Odd sized exterior door options

Question

One of our many projects last year was to replace our back exterior door. It is in a converted porch, unfortunately, which means it's an odd size.

Specifically, it's 75-76" x 30". Unfortunately, none of that is negotiable - more than 30" and the door opens over the steps to the basement, and more than 76" and the jamb would be cutting into the structural supports. It's also not straight, because the porch has a bit of a lean to it.

Last year, we bought one of these, a 30x80 composite wood door, from Home Depot. We cut it down to the requisite size - managed to do a decent job of that, amazingly - and installed it.

Unfortunately, despite being an "exterior" door, the wood started peeling almost immediately. This is Northern Illinois, so a bit harder on doors than warmer locations, I suspect.

The question is, what options do we have here? What's our best bet to get something that will last at least a few years? I suspect eventually we'll take out the porch and make improvements to extend the whole house back some - our house is the shortest in the neighborhood in terms of how much of the lot is used by the house itself - but that's 5-10 years down the road at least.

• Buy another slab, cut it down again, and try better finishing options.
• Buy a steel slab, like this one, and cut it down - but can you cut a steel door like that?
• Find an all-hardwood slab door that can be cut down (do these exist?)
• Something else?

Is there a "best" approach here that doesn't involve a few grand for a custom door? Is that the only real solution to this kind of problem that won't need replacement every year or two?

Answer 1

Some suggestions:

• Regardless of the door type, a good coat of primer and exterior paint will be the better of the finishing options.

• a fiberglass or steel surface should outlast a wood one (they should both be 'trimmable' with the right saw blade)

• Check to see if your door slab could benefit or be harmed with the inclusion of a storm doors. Some doors benefit (water protection) other's can be damaged by it (over heating in the sun).

• consider ripping out the entire door and door jamb and installing a whole new all-in-one pre-hung exterior door. This will allow you to re-square up the opening and also likely give you the most water-tight seal.

Answer 2

Have you considered a GRP composite door? It may not fit with the style of your house, and I don't know availability in the US, but I bought myself a custom made one online for £600, and self-installed it. That's about $1000, rather than the "few grand" you are expecting a custom door to cost.

Answer 3

Yes, you can cut down a steel door smaller, but I would not call it simple. I have a steel door from Home Depot similar to the one you reference, which I shortened by half an inch.

I would only attempt to change the height of a steel door like this by a small amount; no more than an inch or two. 5 inches height change would require some major reconstruction. And I would not attempt changing the width, due to the way the steel is bent and fits into a slot in the wood.

All the steel doors I've seen are constructed similarly. There is a wooden frame inside, making up the top, bottom, and two edges. And there are two steel skins attached to the wooden frame, for the two faces. They are bent over around the edges and press fit into the wood. The top and bottom are just 90-degree bends, but the side edges are bent into a "U" or "J" shape that fits in a slot in the wood frame.

On my door, I carefully unfolded the bottom edge of the steel, pulled out the wood bottom frame piece, cut it shorter, and trimmed half an inch off the steel sheet metal using shears. Then I replaced the wood bottom, and carefully folded over the steel to wrap around the wood. It was slow and fussy to get it even, and it still warped and buckled a minor amount. Fortunately none of it is at eye level.

The wooden frame inside the door is a few inches wide, so if you want to trim off 5 inches, it will require peeling back the steel to reconstruct the wood frame. Since the steel is folded on 4 edges, it will want to kink and buckle a fair amount on the sides.

I would recommend getting a steel or fiberglass door only if you get a custom door made to size. If you're going to cut one down, use a solid wood door.

Definitely look into repainting your existing door with a better primer and paint. Instead of latex or acrylic, look at oil-based or alkyd paint, such as Rustoleum, which will stand up to weather better. Yeah, it smells worse and is more trouble to clean up, but for only one door it is worth the trouble.

Answer 4

Simply special order the right sizes for a rough opening. If you can start fresh, wait a week or two and get a good fit that will last. You can cut like a consumer said if need(if its your property, and you're OK with it). If you're an installer its not recommended.

Answer 5

Just did a similar fix on a split level basement exterior door with concrete walls and 7 foot ceiling. bought a pre-hung fiberglass and trimmed the frame width so the door sits against the inside wall but the threshold sits out to the edge and the door is taller than the opening so it almost touches the low ceiling on the inside. Attached 4x4s to the wall using concrete anchors on each side of the door jamb. attach the jamb to the 4x4. Painted it up and looks cool.

The door opens and thee exterior height is only showing a few inches so painted that piece of concrete to remind me that its lower than the door opening.