The short answer
Check the Patio Slope
The patio should slope away from your home, usually about a quarter inch per foot. If the concrete settles or was poured flat, water has no reason to drain off and will follow the path of least resistance, often straight toward the sliding door. You can test this with a level or simply pour a bucket of water and watch where it goes.
If the slope is wrong, the fix may involve mudjacking or re-pouring a section of the patio. That is a job for a concrete professional. In the meantime, you can use temporary barriers like sandbags or a rubber threshold to keep water from entering during heavy rain.
Inspect Gutters and Downspouts
Clogged gutters or downspouts that discharge too close to the foundation can dump large volumes of water onto the patio. That water then flows across the slab and toward your door. Clean the gutters regularly and extend downspouts so they carry water at least several feet away from the house.
Heavy summer downpours can test your drainage system quickly. A simple downspout extension is often enough to redirect the flow. Also check that the ground near the downspout slopes away from the patio rather than pooling against it.
- Clean gutters and downspouts before rainy season
- Extend downspouts at least 5 feet from the foundation
- Check for leaks or loose joints in the gutter system
- Make sure the ground near the downspout slopes away
- Consider a rain barrel or dry well to manage overflow
Look at the Door Seal and Threshold
Even with proper drainage, a worn or missing door seal can let water sneak under the sliding door. Inspect the rubber gasket at the bottom of the door and the sweep on the stationary panel. Replace any cracked or brittle pieces. The threshold itself should be level and firmly attached to the slab.
A small gap of even a quarter inch can let a surprising amount of water inside during a heavy storm. You can also apply a bead of exterior-grade caulk along the bottom edge of the threshold where it meets the concrete. That seals out minor seepage without affecting the door's operation.
Address Landscape Grading
The ground around your patio can direct water toward the house if it slopes inward. Walk around the perimeter and look for low spots where water collects. Build up the soil so the grade falls away from the foundation. You can use topsoil and compact it, then plant grass or ground cover to hold it in place.
If the patio sits lower than the surrounding lawn, water will naturally flow onto it. Raising the grade or adding a swale (a shallow ditch) can redirect runoff away from the door. For larger grading changes, you might need to consult a landscaper or excavation professional.
Know When to Call the Pros
If you've checked the slope, gutters, seals, and grading but water still flows toward the door, the issue may be deeper, like a broken drain line or a high water table. Persistent flooding can damage the door frame, subfloor, and drywall over time. You might notice musty odors or staining near the base of the wall.
Local water damage pros can inspect the area and identify the source of the water. They can also dry out any affected materials and help you plan a fix. Acting quickly reduces the risk of mold and structural damage. If you see standing water inside, move furniture away and dry the area as well as you can.
- Call a professional if water keeps entering despite your fixes
- Look for signs of water damage like stains or soft spots
- Dry wet areas within 24 to 48 hours to prevent mold
- Keep your insurance policy handy in case you need to file a claim
Water damage does not wait
Call (386) 272-5697 any time, day or night, and describe what happened.
Call Now (386) 272-5697Frequently asked questions
Can I fix a low spot in my patio myself?
Small low spots can sometimes be filled with concrete patch or leveling compound. Larger settling issues usually need mudjacking or re-pouring, which is a job for a concrete pro. If you're unsure, test with a level and watch how water behaves.
Why does water come under the door even when it's not raining?
If water appears without rain, check for a leaky sprinkler, a broken irrigation line, or a high water table. The patio may be sitting in saturated soil. A plumber can inspect underground lines, and a water damage pro can help find the source.
Will my insurance cover patio flooding damage?
Policies vary, and your insurer decides what is covered. Flooding from a storm may be excluded unless you have separate flood coverage. Water from a burst pipe or sudden leak is often covered. Check your policy and talk to your agent about your specific situation.