Interior vs. Exterior Doors: What Actually Changes

A slab is the door panel alone. A pre-hung unit is the slab already mounted in its jamb with hinges installed, and for exterior openings it includes the sill and weatherstrip.

Buy a slab when you are replacing a door into a jamb that is square, solid and staying. Buy pre-hung for new construction, for any exterior opening, and any time the existing jamb is out of square — which, in an older house on a slab that has moved, it usually is.

Interior doors are called out by a four-digit code: the first two digits are width in feet and inches, the last two are height. A 3068 is 3 ft 0 in. wide by 6 ft 8 in. tall.

We stock sixteen standard interior sizes — widths from 1'4" through 3'0" in both 6'8" and 8'0" heights. Every door style page lists which sizes that style is available in.

Fiberglass is what we recommend for most entries here. It does not rot, it will not warp in the sun the way wood does, the foam core insulates well, and textured skins take stain convincingly.

Steel is the budget option and is fine on a protected entry, but it dents, and it gets extremely hot in direct West Texas sun. Wood is beautiful and needs real maintenance on any door that gets afternoon exposure.

Glass configuration is the other decision: full lite, three-quarter, half lite, or a solid panel door. More glass means more light and less privacy and insulation — south and west entries in particular benefit from less glass than people expect.

Handing is the single most common ordering error on pre-hung doors, and it is not returnable-friendly once a unit is bored. Stand outside the door — on the side you would push from to enter — and look at the hinges. Hinges on the left is a left-hand door; hinges on the right is right-hand. If the door swings toward you from that position, it is a reverse (outswing) unit.

Bring a photo of the opening to the counter if you are unsure. It takes thirty seconds to confirm and it prevents a mistake that costs weeks.