I am planning bunk beds which do not extend to the floor, but, instead, are supported by brackets fastened to the wall. Calling them cantilevered may be incorrect. Hopefully, the image that I have included says it all.
Now, the part that I do not know how to “engineer” is proper load bearing. Three brackets should be enough (I think) for a twin size bed. Where would one go in order to find out how to properly size the brackets?
Thanks and regards,
Todd
Replies
The brackets will not only have to support the total vertical load of the "inhabitants", but also the maximum torque generated when there are point loads near the unsupported end of the bed -- not to mention any dynamic loads.
For example assume a 100# occupant sitting at a point 6 ft from the attached end of the bed. The brackets and structure then must resist a 600 ftt-lb torque effectively applied right at the junction of the wall & the bed rail. If that occupant likes to bounce around a little bit, the loads will be a lot higher.
For Children, but still...
Thanks for your comment bd! You provided the kind of structural insight that I desperately need.
I don't know if this image changes some of the load concerns, but I was thinking about reinforcing the plane of the wall with slats. In my mind, the brackets are only as strong as the 2x4 wall partitions + the multiple instances of 1x3's. I'm pretty sure that I could over-engineer the supports,... but you know that I'm not working from a place of knowledge about the real stresses a "bunk bed" like this would truly need.
The brackets will be a significant hazard to the occupant below.
Two boys, both want top bunk
Thanks DanH!
In hindsight, I probably should have referred to the bed(s) as loft beds. I have two boys who both want the top bunk, soooooo,.... I'm in need of structural advice for how to properly build safe and attractive bunk/loft/cantilevered/bracketed beds on either side of a bedroom. Where does one go to obtain this kind of help? If it is simpler to just over-build, then I can go that route. I'm not using metal, but these do what is required and hold an amazing amount of weight:
Maybe you should be using metal.
Good Input
Thanks again DanH. You're giving me some good ideas. So as to provide better support, what if I secured one end to the adjoining wall, so that there is support along one long side and one short side, *and* support the other short end with a ladder? I don't see how I would max out the tensile strength of even a 2x4, but I can certainly see what you're saying about the connections *to* the 2x4's. Also, I accepted that the bed-wall-bracket would describe a 4-foot triangle, creating a substantial "foot" for the diagonal brace.
it can definitely be done
but you need a total solution because of the likely occurrence of concentrated loads as Dan pointed out. Not only do you need to worry about the brackets and wall attachment, but the wall structure itself.
If you're willing to put forth the effort to construct the beds properly, I'd suggest seeing a local engineer. It shouldn't cost too much to get some detailed design help on something like that. If you're lucky, you might find someone that'd do it just for grins or a minimal fee since it would most likely not require a PE's stamp. A lot easier to sit and talk about it over a cup of coffee & flesh out the details, e.g., how big are the kids? how long are you planning on using? etc. With a little design help, it'd probably be possible to fabricate some metal brackets that would support the beds and also provide adequate bracing to the wall structure.
of course
Thanks for the comments
I know a lot of home building and remodeling involves ensuring that a structure is supported all the way down to the foundation, so I appreciate the cautionary comments. They're meant out of concern for safety, and that's not lost on me.
Honestly, I didn't even know that structural engineering was its own discipline. Just from observation, however, I've seen closet shelves supported by simple brackets carry *a lot* of weight. I've seen them collapse, too, so I want adequately built bed bracket supports.
I do want the supports to look like furniture, and not necessarily something fabricated for a factory. I'll definitely consult a structural engineer, however. I often ask myself, "what would MacGyver do?",… but I'm pretty sure even he couldn't pull this off with just a paper clip and duct tape.
Is this really a good idea?
I often tell the DW that just because something sounds like a good idea, that does not mean that it will actually work. I can't help but wonder if your bed design is an example of this.
I was at Talesign (sp?), Frank Lloyd Wright's Wisconsin home, where he had a cantilevered balcony. They found that when a one person walked to the far end of the cantilever, the base of the cantilever moved over a foot! The other posters are not kidding when they talk about the actual load created and the possibilty of bowing a wall.
Good luck.
"lofty" ideas
It's funny how I thought of FLW's cantilevered inventions, especially the piano "hidden" inside a stairway at his home and studio in Oak Park, IL and the generous platforms of House on Fallingwater when envisioning my loft beds.
Ideally, I would sister a metal beam beside a 2x4, and secure it to the header and footer of the wall, and bolt the brackets to the beams. I haven't decided how much I want to tear into the walls before I just go with two conventional platform beds for the kids.
I don't think I'm even talking about a cantilever anymore if I secure the foot of the bed to the adjacent wall of the long side, and then support the other short side with a ladder.
Reference images
These two photos show a little bit of what I am trying to accomplish, albeit as free-standing units. The first image appears to show a support cord extending up to the ceiling, and may simply be representative of a "suspended" bed.
The second image appears to be metal, but the supports are very simple. An unattractive solution to my eyes, but still...