King size mattress on top of two twin size box springs?
March 27, 2019 8:01 PM   Subscribe

Can we temporarily put a new memory foam king size mattress on top of two twin size box springs?

We have been sleeping on two twin size mattresses pushed together for a few years, and we are ready to buy a king mattress. We plan to build a king size platform for the new king mattress, but it will realistically take us 1-2 months to get it all finished.

Are we okay to lay the king size mattress on top of the twin box springs for a couple months, even though the mattress will be 5 inches longer than the box springs?
posted by allison00 to Home & Garden (11 answers total)
 
I don't see why not. I'd connect the box springs together even if they're just sitting on the floor. Maybe wrap them edgewise with some colorful climbing rope.
posted by Marky at 8:30 PM on March 27, 2019


My king mattress actually sits on two twin box springs. They don't overlap each other, but I don't see the harm in that. You could also position the box springs with one higher and one lower than the other, and the mattress will meet up in two corners.
posted by JoeZydeco at 8:35 PM on March 27, 2019 [3 favorites]


Yes, king box springs are often split because otherwise they’d be very hard to move, lacking flexibility. If you care about the mattress warranty, having the mattress be longer than the box springs could void that warranty.
posted by Knowyournuts at 9:08 PM on March 27, 2019 [4 favorites]


My king mattress sits on two twin boxes. Has for over 2 decades. It is the way we purchased it originally from the store.
posted by AugustWest at 11:11 PM on March 27, 2019 [1 favorite]


Yes. I did this in college when my dorm-mate's student visa was denied last minute and I had a double room all to myself for the year. It was amazing. I wasn't even using box springs as the base, just dorm-quality twin mattresses, and it worked like a charm. Best sleep I had in college, hands down.
posted by saladin at 3:55 AM on March 28, 2019


Most king sized box springs are in two pieces for weight and maneuverability reasons.
posted by soelo at 10:19 AM on March 28, 2019


If you are worried about the bend of your longer than the box spring mattress a chunk of plywood (say 24" wide) placed at the end of the bed between the mattress and box springs and sticking pass the box springs the amount of the overhang will support the mattress as long as you don't sit on it or something of that nature.
posted by Mitheral at 12:32 PM on March 28, 2019


"chunk of plywood (say 24" wide) placed at the end of the bed between the mattress and box springs"

A word of caution: I used plywood under my mattress for a few years and ended up with a mattress I couldn't flip over because of splinters.
posted by komara at 2:20 PM on March 28, 2019


Yeah, 5 inches is 2.5 on top and 2.5 on the bottom. I would just center the mattress over the box springs and not sit on the end.
posted by soelo at 2:59 PM on March 28, 2019 [4 favorites]


Hi, mattress retailer here. The standard foundation for a US King size (appx 76" x 80") is two Twin XL box springs (each 38" x 80"). A standard Twin is 38" x 75", so yeah, you'll be short. If your mattress is 100% memory foam, it might be okay for a while, but you still risk permanent damage. Most memory foam mattresses are made up of several different layers of foam, glued (laminated) together. The mattress will want to curl over the unsupported overhang, and could cause the layers to delaminate in those areas, (especially since the short box spring will create a very sharp edge for the mattress to break over) leading to lumps or dips in the overall mattress surface, or noise from the layers flexing and rubbing against each other instead of remaining one unified piece.

If your mattress is a hybrid, with springs on the bottom and memory foam on top, you will very likely permanently damage your mattress by doing this. All-foam mattresses are a little more forgiving, but there's a reason most brands say to limit bending the mattress to no more than 30 degrees; you can "break its back" and it'll never be the same.

When we were brand new to the mattress biz 3 years ago, we permanently ruined an all-foam mattress, and an innerspring mattress by sharply bending them trying to navigate the interior of a yacht during delivery. If you need to get the King mattress before you have the platform ready, I would just put the King on the floor so that its underside is fully supported, edge to edge. Or just wait until your platform is ready.
posted by xedrik at 10:11 AM on March 30, 2019 [1 favorite]


Response by poster: We decided to buy a frame online for $90 so that we didn't damage the mattress. We are going to wait to build the platform. Thank you for all of the advice!
posted by allison00 at 12:30 PM on April 27, 2019


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