loft bed design questions

[Scott Winners]

If your Doug Fir has on the mill mark or mill stamp the characters "s-GRN" is was surfaced green. Western Wood Products Association (WWPA) specifies such a label can only be applied to Doug Fir "under 20% moisture content." My experience with s-GRN DF suggests the moisture content when my sticks are surfaced is typically somewhere between 19.9 and 19.99 percent.

There are multiple agencies providing mill stamp certifications for SYP. To interpret the mill mark you would need a picture of the entire mill mark to figure out which agency issued the stamp, and then look up the spec for whatever else is in the mill mark on that agency's website. The SEMA (South East lumber Manufacturers Association) grading guide is/was available online as a .pdf, so I didn't buy a paper copy. I have zero hands on experience with SYP, but on paper it is very much like Doug Fir, the best of the regional softwoods for strength and so on. Neither one of SYP or DF are hickory or white oak, but they are both plenty stout, plentiful and inexpensive.

4x4 posts from either will be more than adequate post strength for a loft bed. Bracing against wracking and eventual failure is the more important problem.

[Matt Hunstiger]

So I've been thinking about the feedback and taught myself some sketchup to make a mock up. Right now the top of the posts and the top rails are at 84", which may change as I talk to my kids about what they want (lower). Note that although I'm talking nominal board sizes, in sketchup I did use 0.75" x 1.5" for a 1x2, 0.75" x 5.5" for a 1x6, 1.5" x 3.5" for a 2x4, and the 4x4 posts are 3.5" x 3.5". Other than the plywood, the only thing I'm using is 1x2s, 1x6s, 2x4s, and 4x4s. I found a lumber dealer (Bliffert) where I can get SYP 4x4s without having to buy them sight unseen, unlike Menards. Everything will be SYP except for the plywood, and the ladder rungs, which I will use a hardwood.

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I included a 10" tall mattress in white for reference. The lower stabilizing boards are 1x6s that are diagonals to prevent racking. They will be overlapping the posts and double-bolted to them. I just arbitrarily chose 2' and 3' heights for where the diagonals would intersect the posts, but if flatter or steeper diagonals is better, let me know.

The interior box which the mattress sits in is 76.5" x 55", and the plywood pieces are 76 3/8" x 32" and 76 3/8" x 22 7/8", which I can get from 3 pieces of 1/2 plywood (for two beds).

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Under the plywood I have eight 1x2 slats, four on either side of a central 2x4, which will have a rabbet cut out of each end so it rests on top of the cleats and is flush with the other 1x2s. Under the seam between the plywood sheets along the long axis will be another 2x4, which will overlap the shorter 2x4 through a 0.75x3.5" dado cut through the shorter 2x4.

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As can be seen, the but end of the longer 2x4 abuts the end cleats. I was thinking of joining them with Kreg pocket screws, placing the pocket holes on the top side of the longer 2x4's ends. I am open to other suggestions if this is a bad idea.

For strength I have changed the original idea of the cleats just hanging off the interior/bottom of the 1x6s with glue/fasteners to having recesses/shoulders cut into the 4x4 posts, so that the cleats have something to sit on over the posts (in addition to being fastened to the 1x6s with glue/screws).

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So the long-side 1x6s abut the posts on the ends, but the long-side cleats rest on shoulders cut into all the posts. The short-side 1x6s will sit on the shoulders just on the very ends. The short-side cleats do not sit on top of the posts, as I wasn't sure of the utility of 0.75" of the ends having something to rest on. Happy to be informed I'm wrong.

Here is a view with the 1x6 removed on the short side.

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The left side post of the ladder is a little funky because I have the 1x6 going through to the far right post, and room for the cleat to sit on a shoulder, and on the front side of the post there are recesses for the 2x4 ladder rungs. Here is a close-up with the 1x6 removed.

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The horizontal 1x6s will be attached to the posts with hardware from Rockler. The diagonal 1x6s will be bolted. I was just going to put the hardware on the outside on the long-side 1x6s so that the interior of the post and 1x6 surfaces are flush.

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Comments, suggestions welcome.

Matt

[Jamie Buxton]

Kids won't mind climbing up into bed. But who's going to be changing the sheets? How does that person feel about this bed?

[Matt Hunstiger]

That's a good question. That would mostly be me. The lofts will be in a corner of each room, so my plan is to use the top two end rails that come off to slide the mattress out a few inches to aid in changing linens. Right now the under-head clearance is about 5'. The goal is to be able to sit under there with a desk. So right now my 10yo is about 4'7" tall, which of course gives plenty of clearance for standing and sitting. I'm about 5'9", and sitting at the dining room table my head would still have room at about 4'6". He might of course be taller than I am. Anyway, I could bump the setup down 6"s. I can also build it with lower posts now, and redo it when they are older with taller posts. I should set up something to see what changing the sheets would be like for this bed. "oh, what fresh hell is this?"

[Gary Ragatz]

Matt,

I hate to be a naysayer, but I don't think you can achieve what you're trying to, when you're working with an 8' ceiling. 24" mattress-to-ceiling clearance is probably okay for your 10yo. It's going to be a PITA for you changing linens. And your plan seems to be to make that clearance tighter as the kids get bigger.

My suggestion is to size the loft for a 36" mattress-to-ceiling clearance. This should give you comfortable sleeping space as the boys grow and reasonable clearance for you to change linens. This isn't going to allow enough space to sit at a desk under the bed, so you need to rethink how to use that space. If you don't like the idea of a roll-out desk, here are some other possibilities:

(1) If you really want the kids to spend time under the bed, put in a couple of beanbag-type chairs so they can lounge there. Also good enough if they're using a laptop or Chromebook for school work. Get them each a lap desk, in case they need a writing surface. Build in some shelves or cubbies for storage, some decent lighting, and they have a nice lounging/workspace. With a 50" clearance under the bed, this might work for them through high school.

(2) If you really think they need a desk, build a fixed worktop into the loft frame. Kid sits outside the footprint of the bed, so head clearance is not an issue. Chair slides under the worktop when not in use, so it uses up almost no floor space. You could put in some task-lighting under the bed frame.

(3) If the boys use a chest of drawers for clothing storage, maybe that could go under the loft, and the freed-up space could be used for a desk.

So, I've beaten this drum twice now, and I'll shut up.

[Matt Hunstiger]

Gary,

I do not regret these comments at all. Nothing has been purchased, and nothing written in stone. Since my longer update with Sketchup the other day I have bumped the height down half a foot in my model, which puts the post tops at 78", leaves ~28" between the ceiling an the mattress top, and has ~4' 6" under the frame clearance. My son is sleeping so I will measure his dresser tomorrow to see how tall it is. I know my daughter's dresser would fit under a shorter setup. Actually now that I think about it I kind of like the idea of a desk that is attached to the frame, but swings up out of the way. I just rewatched a bit from Ask this Old House where Tom Silva helped a woodworker build a wood shop in her 1 car garage, and they made a bench that hangs from the wall on a hinge with legs that fold out ("How to Set Up a Garage Workshop | Ask This Old House"). So here's just a quick rectangle in sketchup without any real frame showing a desk surface that could be attached to the short end. I like this idea.

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[Gary Ragatz]

Matt,

I think the fold-down desk idea has a lot of potential. Wouldn't be practical to put drawers in the desk, but if you wanted some storage, you could attach some shelves/cubbies/whatever to the posts, so they're hidden when the desk is folded up, but accessible when it's folded down - kind of like what you might see at the back of a roll-top desk.