Naples · Collier County
A strip of daylight under a shut garage door looks like a sealing problem, and sometimes it is. Often it is the door telling you that something has moved — and in Naples the consequences are not just comfort. That gap is the route in for water in a heavy rain, and for everything that lives in a Florida yard.

Five causes cover almost every one of these we see in Naples. They are not equally likely, and they are listed in roughly the order we find them.
UV and heat destroy the astragal faster here than almost anywhere. It hardens, cracks, flattens and stops conforming to the floor. The cheapest item on this list and the most common cause.
The opener stops the door short of the floor. Often appears after opener work, a spring change, or a new floor coating, and it is a setting rather than a part.
Many Southwest Florida garage floors are not flat, and some have settled. The door is straight and the floor is not, which leaves a wedge of light at one end. A bulb seal or a threshold seal is the right answer rather than forcing the door down.
Impact, water damage or corrosion along the bottom rail changes the line the seal sits on. The gap is usually uneven along its length, which is the giveaway.
If the gap is wedge-shaped rather than even, the door is not sitting level — and that is a cable, spring or track question, not a seal question.
Do not fix it by setting the down-limit further and pressing the door into the concrete. The door then lands hard on every cycle, the opener reads the resistance as an obstruction and starts reversing, and the bottom section takes the load it was not built to take.
The point of the visit is to find the cause, not to replace the first plausible part. On a call like this in Naples:
Inside the city limits you are almost never more than a mile from the Gulf, and that shows up in the hardware long before it shows up in the door skin. Salt-laden air off the water settles on the torsion shaft, the bearing plates and the bottom of the lift cables, and the first sign is usually a groan on the way up rather than anything visible.
The housing here is largely single-family homes on small lots, many with the garage set back off an alley or a side lane, and a growing number of three-car garages on rebuilt lots, with 1950s and 1960s cottages sitting next to 2015-onward rebuilds on the same street. Around Old Naples, Aqualane Shores, Port Royal, Coquina Sands, the Moorings and Park Shore that shapes which of the causes above turns up most often.
On the salt-exposed addresses, corrosion moves the odds. Cables, bearings, drums and even sensor terminals go before anything visible does, which is why a fault like a gap under a closed door here is checked at the hardware rather than judged by the look of the door. Galvanised and stainless specification is the correct answer in Naples, not an upsell.
What it costs. A bottom seal is one of the least expensive parts on a garage door, and on a Florida coast address it is close to a consumable. What costs money is treating a square problem as a seal problem and fitting seal after seal. We quote starting-from figures and we do not close a price before seeing the door. No call-out fee, no diagnostic fee, and no evening, weekend or holiday surcharge.
Depending on what we find, this call often ends up being one of these:
If the door is generally tired rather than faulty, a full service and the right wear parts is usually the better call, and we will say so.
More than people expect. During a heavy summer storm, driving rain across a driveway finds a half-inch gap easily, and garage floors generally slope inward at the back rather than out. It is also the standard route in for rodents, snakes and insects.
A standard astragal will not. A bulb seal with more compression, or a threshold seal bonded to the floor, is designed for exactly that and works where a flat seal cannot. Which one depends on how much the floor is out.
Marginally on its own, and more if the garage is conditioned or shares a wall with living space. The bigger effect is humidity — a gap keeps the garage at outdoor dew point, which is hard on anything stored there and on the opener.
Less than most people assume. UV, heat and — near the water — salt take a standard seal down in a few years rather than ten. It is worth checking at the same visit as the annual service.
Then the first question is not the seal. A wedge-shaped gap means the door is not hanging square, which points at a cable, a spring or the track. Worth looking at properly before anyone fits a new seal.
Yes, and it is usually the sensible way to do it — the same visit covers the seal, the rollers, the cables and the balance, with no call-out fee and no diagnostic fee.
You get the price before anyone drives out, and if you decide not to go ahead you owe us nothing.