Locating failure points on a flimsy bed
April 13, 2025 8:00 AM Subscribe
The IKEA MYDAL pine bunk bed is rated for 200lbs max. Suppose one wanted to build it as a loft, but also reinforce to safely hold much more weight on the top bed. How would one identify the weak points needing to be reinforced?
Past a certain point it's easier to just build something from scratch, but cheap lumber these days is pretty twisty and unpleasant to work with, so there's a certain allure to the idea of starting from a nice straight base and just adding Frankenmembers to reinforce things as needed.
The bed could be bolted into wall studs to secure it, which presumably would help a lot. Past that, is there a way to tell whether "200 lbs max" means "uprights will shatter into sawdust at 201 lbs," or just "we cheaped out on aluminum fasteners" or "needs a crossbar right here but that wouldn't fit in the flat pack," or what?
Past a certain point it's easier to just build something from scratch, but cheap lumber these days is pretty twisty and unpleasant to work with, so there's a certain allure to the idea of starting from a nice straight base and just adding Frankenmembers to reinforce things as needed.
The bed could be bolted into wall studs to secure it, which presumably would help a lot. Past that, is there a way to tell whether "200 lbs max" means "uprights will shatter into sawdust at 201 lbs," or just "we cheaped out on aluminum fasteners" or "needs a crossbar right here but that wouldn't fit in the flat pack," or what?
I can’t answer your question directly, but the assembly instructions PDF (which you may have already seen) illustrate that the bed is held together with 222 pegs and screws rather than larger metal braces or brackets. There is probably a way to reinforce those connections — like adding wood glue into the hole into which one is to place a wood peg before inserting it — to achieve a stronger result than the design specifications.
Alternately, could you visit an IKEA and have a look at a built model on the showroom floor and give it a shake to see how stable it feels?
posted by mdonley at 8:27 AM on April 13
Alternately, could you visit an IKEA and have a look at a built model on the showroom floor and give it a shake to see how stable it feels?
posted by mdonley at 8:27 AM on April 13
Those uprights are very thin. If you don't want to start from scratch, I bought a bed from this company. It seems quite sturdy, and I have put over 300 lbs on it without noticing any weakness. You could ask them about weight limits.
Assembly was significantly more work than Ikea, but no problem for a single person to do.
posted by novalis_dt at 8:30 AM on April 13 [3 favorites]
Assembly was significantly more work than Ikea, but no problem for a single person to do.
posted by novalis_dt at 8:30 AM on April 13 [3 favorites]
Note that the 200 lbs is for 'static load', so sitting or lying down. If you are crawling over the bed to get from one end to the other, you're putting the load on a smaller number of slats and they may crack. (I have evidence.)
By the way, KURA might be a better fit for your needs, since it only has one bed base.
Either of these are sold as kids' beds and do seem to have been engineered as such. If you'll need this to hold a full-grown adult (perhaps even two, on occasion?), I'd count on reinforcing basically everything. IKEA is pretty good at engineering, after all, and cost-effectiveness is part of their requirements.
posted by demi-octopus at 8:34 AM on April 13 [1 favorite]
By the way, KURA might be a better fit for your needs, since it only has one bed base.
Either of these are sold as kids' beds and do seem to have been engineered as such. If you'll need this to hold a full-grown adult (perhaps even two, on occasion?), I'd count on reinforcing basically everything. IKEA is pretty good at engineering, after all, and cost-effectiveness is part of their requirements.
posted by demi-octopus at 8:34 AM on April 13 [1 favorite]
Structurally, it goes like this for someone on the top bunk: person sits on mattress; mattress sits on slats; slats rest on a piece of wood along the sides; that piece of wood is attached to side rails (IKEA-installed with screws); side rails attach to verticals with pretty standard IKEA peg/bolt combo; verticals go to floor.
In that whole load transfer system, I think the first failure point would be the connection between the side rails and the verticals, and by extension the lateral stability of the whole thing once put up. I have a lot of experience with IKEA beds and I generally have confidence in the load-bearing capabilities of their peg/bolt combo and I like that the bolts they use are relying on the metal rather than being wood screws resisting pullout. But with this kind of thing, I don't think it offers a lot of resistance to wracking - like if there's a kid on the top bunk moving back and forth, what really prevents the whole thing from going from right angles to parallelograms (and further) really quick? The whole thing is kind of similar to the HEJNE shelving unit (formerly GORM), where you need to put a x-brace on the back to prevent wracking every so often, but this has no such requirement. All resistance to wracking is in the depth of the wood members between bolts - exert enough force to blow out that dimension of wood and the frame acts like a domino set.
