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How to seal cracks in a concrete wall

Cracks in concrete walls can quickly expand into larger cracks as moisture starts to seep through. It is important to repair concrete cracks as quickly as possible, as basement walls must maintain structure. The smallest amount of water can cause building materials to rot and create mould and mildew.

Concrete cracks are relatively simple to repair as long as they are fixed reasonably quickly. In this blog, we will share product recommendations and tips to ensure that your concrete sealing project is successful.

To start, here is a list of supplies you will need;

-Putty Knife 

-Gloves (preferably waterproof) 

-Brush -Nylon or wire brush 

-Scraping tool 

-Concrete Repair Material 

– Job Dependent 

-Cleaning solution 

-Small Mixing bowels and something to mix it with.

Before starting to seal the concrete cracks, you will want to check. Is there flowing water in the crack, or is it dry or damp? Is it a hair line crack or larger?

We recommend using the Crack Pack Epoxy Injection kit for hairline cracks. This kit is good for cracks that are 1/64” to ¼” wide. The surface can be damp; however, if it's flowing water, you need another product. The Crack Pack Kit comes with everything you need aside from the caulking gun. Most homeowners do have a caulking gun lying around in their garage. This system works by adhering ports to the wall and then injecting epoxy through they entire wall thickness. Start injecting from the bottom port and work your way up until the last port. Let sit overnight and then you can break off the ports using a hammer. If this is an exposed wall and you want it to look aesthetically pleasing, you can grind off Paste. If not, it can be left on and you can finish and prep the wall for drywall.

If you had flowing water, you will need to open the gap with a crack chaser blade and chisel. This must be channeled out, so be sure you open it up to 1" wide and 1.5" deep. This system is made by Kryton and will be messy and require a lot of time. After its been chiselled out, you will need to mix four parts of the Krystol Plug with one part of clean water (mix to a putty consistency, but only mix as much as you can mix and place within one minute. The colder the water, the better for mixing (Ice cubes in the water help tremendously). This trick slightly slows down the set time.

Using a glove, take the Plug and press and hold it firmly into the leaking seeping crack while the material is still pliable. Press and hold still for approximant of one minute - keep repeating this step until the entire chase has been filled. Make sure when filling the chase the Plug is only applied no thicker than 0.5". There will be some more product later required to fill the chase completely. Use a trowel or chisel to ensure all leaking water stops flowing before proceeding. You may need to do some touching up. Scrape off. Make sure all leaking water has stopped flowing before proceeding. Again, you may need to do some touching up.

After this step, wash the crack until the water runs clear, but ensure the crack is Saturated Surface Dry (SSD). This means wet the surface but not having any standing water before proceeding.

Next, you will need the Krystol Repair Grout; you want to mix this into a stiff, putty-like consistency. Start with four parts Krystol repair grout to one part clean water. Keep in mind your ice cube trick! By the time you get to this step, you will be a pro! You may add up to half of the powder to obtain a stiffer, sag-free paste. While mixing, it may seem dry at first, but the more you mix it, the more it will become smooth and pliable. If the grout sags while installing it, mix in more powder until it holds/sets in place. Tightly press, pack the grout, and fill the entire chase until it is level with the rest of the wall. Be sure not to leave any voids. If working exteriorly, protect this area from rain or freezing for the next 24 hours. When mixing, only mix as much material that can be mixed and placed within 20 minutes.

Step three: Final Step is using Krystol T1. Once all active leaks have been stopped, you can coat the entire surface with the T1 to ensure permanent waterproofing. This can be done by mixing approximately 3.5 parts powder with 1 part clean water. Make sure the area again is Surface Saturated Dry (SSD). If it is not SSD, the bond between the two products may be weak and dust or flake off. This material can be brushed on with a heavy brush, broom or even a texture sprayer. This will be a pancake batter-like consistency, brush and coat the entire surface to about 1.2-1.6kg/m2 and this can be applied in one or two coats. If using in two coats, be sure to have the second coat applied within 48 hours after the first coat, and make sure the wall is SSD between coats! Your first coat should be set hard between 6-24 hours, depending on the temperature. Make sure you are generous with your coats and cover at least 12” or so on both sides of the cracks. It will not hurt to go farther.

If applying outdoors, be sure to protect the area from the elements. You can begin to wet cure as soon as the Krystol coating has hardened and will not be damaged by curing water, usually in 6-24 hours, depending on temperature. Keep it covered during the curing period to retain as much moisture as possible. Apply more curing water if the coating dries out during the curing period. If backfilling is necessary, this can be done after the coating has set hard. If you need to backfill within the first three days, make sure to use a damp backfill material.

Each job is unique and different, be sure to contact your local Concrete Specialist to ensure the correct products are utilized for your job.