Sealing exterior concrete joints is a key step in preventing moisture intrusion, extending surface life, and maintaining structural integrity. Whether dealing with sidewalks, driveways, parking lots, or industrial floors, using the right sealant and applying it correctly can prevent costly repairs down the road. Here are four essential factors to consider before you seal your joints.
01. Is the joint a control joint or an expansion joint?
Not all joints serve the same purpose. The type of joint you’re sealing determines the best product to seal your joints.
- Control Joints are placed in concrete to manage shrinkage and minimize random cracking. These joints typically don’t experience significant movement but still need sealing to prevent water infiltration and debris accumulation.
- Expansion Joints allow concrete slabs to expand and contract with temperature changes and movement. These joints require a flexible, high-performance sealant that can stretch and compress without losing adhesion.
Using the wrong sealant for the joint type can lead to premature failure, cracking, or separation over time.
02. What is the joint going to be exposed to?
Exterior concrete is constantly exposed to weather, moisture, and chemicals. The right sealant should match the environmental conditions of the job site.
- Moisture & Freeze-Thaw Cycles: In areas prone to heavy rain or freezing temperatures, a water-resistant and freeze-thaw-stable sealant is necessary to prevent water infiltration and joint failure.
- UV Exposure: Some sealants degrade when exposed to prolonged sunlight. If the joints are in an uncovered area, choose a UV-stable product to prevent hardening and cracking.
- Chemical Resistance: In industrial areas or roadways where deicing salts, fuel, or other chemicals are present, a chemically resistant sealant is needed to prevent premature breakdown.
Selecting a sealant that withstands these environmental factors ensures long-term protection and reduces maintenance needs.
03. What sort of traffic will each joint be expected to carry?
The amount and type of traffic passing over the sealed joint play a major role in choosing the right product to seal your joints.
- Heavy Vehicle Traffic: If forklifts, trucks, or heavy equipment will pass over the joint, a high-strength, abrasion-resistant sealant is required.
- Pedestrian Traffic: In areas with only foot traffic, a flexible sealant can be used, but it should still be durable enough to prevent early wear.
- Slip & Trip Hazards: In walkways or public spaces, the sealant should cure to a smooth, level finish without becoming too rigid or brittle.
A properly selected sealant will hold up to wear and tear, preventing cracking and material failure under stress.
04. Does the joint have any fall or slope in it?
The orientation of the joint determines the best sealant consistency for the job.
- Sloped or Vertical Joints: Use a non-sag sealant that stays in place after application.
- Flat, Horizontal Joints: A self-leveling sealant is ideal for ensuring a smooth, even fill without the need for tooling.
Choosing the correct type of sealant ensures proper adhesion and prevents sagging or pooling in the joint.
Properly sealing exterior concrete joints prevents water damage, extends surface life, and minimizes costly repairs. By considering joint type, environmental exposure, traffic conditions, and joint orientation, you can choose the right sealant for long-term durability and performance.
Check out our product selection guide for exterior control and expansion joints:
Product Selection Guide for Exterior Control & Expansion Joints
