Water coming in under the garage door

Water entry problem

What the water is telling you

A wet garage floor after a storm is more than an annoyance. The pattern of the water is a clue. A thin, even line along the whole bottom edge points at a seal that no longer touches the floor. A puddle in one corner points at a low spot, a tilted door or a damaged section of seal. A sheet of water that pushes in across the entire width points at drainage outside.

Before you assume the door is the only culprit, remember that the door is only one part of a small system. The apron outside, the slab inside, the bottom seal and the way the door closes all work together to keep water out. When one of those four changes, the others are asked to do more than they were built for.

Houston weather makes the question harder, because the climate is humid and the rain can be heavy and wind driven. Water that would run past a straight door in a gentle shower can be pushed sideways under it in a storm. That is why a door that stayed dry for a long time can suddenly start leaking in one particular rainfall.

It also helps to separate a leak that began suddenly from one that crept in slowly. A sudden change often follows an event, such as a vehicle bumping the door, a storm that shifted something, or a seal that finally slipped out of its channel. A slow change usually points at aging materials and settling. Knowing which one you have gives the technician a place to start.

The bottom seal and why it stops sealing

The flexible strip along the bottom edge of the door is designed to press against the floor and close the small gap that every door has. Over time that strip hardens from heat, splits along its length, flattens from constant contact or slips partly out of the channel that holds it. A seal that has lost its springiness no longer follows the floor, so water finds the gaps.

You can check this safely with the door closed. Look along the bottom edge from inside with a flashlight in a dim garage, and see whether daylight shows through anywhere. Run your hand along the seal and note if it feels brittle, cracked or stiff. If you can see torn pieces or a section that hangs loose, our page on a torn bottom seal goes into the details.

Replacing a seal is usually a modest job compared with other garage door work, but the right type matters. Some doors use a bulb style strip, some a T shaped insert and some a flap that mounts on the outside. The profile has to match the channel in the door, which is one reason to describe the door to a technician instead of guessing at a part from a photo.

• Look for daylight under the closed door along its full width.
• Press a finger along the seal and notice any hard or cracked spots.
• Check that both ends of the seal are still seated in the bottom channel.
• Note whether the seal looks flattened in the middle where the floor is highest.

Low spots, slope and the apron outside

Many Houston driveways and slabs are quite flat, and that flatness is part of the story. If the apron outside the door slopes toward the garage instead of away from it, rain will gather at the threshold and press against the seal. Even a very slight slope in the wrong direction is enough, because the seal only has to stop a thin film of water.

Settling can change this over time. Soil moves with wet and dry seasons, and a slab can sink or tilt a little. A door that once met the floor evenly may now have a gap at one end. This is also why you may see water enter at only one corner during a storm.

A technician can tell you whether the door can be adjusted to follow the floor better, but a sloped apron or a broken slab is not something the door itself can fix. If you suspect a drainage issue, take a few photos during the next rain showing where water pools. That evidence helps whoever looks at it, whether that is a door technician or someone who works on concrete and drainage.

When the door itself does not sit flat

Sometimes the seal is fine and the door is the problem. A door that hangs slightly crooked, or that stops a little short of the floor, leaves a gap that no seal can cover. If one side is higher than the other, the low side may drag while the high side lifts. Our pages on a crooked garage door and a gap at the bottom of the door explain how that happens.

Bent or loose bottom brackets, a sagging section or tracks that have moved a little can all change where the bottom edge lands. The change is often small enough that you only notice it when the weather turns. Water is very good at finding a gap of a few millimeters, and it will do so at the lowest point.

If you see the door land unevenly, stop using it as normal and describe what you see. Do not try to adjust cables, springs or bottom brackets yourself, because those parts hold stored tension and can cause serious injury. A trained technician can check balance and alignment together, which is safer and gives a more reliable result than adjusting one thing at a time.

How water entry leads to rust and rot

Water under the door is not only a floor problem. Moisture sitting at the bottom edge works on the lowest parts first. On a steel door, the bottom panel edge and the hardware near it can start to rust. On a wood door, the bottom rail can soak up water, swell and eventually soften.

Hardware suffers too. Rollers at the bottom, the bottom brackets and the lower ends of the tracks sit right where splashes land. Rust makes metal rough, which adds friction and noise, and it weakens thin brackets over time. Our pages on rusty garage door hardware and swollen wood garage doors describe what that looks like.

The practical point is that a leak is a reason to act sooner. A seal is usually a smaller repair than a bottom panel or a set of corroded brackets. If you catch it early, the repair can stay small and the door can keep working smoothly through the humid months.

Paint and finish matter as well. A scratched or worn bottom edge on a steel door exposes bare metal to repeated wetting. Wood doors need their bottom edge sealed so the grain does not drink up moisture. Mention any peeling paint or dark staining along the bottom when you talk to the technician, because it shows how long water has been reaching that spot.

