Concrete Expansion Joint Repair
Concrete Expansion Joint Repair is a common exterior job. Homeowners typically spend about $19 on materials if they tackle it themselves, while hiring a professional usually runs $100–$250 depending on access, parts, and local labor rates. DIY can save up to about $231 versus a full pro job when the work stays straightforward.
Expect roughly 1-2 hours for a careful DIY attempt versus about 45-60 min for a seasoned pro. Difficulty is rated 2/5 (approachable for most DIYers) with low risk. Typical materials include backer rod, polyurethane sealant, sand. Common tools: caulk gun, utility knife, shop vacuum.
Use the sections below to weigh DIY against hiring: cost ranges, safety alerts, common mistakes, and a personalized analysis for your ZIP code.
Typical Cost
Cost estimates based on cataloged material prices and regional pro rates. Run the analysis for US-wide retailer prices and a regional professional-cost estimate. How we estimate costs.
Is this a DIY job?
AI-assisted educational guidance — not reviewed by a licensed professional. Review policy.
- Typical DIY time1-2 hours
- Typical pro time45-60 min
- Permit requiredNo
What affects the cost
- Local labor rates for exterior pros and whether the visit is emergency vs. scheduled.
- Brand and quality of parts (backer rod, polyurethane sealant, sand) versus economy alternatives.
- Access difficulty (tight spaces, multi-story work, finished surfaces that must be protected or repaired after the job).
When to hire a pro
- If you feel dizzy, short of breath, or develop a rash, leave the area, ventilate, and seek medical help if symptoms persist.
- If a tool binds, overheats, or you are unsure of safe technique, stop and reassess or hire help rather than force the cut.
- High-impact DIY mistake — Incorrect Sealant Choice: Choose a polyurethane sealant specifically designed for concrete expansion joints.
- When hiring a professional to repair your concrete expansion joint, be sure to describe the issue in detail, including the location and size of the joint. Provide photos or videos of the damage to help the contractor understand the scope of the project.
- Ask the contractor to include the cost of materials, labor, and any necessary permits in their quote. Be wary of low-ball estimates, as they may indicate a lack of experience or a desire to cut corners.
- Check the contractor's credentials and reviews to ensure they have experience with concrete repair. Ask about their process for ensuring a proper seal and their warranty or guarantee policies.
- Before the repair begins, confirm that the contractor has obtained any necessary permits and that you understand the payment terms and schedule.
- Verify ladder safety and insurance for height work
Hazards & safety alerts
-
medium chemical Chemical exposure and fumes
Products used for concrete expansion joint repair can irritate skin, eyes, and lungs. Poor ventilation multiplies exposure during mixing, sanding, or curing.
Stop and call a pro if: If you feel dizzy, short of breath, or develop a rash, leave the area, ventilate, and seek medical help if symptoms persist.
-
medium injury Cut, puncture, or tool injury
Tools used for concrete expansion joint repair can cause deep cuts, eye injuries, or kickback. Rushing or skipping eye/hand protection multiplies the chance of injury.
Stop and call a pro if: If a tool binds, overheats, or you are unsure of safe technique, stop and reassess or hire help rather than force the cut.
Materials you'll need
| Material | Est. Price |
|---|---|
| backer rod | $5.00 |
| polyurethane sealant | $10.00 |
| sand | $4.00 |
| Total (DIY materials) | $19.00 |
Tools: caulk gun, utility knife, shop vacuum
DIY steps
- Before starting the repair, ensure your safety by wearing protective gear, including gloves, safety glasses, and a dust mask. Clear the area around the expansion joint of any debris or obstructions. Use a shop vacuum to remove any dirt or dust from the joint.
- Use a utility knife to remove the old, damaged sealant from the expansion joint. Cut the sealant at a 45-degree angle to create a clean surface for the new sealant. Remove the old sealant completely, taking care not to damage the surrounding concrete.
- Cut the backer rod to the correct length and insert it into the expansion joint, ensuring it's seated properly. This will provide a solid base for the new sealant.
- Apply the polyurethane sealant to the backer rod, using a caulk gun to fill the joint completely. Hold the gun at a 45-degree angle to ensure the sealant fills the joint evenly.
- Use a damp finger or tool to smooth out the sealant, feathering it out towards the edges to create a seamless finish. Allow the sealant to dry completely, following the manufacturer's instructions.
- Once the sealant is dry, inspect the repair to ensure it is even and smooth. Do not use sand in the expansion joint; if the cured sealant is defective, remove it and reapply compatible sealant so the joint remains flexible.
- Dispose of any leftover materials and clean your tools thoroughly. Inspect the repair one last time to ensure it's complete and satisfactory.
Common DIY mistakes
-
medium Insufficient Surface Prep
Failing to properly clean and prepare the surface can lead to a poor seal and reduced durability.
-
high Incorrect Sealant Choice
Using the wrong type of sealant can lead to premature failure or damage to the surrounding concrete.
-
medium Inadequate Backer Rod
Failing to use a backer rod or using one that's too small can lead to a poor seal and reduced durability.
-
low Poor Sealant Application
Applying too little or too much sealant can lead to a poor seal or mess.
-
medium Inadequate Drying Time
Failing to allow the sealant to dry completely can lead to a poor seal or damage to the surrounding concrete.
Frequently asked questions
- How much does it cost to fix a concrete expansion joint?
- DIY materials typically run about $19. Hiring a pro usually costs $100-$250 depending on your area and the scope of the job.
- Can I fix a concrete expansion joint myself?
- It depends on the job. Difficulty is rated 2/5 and risk level is low. Run the free analysis on RepairSmart for a personalized DIY vs. hire recommendation.
- What are common mistakes when you fix a concrete expansion joint?
- Common DIY mistakes include: Insufficient Surface Prep; Incorrect Sealant Choice; Inadequate Backer Rod. See RepairSmart for the full list and cost breakdown.
- What safety hazards should I watch for when working on concrete expansion joint?
- Key hazards include: Chemical exposure and fumes; Cut, puncture, or tool injury. See RepairSmart for stop-conditions and the full safety list.
Not sure? Get a personalized recommendation
RepairSmart compares US-wide retailer prices with regional pro costs and gives you a weighted DIY-vs-hire recommendation in under 60 seconds.
About these estimates
- Numbers on this page come from the RepairSmart catalog (materials baselines and typical pro ranges). They are educational estimates, not contractor quotes.
- Personalized ZIP analysis may add live or cached retailer prices and regional pro signals when third-party data is configured.
- Read how costs and DIY scores are calculated, our safety & review policy, and about RepairSmart.
- If guidance is marked unreviewed, treat steps and tips as educational only—not a professional sign-off for your home.