How to put a smaller door in a larger door frame.
March 20, 2005 11:24 PM   Subscribe

I need to rip an extra-wide door out of our shed and put in a new narrower one. The door frame consists of substantial timbers -- I'm guessing around 3x8 (actual measurements). The floor is cement, there's no bottom frame member. What's the best way to replace the door?

Our shed was built by the previous owner, an almost-do-it-yourselfer. He put in a door that swings upward, balanced by a cinderblock on a super-strong thin cable. Fun if you're six years old. I'm wondering what my best option is here, in terms of security and do-ability. I'm leaning toward actually chiselling out a n-inch deep hole (in a box-like form, or, really, the absence thereof) in the cement to place another pole in, then cement in place at the bottom, nail it in place at the top, and secure it to the closest existing pole. Other ideas discarded include a "batten" door made of wood which is less secure than a regular door (you can't put the lock mechanism inside the door because it's too thin), and a sliding door, also eliminated for security reasons.

posted by user92371 to Home & Garden (8 answers total)
I would: Measure and cut some weather-treated 2x stock (width depending on depth of wall) to fit across the bottom of the opening. Drill holes at appropriate points for securing bolts, but don't drill quite all the way through the board. Then borrow/rent a hammer drill and some masonry bits (don't bother trying this with a regular drill), and pick up some lag bolt anchors (ask the hardware store guy, or read the package, to get the right kind for old cement) and lag bolts of the appropriate size. Put board in place and drill through the holes into the cement. Remove board, tap in the bolt anchors, replace board, and bolt'er down.

Then I would frame in a new opening for a prehung metal door (get dimensions for opening from instructions that come with the door), and install said door. Get one with a deadbolt hole and hardware if you're concerned about security.

That's the easy way, and the downside is that it will leave you with a slightly raised threshold. If that's going to be a problem, or if your existing opening is too short to allow for that, you can adapt this procedure. Make your bottom board, as described above, just wide enough to cover the "non-door" space, minus 1 1/2 " for a 2x vertical. Fasten down the board. The bottom of the vertical for the side of the new door opening can then be nailed to the end of this board. Frame in as necessary. Then use the method described above to fasten the bottom of the pre-hung doorframe directly to the cement floor (instead of to the top of a 2x threshold).
posted by bricoleur at 5:10 AM on March 21, 2005

How much narrower will the new door be? Can you just build a new frame inside the old one? Rather than chiseling out a hole in the concrete you could add a bottom frame. Rent a powdered-actuated nailer from your local Home Depot or perhaps get a concrete drill-bit and screws to attach the wood to the concrete. I would use pressure-treated wood, at least for the bottom frame.
posted by bondcliff at 5:15 AM on March 21, 2005

Or just buy a pre-framed new door and rough in the wall to the new dimensions before installation.
posted by jeanmari at 6:40 AM on March 21, 2005

ditto. Is there any specific reason you haven't mentioned that you think you need to change the existing structure to put in a smaller door?
posted by winston at 7:30 AM on March 21, 2005

The existing door space is about four feet wide by seven feet. The new door will be a little under three feet wide by about six foot five. I think one of the reasons he went with the wacky open sesame door was that he didn't want to have anything on the floor (it's one continuous level sheet of cement, inside and out about eight feet in every direction) -- it's real sexy not to have to step/trip over something when you're haulling things in and out of the shed many times a day. It's of a substantial size, and half of it is devoted to a workshop -- this is an active space, not just somewhere to throw bikes and paint. Does having a bottom frame that isn't attached to the cement in any way add to security? Or is it 100% to keep the door in frame, keep out the cold (a non-issue here)? Eliminating the need for a bottom door frame would be choice, and I could fill in the rest per bricoleur's fine suggestions.

Just roughing in the wall is not an option, I forgot to mention I considered that -- I wanted something that was anchored to the floor, at least for the extra space that's to be filled in. The shed is corrugated steel on a sparse frame. Anything roughed in would probably be the weak point of the structure, security-wise.
posted by user92371 at 7:51 AM on March 21, 2005

Given your description of the use of the space I would recommend a 3 foot exterior door. Three feet is a standard size for exterior doors, meets ada specs and makes it generally easier to move people and stuff ( stoves, fridges, small boats, bulky desks, pianos, heavy cardboard boxes, stretchers.) in and out. You can find that size instock at lumber yards too, no need to special order. You will need a minimum of a 38 1/2 inch rough opening to fit a standard wood framed door. That means you need to make the opening 9 1/2 inches smaller, given a existing 48 inch opening. I would nail three layers of standard 2x framing lumber (2xx4, 2x6, 2x8 whatever is appropriate.) to the either sides of the the existing opening. This will bring the opening to within 1/2 inch of the standard (1.5" x 4 = 4.5" x 2 = 9")rough opening size which is usually fine and not a problem. If you need to adjust the width of the opening to make it smaller or larger add layers of 1/4, 1/2, 3/4 inch plywood. I would suggest picking out the door you are going to use before reducing the size of the existing door opening, this way you can measure the actual door frame and be sure you are making the opening the correct size. If you worried about decay use pressure treated lumber or keep the added framing .5 inch above the cement. good luck.
posted by flummox at 11:35 AM on March 21, 2005

Prehung doors come with a threshold as part of the frame. However, you could saw that out once you've installed the door (I'd leave it attached 'til the door is installed because it helps keep things square and plumb during that process). Assuming you've securely fastened the infill lumber (per flummox), you won't be giving up any security. You will, however, have to figure out how to keep the weather from coming in under the door. Without a threshold, nothing will be 100% effective, but a brush-style weatherstrip should keep out wind and windblown crap.
posted by bricoleur at 11:52 AM on March 21, 2005

Flummox has the right approach; his way will give you a very strong frame. If you're concerned about attaching to the cement floor, lag the sill-plate of the door to the floor. You can do this with a hammer drill and lags, or a shot hammer (ramset). You can rent a hammer drill or buy a ramset for about the same price.
posted by bonehead at 12:11 PM on March 21, 2005

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