There is no storm. The sky is clear, the wind is light, and there is six inches of water across the end of the street. It came up through the storm drains an hour ago and it will go back down them in another hour, and in the meantime every car coming home drives through it and parks in a garage.
That water is not rain. It is the sea, arriving by the drains, and for a garage door it is a different problem from anything a hurricane does.
Why the autumn tides are the high ones
The highest tides of the year in South Florida arrive in the autumn, usually from September into November. The astronomy that produces a very high tide lines up in those months, and the ocean is also at its warmest and highest along this coast at the same time of year, so the two effects stack.
In the low-lying parts of Fort Lauderdale and the neighbourhoods behind the Intracoastal, the result is flooding on a sunny day. Water rises through the drainage system, because the outfalls that are supposed to let rainwater out to sea are below the level of the sea for a few hours.
Nothing about that is news to anyone who lives on those streets. What is less obvious is what it does to the bottom of a garage door, which is the part of the house that sits closest to it.
Salt air is a mist. This is a bath.
We have written before about the bottom six inches of the lift cables, and why coastal corrosion concentrates at floor level. Salt air delivers chloride slowly, a little every night, in a film of condensation.
Tidal flooding delivers it all at once, in liquid, directly onto the bottom brackets, the bottom seal retainer, the lowest hinge and the ends of both tracks. Even when the water never reaches the door, it arrives anyway, on four tyres, and drips onto the slab right in front of it.
Then the water evaporates and the salt stays. That is the part that matters most.
Salt that stays on the floor keeps working
Sea salt is hygroscopic: it pulls water out of the air. A dried salt film on a garage floor does not sit there inertly. On a humid night it draws moisture back in and becomes a brine again, right where the track ends are anchored to the slab and right under the bottom bracket.
So a single tide can keep corroding the bottom of the door for weeks afterwards, on dry days, with no further water involved. It is also why a garage a few streets back from the water, on a street that floods, can show more rust at floor level than one nearer the water that sits higher.
The fix is almost insultingly simple, and it only works if it is done soon.
What to do the same day
- Rinse the floor along the door with fresh water. A hose and a push broom, working the water out of the garage rather than further in. The aim is to carry the salt away, not to spread it.
- Rinse the bottom edge of the door from outside, with the door closed. Aim low: the seal, the bottom corners and the base of each track where it meets the floor.
- Look at the tyre tracks. The line where the car parks is where the brine dripped. If it runs close to a track, that end of the track deserves the most water.
- Let it dry with the door closed, then run it once and listen. A new scraping sound at the bottom of travel is worth noting before it becomes worth calling about.
Do not reach behind the bottom bracket or try to clean the cable where it attaches. That bracket is under full spring tension whenever the door is down. Water from a hose is the right amount of contact.
What the bottom seal can and cannot do
The rubber seal along the bottom of the door is a draught, debris and insect seal. It is not a flood barrier and it was never designed as one. Standing water at the threshold will come under it, around the corners and through any low spot in the slab.
Removable flood barriers that fit across the garage opening do exist, and on a street that floods on every high tide they can be a sensible thing to own. They go on the opening, not on the door, and they come off before the door is used.
The money question
No prices. The ordinary end of tide damage is a bottom seal and its retainer, a pair of bottom brackets, and a pair of cables, which is one visit. The expensive end is a corroded track base that has let go of the slab, or a bottom section that has rusted through from the inside because brine got into the edge and never came out.
What decides which end you are at is almost entirely whether the salt was rinsed off the week it arrived, which is a hose and ten minutes.
What not to buy
- Do not buy a heavier bottom seal expecting it to hold back a tide. It will seal better against wind and insects. It will not keep out standing water.
- Do not buy a flood barrier that fixes to the door. Anything attached to the door adds weight the springs were not set for, and it is in the way exactly when the door needs to move.
- Do not buy a replacement bottom section for surface rust. Rinse it, look again in a month, and replace it when it is actually failing.
- Do not replace cables without looking at the brackets they hang from. On a door that sits in tidal water, the bracket is usually worse.
The short version
Autumn brings the year’s highest tides, and on low streets they bring seawater onto the slab in front of the garage door. The salt stays after the water leaves and keeps working on humid nights. Fresh water, the same day, removes most of the problem.
This is not the first article on this site whose main advice is a garden hose. We are aware of the pattern. It keeps being the right answer.
M&M Garage Door Service · (954) 787-3756 · mnmgaragedoorrepair.com
Serving Plantation, Fort Lauderdale and Broward County.