The short answer
Find the Source First
Before sealing anything, trace where the water is entering. Check the crack's location: is it in the foundation, a wall, or the floor slab? Look for signs like damp spots, efflorescence, or peeling paint. Knowing the source helps you decide whether a simple patch will work or if the problem is bigger.
In a humid climate, spring storms can saturate the ground quickly. If the crack is below grade, the water likely comes from hydrostatic pressure. That means you need to address drainage outside, not just patch the crack. Check gutters, downspouts, and grading around your home.
Seal Small Cracks Yourself
For hairline cracks (under 1/4 inch), clean the area with a wire brush and remove loose debris. Apply a hydraulic cement or a polyurethane crack filler, pressing it into the crack with a putty knife. These products expand as they cure, creating a watertight seal.
Let the patch dry completely, then test it with a hose or wait for the next rain. If water still seeps through, the crack may be wider than it appears or the pressure is too high. In that case, a deeper repair is needed.
Use a wire brush to clean the crack
Apply hydraulic cement for below-grade cracks
Use polyurethane sealant for above-grade walls
Smooth the patch with a trowel
Let it cure for 24 hours before testing
When to Call Local Water Damage Pros
If the crack is wider than 1/4 inch, runs through structural walls, or water keeps entering after patching, call local water damage pros. They can assess whether the crack is a sign of foundation movement or just a surface issue. They also have tools to inject waterproofing materials deep into the crack.
For active leaks, the pros may need to extract standing water first and dry the area before any sealing. This prevents moisture from being trapped behind the patch, which can lead to mold or further damage. Their work typically involves both the crack repair and the surrounding moisture control.
Cracks wider than 1/4 inch
Water keeps coming back after sealing
Cracks in load-bearing walls
Signs of foundation settling or shifting
Improve Drainage Around Your Home
Surface water is a common cause of cracks leaking. Ensure your gutters are clear and downspouts direct water at least 5 feet away from the foundation. Regrade the soil so it slopes away from your house, and consider adding a French drain if water pools near the base.
In a humid subtropical climate, heavy rain can overwhelm poor drainage. Check the grading after a storm and before sealing cracks. Fixing the outside problem often stops the inside leak entirely, saving you from repeated patching.
Prevent Future Cracks
Once the crack is sealed, keep an eye on it during the next few rainfalls. Look for new cracks nearby, which may indicate ongoing movement. Maintain your gutters and downspouts, and avoid planting trees too close to the foundation, as roots can cause pressure.
If the crack was caused by water pressure, consider improving the soil compaction around your home or adding a drainage system suited to your climate. Regular inspections after heavy storms can catch small issues before they become big leaks. If you're unsure about the cause, a professional inspection can help.
Check gutters and downspouts twice a year
Keep soil level below the foundation sill
Avoid overwatering plants near the house
Watch for new cracks after heavy rain
Talk to someone now
Phones are answered 24/7 for Rockwall and nearby communities.
Call Now (469) 698-4610Frequently asked questions
Can I use caulk to seal a crack that leaks water?
Caulk is not ideal for water leaks. It is flexible but may not withstand hydrostatic pressure. Use hydraulic cement or an epoxy-based crack filler instead. These are designed to expand and seal against water. For exterior cracks, a masonry sealant can work.
Why does water come through cracks only after heavy rain?
Heavy rain saturates the soil, increasing hydrostatic pressure against your foundation. That pressure forces water through any existing crack. If the crack is below grade, drainage improvements often help more than sealing the crack alone. Check the grading around your home first.
Is a leaking crack a sign of foundation problems?
It can be. Hairline cracks often appear from normal settling, but wider or recurring cracks may indicate foundation movement. If the crack is structural, sealing it alone won't fix the issue. A professional inspection can determine if the foundation needs repair.