Applying Elastomeric Caulk for Concrete

crack in concrete
  • 1-3 hours
  • Beginner
  • 0-100
What You'll Need
Paint brush
Elastomeric sealant caulk
Plastic spatula/putty knife
Plastic bucket
Backer rod
Pry bar
Joint sealer

Among various caulks used for basic, household repairs and woodworking projects, elastomeric caulk has become a popular option. Caulk is an easy-to-handle sealant and is widely used to repair cracked concrete surfaces. Aging concrete surfaces tend to crack along the seams and if they are not properly repaired, the cracks can turn into wide, difficult-to-repair gaps. Caulking is also recommended when undertaking home-improvement projects like painting the walls. The presence of a caulked concrete surface ensures the paint is evenly spread and the walls are guarded against moisture.

Elastomeric Caulking Basics

There are various kinds of caulking materials. Elastomeric caulks contain a higher consistency of acrylic ingredients, making them more durable. It is regarded as the most stretchable and quick-setting option among contemporary caulks. Elastomeric caulk is particularly useful for caulking concrete surfaces exposed to sustained moisture seepage, like the crawlspace and bathroom.

Elastomeric caulking is the most recommended choice for repairing any domestic structure that plays a role in the temperature or heat insulation of the house. This is why elastomeric caulk is also called weatherproofing material. Elastomeric caulking is able to form stronger, heat-resistant bonds that prevent leakage of air. To repair a concrete surface with elastomeric caulk, use the following instructions.

Step 1 - Get Prepared

large crack in cement foundation

Before applying the caulking material, clean the gap to ensure there is no debris. This is critical to ensure proper bonding between the concrete surface and the caulking material. Use a paint brush for this purpose. You can pour a few drops of water in the crack before applying the caulk. This ensures any remaining debris sticks to the surface and doesn’t hamper the bonding process.

Step 2 - Handle Small Concrete Repairs

Elastomeric caulk sold in easy-to-apply tubes can be applied directly to smaller, cracked surfaces. Smaller cracks are less than ¼ inches in width. The caulking tube may have a foiled seal or a fused-tip seal. Both of these can be easily opened by puncturing the marked opening area with a needle. However, if the tube has an application-end without a pointed opening, you need to cut it. Using a knife or scissors, cut the applicator-end at a 45-degree angle. Ideally, the size of the cut made on the applicator should be a bit smaller than the hole you need to repair. Direct the cut, or the pinched end of the tube into the gap. Squeeze the tube, ensuring the caulking material is forced deep into the hole. Let the repaired gap dry for a day.

Step 3 - Handle Large Concrete Repairs

crack in concrete

If the concrete surface has gaps that are larger than ¼ inches, you need to use a backer rod. The backer rod is a thin, string-like tubing material that is applied to the insides of larger concrete holes. Pour the caulking material into a plastic bucket. If you use fillers, use a plastic spatula to scoop it out and mix it with the elastomeric caulk. Position the backer rod inside the gap and start pouring the caulking material. Use the spatula to direct the caulk upon the backer rod tubing. Presence of backer rod ensures the caulking mix is directed towards every internal fissure/crevice within the repaired gap.