Your driveway's expansion joints might not be the first thing you inspect when you walk outside, but they play a critical role in protecting your concrete. When joints fail, they silently channel water under your slabs, causing erosion that leads to cracking and sinking. Here are five clear signs that your expansion joints need attention — before the damage spreads.
1. Visible Gaps Between the Joint Material and Concrete
Walk along your driveway and look closely at the joints. If you can see gaps between the filler material (usually plywood or fiber board) and the edges of the concrete slabs, water is already getting through. These gaps form as the filler shrinks, rots, or shifts over time. Even small gaps can channel a surprising amount of water beneath your concrete during a heavy rain.
Run a flathead screwdriver along the edge of the joint material. If it slides easily into a gap, the seal is compromised.
2. The Plywood Is Dark, Soft, or Crumbling
Healthy wood is firm and maintains its color. If the plywood in your joints has turned dark brown or black, feels spongy when you press on it, or crumbles when touched, rot has set in. This is one of the most common signs we see in Central Texas driveways, especially those older than five years.
Rotting plywood is not just failing to seal — it is actively absorbing moisture and holding it against your concrete, which can accelerate deterioration of the concrete edges themselves.
3. Weeds or Grass Growing Through the Joints
If vegetation is growing up through your expansion joints, it means the old filler material has deteriorated enough to allow soil, seeds, and moisture to accumulate. While pulling the weeds might make it look better temporarily, the real problem is below the surface. Those roots are pushing the remaining filler apart, creating even wider channels for water.
Weeds in your joints are a clear visual indicator that the seal is no longer functional.
4. Water Pooling Near or Along the Joints
After a rainstorm, take a look at your driveway. If you notice water pooling specifically along the joints or draining into the joint lines rather than sheeting off the surface, the joints are acting as troughs. This is exactly the scenario that causes soil erosion beneath your slabs.
In some cases, you might even see the water disappearing into the joint — visibly flowing down through the gap. That water is going directly under your concrete and washing away the support base.
5. Cracks or Uneven Slabs Near the Joints
This is the most serious sign because it means damage has already begun. If you notice cracks running from or near the expansion joints, or if adjacent slabs are sitting at slightly different heights, soil erosion has already undermined the concrete support. The slabs are losing their foundation and beginning to fail.
Hairline cracks near joints are an early warning. Significant cracking or noticeable slab movement means you need to act quickly to prevent further damage. If your slabs have already shifted or sunk, Hill Country Slabs can help with concrete leveling to restore the surface before you seal the joints.
What to Do If You See These Signs
If you spotted even one of these warning signs on your driveway, it is time to replace your expansion joint material with a proper silicone seal. At Seal My Joints, we handle the entire process: removing the old material, installing backer rod, and applying professional-grade silicone that lasts 10 to 20 years.
The sooner you act, the less damage water can do beneath your concrete. Sealing starts at just $999 — a small price compared to the thousands you could spend on concrete repair down the road.
Get your free quote or call us at (737) 287-4308. We respond within hours and serve all of Central Texas including Austin, San Antonio, and surrounding areas.