What you can safely check yourself

There are several observations that are safe and useful. With the door closed, look at the seal, the floor and the threshold. Sweep away leaves and grit from the bottom edge and the track area outside, because debris can hold the seal off the floor or keep the door from seating. Watch where the water enters during the next rain and note it.

Keep your hands away from the bottom corners while the door moves, since the lower brackets and cable ends are under tension. If the door is stuck or off track, leave it alone. Pulling on a door that has moved can bend the tracks or let a section fall.

Also pay attention to what you store near the door. Cardboard boxes, paper and fabric on the floor soak up water and hide how bad the leak is. Raising items onto shelves or plastic bins costs nothing and protects your belongings while you sort out the cause.

• Sweep the bottom edge and the area just outside the door.
• Photograph the water line and the wet spots during or right after rain.
• Move stored items off the floor near the door.
• Leave springs, cables and bottom brackets alone.

What to tell the technician

When you call, describe what you saw rather than what you think the part is. Say whether the water comes in along the whole width or in one spot. Mention whether the seal looks cracked, flat or missing, and whether the door sits evenly on the floor. If you know the door is steel, wood or aluminum, that helps too.

Tell the technician about any noise or change in how the door moves, since that can show a balance or alignment issue behind the leak. Mention if you have noticed rust or swelling on the bottom of the door. These small details let the technician arrive with a better idea of what to look at.

During the visit, the door and its seal are inspected on site, and the options are discussed with you before any work begins. That discussion should cover whether a new seal is enough, whether the door needs adjustment, or whether the real fix lies outside, such as drainage. It is reasonable to ask which of those the technician sees and why.

Seal choices and what they change

Seal material is a real decision. Vinyl and rubber behave differently in heat and over many months of contact, and some profiles press more firmly than others. Our comparison of vinyl and rubber garage door seals lays out the tradeoffs, and the guide to types of weatherstripping shows the other pieces, such as side and top seals.

The bottom seal is not the only weather barrier. Side seals along the jambs and a top seal across the header keep wind driven rain from sneaking around the edges. If the bottom is sealed well but the sides leak, you can still see water inside. A full look at all four edges is more useful than a look at the bottom alone.

For more on this service, see our page on weatherstripping and insulation. It covers how seals and insulation are chosen to suit the door you have, rather than forcing one product onto every garage.

One more point is the order of work. If the door is crooked, worn at the rollers or out of balance, a new seal alone may not hold for long, because the bottom edge will keep landing unevenly. Sorting out alignment first and then fitting the seal gives the new strip a fair chance to do its job. Ask the technician whether anything about the door's movement should be corrected before the seal goes on.

Heavy rain, storms and flood season

Houston gets strong downpours, and tropical storm and hurricane season brings wind that pushes water sideways. A seal that is good enough on a calm day can be overwhelmed in those conditions. Think of the seal as a barrier against ordinary moisture, not a flood gate.

If you live where water can rise around a home, a garage door seal will not hold back standing water. For that kind of risk, read our guide on flood season garage door preparation and our notes on storm preparation. Those pages cover how to plan ahead without making promises about outcomes.

What your property needs depends on its location, the slab and the surrounding drainage, and requirements vary by city and community. Your city or your insurer can tell you what applies to you. A garage door technician can describe what the door can and cannot do, but cannot speak for those rules.

Attached garages, storage and what is at stake

Most Houston garages are attached to the house and double as parking, storage and a workshop. That means a leak is rarely just a wet floor. Water can wick into the bottom of drywall, stored cardboard, tools, lawn equipment and the lower edge of the door that connects to the house. A small leak that repeats through a wet season can slowly spoil more than you notice at first.

Humidity matters here as well. Even when no water enters directly, damp air and a poor seal let moisture settle on cold concrete and metal surfaces. You may see a musty smell, white powder on the slab or spots on stored items. These are signs to look at the seal and the ventilation together, which our guide on humidity and your garage door discusses.

If your garage shares a wall with living space, take leaks more seriously, and consider how the water might travel. A simple habit helps: after each heavy rain, look at the floor along the door and the lower walls. Catching dampness in the first season is much easier than finding it after it has spread.

When to stop and call

Some situations mean you should stop and make a call instead of waiting. If the door will not close all the way, if it tilts as it moves, or if you see a frayed cable or a bent track, stop using it and keep people and cars clear. A door that cannot close is also a security and weather problem, so it deserves prompt attention.

If water has reached the opener, the wall control or any outlet in the garage, do not touch them. Keep away from wet electrical equipment and let a qualified person assess the situation. Opener parts and wiring are not designed to sit in water.

For a plain leak with a working door, you have time to gather photos and notes before calling. When you do call, our team can talk through what you describe. If you are in Houston or a nearby area, the page on garage door repair in Houston explains how that first conversation goes.

Questions and answers