Secondary concern for me would be member size of the side rails, then size of the verticals. Side rails would fail with too much weight, probably mid-span from bending stress; hard to guess what that weight limit would be. Verticals would probably fail from buckling between the lower and upper bunks - how much weight it would take to bow out a vertical enough to cause a problem is a question, but if you have 4 verticals splitting the load that seems like less of a concern to me than the two side rails.
posted by LionIndex at 8:58 AM on April 13 [2 favorites]
In that whole load transfer system, I think the first failure point would be the connection between the side rails and the verticals, and by extension the lateral stability of the whole thing once put up. I have a lot of experience with IKEA beds and I generally have confidence in the load-bearing capabilities of their peg/bolt combo and I like that the bolts they use are relying on the metal rather than being wood screws resisting pullout. But with this kind of thing, I don't think it offers a lot of resistance to wracking - like if there's a kid on the top bunk moving back and forth, what really prevents the whole thing from going from right angles to parallelograms (and further) really quick? The whole thing is kind of similar to the HEJNE shelving unit (formerly GORM), where you need to put a x-brace on the back to prevent wracking every so often, but this has no such requirement. All resistance to wracking is in the depth of the wood members between bolts - exert enough force to blow out that dimension of wood and the frame acts like a domino set.
Secondary concern for me would be member size of the side rails, then size of the verticals. Side rails would fail with too much weight, probably mid-span from bending stress; hard to guess what that weight limit would be. Verticals would probably fail from buckling between the lower and upper bunks - how much weight it would take to bow out a vertical enough to cause a problem is a question, but if you have 4 verticals splitting the load that seems like less of a concern to me than the two side rails.
posted by LionIndex at 8:58 AM on April 13 [2 favorites]
From general experience with this type of bed rather than the IKEA one specifically the modification I'd make would be a 2x4 on edge length wise down the middle under the slats. Then I'd extend a 1x4 from the 2x4 all the way to the ground. If it wasn't being bolted to the wall I'd run a diagonal 1x4 from top to bottom on both ends and a 1x4 cross brace from top to bottom on the back.
posted by Mitheral at 9:22 AM on April 13
posted by Mitheral at 9:22 AM on April 13
3/4 inch plywood on the outside of the front and back, with a generous number of 1 1/2 in GRK screws, would get you a long ways at the cost of asthetics and easy take down. Adding more plywood along the sides would ado even more stability. If you glued the plywood on with construction adhesive, all the better!
I don’t know what the under the mattress slats look like, but you could replace them with slats from a burlier IKEA twin bed or 1x2s
posted by rockindata at 9:29 AM on April 13
I don’t know what the under the mattress slats look like, but you could replace them with slats from a burlier IKEA twin bed or 1x2s
posted by rockindata at 9:29 AM on April 13
Not sure of the advantage you see with starting with this unit.
IKEA stuff is designed to work the way it's designed. This is a bunk bed that will be sturdy as a bunk bed. If it's built to be something else, like a loft bed, it will lose some of its designed strength, which is already 200 pounds, not 300. If you have to remove parts (which I would guess you would have to do to make it be a loft), it will fail unless you fully redesign it, at which point you would be better off starting from scratch or getting the thing novalis_dt linked to. Does it cost more? It does. It costs less than whatever it will cost you when a hacked bunk bed collapses.
Signed, someone who destroyed a Kallax by removing one 1.5cm shelf.
posted by sageleaf at 9:54 AM on April 13 [3 favorites]
IKEA stuff is designed to work the way it's designed. This is a bunk bed that will be sturdy as a bunk bed. If it's built to be something else, like a loft bed, it will lose some of its designed strength, which is already 200 pounds, not 300. If you have to remove parts (which I would guess you would have to do to make it be a loft), it will fail unless you fully redesign it, at which point you would be better off starting from scratch or getting the thing novalis_dt linked to. Does it cost more? It does. It costs less than whatever it will cost you when a hacked bunk bed collapses.
Signed, someone who destroyed a Kallax by removing one 1.5cm shelf.
posted by sageleaf at 9:54 AM on April 13 [3 favorites]
Suppose one wanted to build it as a loft
If by build it as a loft you mean without the bottom bed, I would assume it will already be less strong with one or two of the rails for the bottom bed frame missing. This would make it easier for the frame to twist and fail due to sideways loading on the posts, which are very thin. The bottom long rail is needed to support the ladder anyways.
For that reason, I think you'd be better off building something sturdy out of dimensional lumber rather than weakening this bunk bed by converting it to a loft and then trying to strengthen it.
posted by ssg at 9:56 AM on April 13 [1 favorite]
If by build it as a loft you mean without the bottom bed, I would assume it will already be less strong with one or two of the rails for the bottom bed frame missing. This would make it easier for the frame to twist and fail due to sideways loading on the posts, which are very thin. The bottom long rail is needed to support the ladder anyways.
For that reason, I think you'd be better off building something sturdy out of dimensional lumber rather than weakening this bunk bed by converting it to a loft and then trying to strengthen it.
posted by ssg at 9:56 AM on April 13 [1 favorite]
I guess speaking as a grandfather, I’d ask what your level of concern about the occupants is? If the level is “child” or “grandchild,” no way I’d try to outguess IKEA’s offices full of mechanical engineers (and I agree with another poster, those uprights are seriously thin)—I’d build one from scratch where I knew it was seriously over-strong.
