Modify twin bedframe into full/double?
December 24, 2007 4:39 PM   Subscribe

How can I cheaply turn a twin bed frame, box spring and mattress into a full/double frame? (The current frame and mattress can't be disassembled or moved to a different room, so I need to expand/modify the twin frame + box spring so it supports a double mattress, then just store the twin mattress underneath it on the floor and bring in a double mattress for the top.)
posted by lorimer to Home & Garden (5 answers total)
Is the twin frame of the angle iron variety supported by either a pair of legs on each side or by the head/foot boards?

If so here's what I would do:

Cut 4 8' 2X4's to length so they just fit between the two side rails. A twin is ~39" wide so you'll get two cross pieces from each 2X4 with a 18" piece left over. Evenly distribute these pieces standing on their narrow sides from head to foot with the exception of two placed next to each other at 37.5". Screw those two together every 6" or so (a 8X2 1/2 screw size is about right).

Cut the left over 18" pieces to 10.5". Use these piece and cross bracing along the rails and between the top two and bottom two cross braces. Screw the cross pieces to the cross braces with the 2 1/2" screws.

A double is 54" wide which is awkward for the next step. Cut two sheets of 1/2" plywood 54"long and 37.5" wide. If you lack the equipment to rip a sheet of plywood the lumber yard will do it for you. Usually the first cut is free and each additional is 0.50-$1. Getting the lumber yard to cut them makes them easier to transport too.

Place the plywood pieces over the 2X4s butting the 54" edges together over the doubled 2X4. Screw the plywood to the 2X4s allowing 7 1/2" to hang over each side. A 1 1/4" or 1 1/2" deck screw would be about right again with a screw every 6-8" on each 2X4.

Viola. You've converted your twin into a hybrid platform bed. The plywood supports your mattress (box springs aren't really required), the 2X4s support the plywood, the cross bracing prevents the cross pieces from twisting off their edges. Test out sitting on the edge, depending on your bed's specific geometry you may need to secure your platform to the frame to prevent it from tipping. Glue could be applied between the 2X4s and the plywood if you experience squeaking.

PS: You can get away with 1X4s for your cross pieces but they are a lot harder to hit with a blind screw and you have a greater risk of splitting unless you predrill each hole.
posted by Mitheral at 6:14 PM on December 24, 2007

Response by poster: That is an awesome answer, thank you for taking the time! I would also be grateful to hear any ideas that are less construction intensive, if anybody has them?

For example, I was wondering about buying a premade flat thing like Ikea bed-slats and lashing that onto the twin frame with a constant wrap of wire (through the slats and the frame). And if that would be too likely to tip over, adding crates of the appropriate height underneath the corners of the bed-slats?
posted by lorimer at 6:49 PM on December 24, 2007

Last time I bought a frame (2003 or so) they only cost around US$35 at Costco. Why not just throw out the frame and box spring you have, buy a proper one for a full size bed, and use slats in place of a box spring, if really needed?
posted by c0nsumer at 10:48 PM on December 24, 2007

Response by poster: The twin frame and mattress have to stay inside the room (I'm renting this room in another person's apt).
posted by lorimer at 10:51 PM on December 24, 2007

What you should try to do is build a short platform/table that is the same width as the difference between the two mattresses and the same height as the frame/boxspring combo. stick this in between the bed and the wall and throw your mattress on top.
posted by davey_darling at 6:33 AM on December 25, 2007

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