What to Know Before You Buy a Steel Door

Low-E stands for low emissivity. It is a very thin metallic coating on one of the inside surfaces of an insulated glass unit that reflects radiant heat while letting visible light through. In a cold climate it keeps heat in. In Central Texas the job is the other way round: keeping the sun's heat out, which is the main thing driving a cooling bill through an Austin summer. On any door or window facing west or south, we consider it close to essential. Our standard glazing is 1/4 inch clear tempered glass, and Low-E insulated units are the most common upgrade. The glass options page covers Low-E, laminated, tempered and low-iron glass and where each one belongs.

Steel conducts heat well, which is a problem when the frame runs straight from the outside of the house to the inside. A thermally broken frame has an insulating strip built into the profile that separates the outer steel from the inner steel, so the heat path is interrupted. The results you notice: the inside of the frame is closer to room temperature, condensation on the frame in winter mostly disappears, and the door contributes less to the cooling load. Non-thermally broken frames cost less and are fine for interior doors, covered openings and wine rooms. For an exposed exterior door in Texas, we recommend the thermal break. The energy efficiency page goes through insulated cores, seals and glazing as well.

If you want the thin-framed, lots-of-glass look, only steel gets you there. If you want a solid panel door with no glass on a budget, fiberglass is a reasonable choice. Wood is beautiful and needs the most attention in this climate.

A single door is simpler, seals on three sides against a fixed frame, and suits openings up to roughly four feet wide. Beyond that, or when you want the entrance to open fully for furniture and gatherings, a pair makes sense. A pair needs an astragal where the leaves meet, flush bolts on the inactive leaf, and a bit more care in installation to keep the meeting gap even. If you want the width of a pair but mostly use one leaf, a single door with sidelites gives a similar look with simpler hardware. See single doors, double doors and doors with sidelites.

Every door we build is made to order, so the honest answer is that it depends on size, configuration, glass, finish and hardware, and we quote each project individually with installation included. The things that move the price most are overall size, the number of operable leaves, thermally broken frames, Low-E or laminated glass, and specialty hardware. Measure your opening, pick the configuration you like from the products page, and request a quote. We come back with a firm number, not a range.

• A welded frame and slab, not screwed or crimped sections, so nothing racks or loosens.
• Thermally broken profiles on exterior doors.
• Insulated glass with a quality edge seal, tempered or laminated as the location requires.
• Multipoint locking that pulls the door evenly into its seals.
• A proper finish, applied over prepared steel, with a touch-up supply for later.
• Heavy-duty hinges sized for the slab weight, adjustable where the door size calls for it.
• Installed by the people who built it. The best door in the world does not perform in a badly set frame.

They can be, and the three things that decide it are the frame, the glass and the seals. A thermally broken frame stops the steel conducting heat straight through. Low-E insulated glass handles the large glass areas these doors are known for. Good weatherseals compressed by a multipoint lock stop air leakage, which is often a bigger loss than conduction. A steel door with all three performs well. A steel door with none of them is a radiator. We build to the first description. Details on the energy efficiency page.

The lock does two jobs: security, and compressing the seals. On a large steel door a multipoint lock does both better than a single deadbolt, and we fit it as standard on most exterior doors. Beyond that, the choices are handle style, finish and whether you want a keyed cylinder, a smart lock or both. Pick a finish that will live happily next to the door finish and the other exterior metal on the house. The locksets page walks through the options.

• Lead time from order to installed door is usually a little under two months. Most of that is fabrication.
• Final measurements are taken by us, on site, before anything is cut.
• Shop drawings are issued for approval. Check the handing, the glass layout and the hardware before signing, because that is what gets built.
• Finished floor height, exterior cladding and any trim need to be decided before the measure, not after.
• Installation is included. Site preparation (framing, flashing membrane, finished floor) is the builder's or homeowner's.
• Tell us about anything unusual: a sloped site, a stone surround, a pool nearby, an alarm contact, an existing smart lock.