As for the nastiness of big-box lumber, I agree. There is probably a real lumberyard in your area serving professionals who build furniture and things. Find it and go there and ask the yard guy to suggest what he’d use if he were building a lofted bed. Stress the importance of expense. You might be surprised, and a few hours at a real lumberyard is like fishing: not counted towards your eventual lifespan.
Good luck with whatever approach you take.
posted by Gilgamesh's Chauffeur at 9:58 AM on April 13 [8 favorites]
As for the nastiness of big-box lumber, I agree. There is probably a real lumberyard in your area serving professionals who build furniture and things. Find it and go there and ask the yard guy to suggest what he’d use if he were building a lofted bed. Stress the importance of expense. You might be surprised, and a few hours at a real lumberyard is like fishing: not counted towards your eventual lifespan.
Good luck with whatever approach you take.
posted by Gilgamesh's Chauffeur at 9:58 AM on April 13 [8 favorites]
Oh, I should have said: if you say what area you live in I’m sure folks could suggest a good place to get real lumber. They don’t usually advertise much because the people that need them know through word of mouth…
posted by Gilgamesh's Chauffeur at 10:00 AM on April 13
posted by Gilgamesh's Chauffeur at 10:00 AM on April 13
When I was young we had a bunk bed and I don’t know the details whether there were just not enough slats or ill fitting slats but my friend climbed the ladder and flopped down on the top bunk and the whole mattress fell down onto the lower. Thankfully nobody was down there.
The first thing I would do would be to get a solid beam that runs lengthwise and put a big bolt in to anchor it into the center of the head and foot boards and then probably nail the slats into the top of that.
That’s my unequcated opinion of what the most likely failure mechanism would be.
If you’re going to reinforce the vertical beams you probably should just start with a sturdier bed but it also can’t hurt to reinforce the corners as well.
posted by cali59 at 10:05 AM on April 13
The first thing I would do would be to get a solid beam that runs lengthwise and put a big bolt in to anchor it into the center of the head and foot boards and then probably nail the slats into the top of that.
That’s my unequcated opinion of what the most likely failure mechanism would be.
If you’re going to reinforce the vertical beams you probably should just start with a sturdier bed but it also can’t hurt to reinforce the corners as well.
posted by cali59 at 10:05 AM on April 13
Do not overload this bed. It's not designed for adults. Find a better designed bed.
Unlike most IKEA bedframes, the slats on this one are not arched plywood, they're flat. Arched slats can take a lot more load than flat ones.
For what it is worth, we bought the steel framed IKEA loft bed VITVAL, and it uses the arched slats and can handle an adult human easily. It's very sturdy when assembled correctly -- but you only get one sleeping surface.
posted by seanmpuckett at 2:58 PM on April 13
Unlike most IKEA bedframes, the slats on this one are not arched plywood, they're flat. Arched slats can take a lot more load than flat ones.
For what it is worth, we bought the steel framed IKEA loft bed VITVAL, and it uses the arched slats and can handle an adult human easily. It's very sturdy when assembled correctly -- but you only get one sleeping surface.
posted by seanmpuckett at 2:58 PM on April 13
If by 'build it as a loft' you mean 'build it with the top bunk only, leaving space for a desk or whatever underneath', I think that would not be too difficult. What you would be replacing is the torsional reinforcement of the bottom bunk and that can be done relatively easily by adequately fixing the whole frame to the two walls it is adjacent to (I don't think fixing to one wall would be enough). Taking out the bottom bunk doesn't change the load on the uprights much, if at all but you would have to extend the upright to the right of the ladder and fix that and the other corner where the ladder is to the floor. I would leave any of the bottom side rails on where they aren't in the way and fix anything that touches the wall securely to the wall.
But if you want to make something that takes more weight, the effort and cost would be way more than making or buying something designed for that. As others have said, Ikea engineering is very precise and if there was a way to make the unit cheaper by using less or less strong material, Ikea would have done so. 200lb is only 90kg, which is barely enough to hold an averagely active child. I don't recommend this and the material and work to bring the bed up to this task would be far more than buying something designed for the purpose.
posted by dg at 4:59 PM on April 13 [1 favorite]
But if you want to make something that takes more weight, the effort and cost would be way more than making or buying something designed for that. As others have said, Ikea engineering is very precise and if there was a way to make the unit cheaper by using less or less strong material, Ikea would have done so. 200lb is only 90kg, which is barely enough to hold an averagely active child. I don't recommend this and the material and work to bring the bed up to this task would be far more than buying something designed for the purpose.
posted by dg at 4:59 PM on April 13 [1 favorite]
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Assuming this is actual pine and not "pine" I would reinforce every 90 degree angle with a diagonal brace or bracket and double up the longest horizontal and vertical pieces. But by then I'd have almost built this from scratch so I might just do that instead.
posted by zippy at 8:20 AM on April 13 [1 favorite]