Door Specification Review

Finding Out What You Are Actually Being Sold

A garage door quote is usually a colour, a panel style, a window option and a price. The parts that decide whether the door is still straight and quiet in twelve years are rarely on the page.

A specification review puts them there. We look at what you have, or at what you are being offered, and write down the four things that matter: steel gauge, insulation type, layer count, and the grade of the hardware going in with it.

Gauge, and Why the Scale Runs Backwards

Sheet steel thickness is quoted in gauge, and gauge counts down. Higher number, thinner steel.

In residential doors you will meet 27, 26, 25, 24 and, less often, 21 and below. 27 and 26 are thin. 25 is builder grade, the steel that goes on a tract house because it is cheap and it looks the same on handover day. 24 is the ordinary residential middle and is a genuine step up. 21 gauge is heavy, noticeably so when you lift a section, and it is what you fit when a door takes abuse.

The gap between 25 and 24 sounds trivial written down. It is roughly a quarter more steel, and it shows up in dent resistance, in how the panel holds its line across a sixteen foot opening, and in how long the paint stays flat over it.

Telling Polystyrene From Polyurethane

Both get sold as insulation and they are different products doing different jobs.

Polystyrene is a rigid board, cut to size and slipped into the pan behind the front skin. It insulates. It is not bonded to anything, so it adds no stiffness, and over the years it can work loose and rattle when the door runs.

Polyurethane is injected as a liquid, expands to fill the section, and cures bonded to both skins. That bond turns a pressed sheet into a sandwich panel. The section gets much stiffer, the door runs quieter, and the foam cannot shift because it is chemically stuck to the steel.

You can usually tell which you have in a minute. Look at a section end cap or along the bottom of the lowest panel. A loose white board with visible beads is polystyrene. A dense, slightly yellow foam that is clearly stuck to the steel is polyurethane.

Counting Layers and Struts

Single layer means one skin and nothing behind it. Cheap, light, loud, and easy to dent from the inside as well as the outside.

Double layer is a front skin, insulation, and a thin vinyl or polymer backer that mostly exists to keep the insulation in place and stop it looking unfinished from the garage.

Triple layer adds a real steel back skin. Between two steel skins and a bonded core, the section becomes properly rigid. Most of what people describe as a quality feel in a door is layer count doing its work.

While we are looking, we count struts. A strut is the horizontal reinforcing bar across the back of a section. Wide doors need them, and leaving a couple off is one of the quietest ways to shave cost out of a quote. A sixteen foot door short on struts will bow visibly within a few years.

Hardware, Which Matters More Here

Two miles from the water the door skin is not usually the part that fails first. We check track thickness, hinge gauge, roller type, whether bearings are sealed, whether springs are galvanised or plain oil tempered, and what the fasteners are made of.

Then the spring cycle rating, which is the one nobody volunteers. A cycle is one open and one close. A 10,000 cycle spring on a door used four times a day is roughly seven years. A 25,000 cycle spring on the same door is closer to seventeen. They hang on the same shaft and look the same.

What You Get

A written summary of what the door in front of you actually is, what a quote in front of you actually offers, and where we think the money is worth spending on your particular opening. Frequently that includes telling you the expensive option is not worth it.

Call (657) 958-9661.