural problems.
Repairing an existing basement with gunite requires that you put an even coating of gunite over the surface. Shooting the gunite over the surface will fill cracks in and strengthen the surface. Applying gunite to your basement repairs any cracks and chips you may have and it will make your basement look like new.