Can I screw into the sides of joists to hang small loads?

September 5, 2009 5:35 PM

Is there any reason to not screw hooks into the sides of joists, rather than into the bottoms? This is for 10-50lbs per joist at most.

I'm hanging bikes in the garage: exposed, unfinished ceiling; 50 year old wood, 2x12. To maximize space and to utilize the joists with conduit already attached to their undersides, I'd like to screw the hooks into the sides of the joists rather than into the bottom of the joist or into the ceiling wood. (This actually strikes me as stronger since we're now mostly dealing with tension instead of shear.)

I plan to screw into the middle 1/3rd, of course, away from any other holes and as far apart as possible from each other when there's two hooks on either side of a joist. This will be near the ends of the joists, within 12" of the concrete foundation. The maximum load will be about 20-30lbs/hook, and no more than 50lbs/joist for those with a hook on each side. This is mostly because my better half refuses to give up her 30lb commuter and join my sub-16lb stable. I'll drill pilots.

I can't get it out of my head that I'm going to eventually split the joist or something equally improbable. I figure - in the real world - the worst case is that I'll bend some hooks if I overload them, which is no big deal.

Am I crazy?

Anything else I'm forgetting would be great, of course.

posted by kcm to Home & Garden (13 answers total)

Best answer: I think you'll be fine.

I installed some eye bolts into the sides of studs in my garage wall, similar to what you're planning, just in the wall rather than the ceiling. These are for security purposes (e.g. locking up bikes and tools to make them harder to walk off with if somebody gets the door open). These bolts stick out a few inches.

I wanted to make sure they wouldn't be easily ripped out, so I tested them by trying to do just that, in the same relative direction as you'd be applying a load. They didn't budge, and that is in the middle of a 2x4 rather than a 2x12. I'm certain I applied a whole lot more than 30 lbs in that effort.
posted by FishBike at 5:50 PM on September 5, 2009

Best answer: I have bikes hanging from sideways hooks in my garage. The hooks have bent, but that's it. Mine are in studs, not joists, so the downward pressure is in no danger of splitting the wood. If you make sure yours are in the center of the joist, I don't think splitting should be any problem.
posted by The Deej at 5:51 PM on September 5, 2009

Best answer: It should be fine. The biggest risk is torsion; if you hang enough stuff on it you might eventually warp the joist. This is a long term problem, though. (A couple of decades, probably, if even that soon.) Wood is pretty strong as long as you don't subject it to sudden, sharp impacts.
posted by sonic meat machine at 5:52 PM on September 5, 2009

Anything else I'm forgetting would be great

I'm no carpenter but the physics of the hook mounted sideways results in a lever-arm that multiplies the force on the wood when weight is applied.
posted by Palamedes at 5:52 PM on September 5, 2009

Best answer: If you want to over-build, you could put pieces of 2x12 in between, and perpendicular to, the joists. Plywood spanning several joists would also increase the strength.
How do you lift the bike up to the hook ? I have hooks in the wall of the garage that hold the front tires of the bikes while the rear tires are on the floor.
posted by llc at 6:03 PM on September 5, 2009

I'm no carpenter but the physics of the hook mounted sideways results in a lever-arm that multiplies the force

By a tiny degree, since the length of the lever is only half the distance the hook juts out.

You're fine, but I like llc's idea of putting the hook(s) on even a loose piece of lumber laid across the joists instead: if it crosses a few of them, it spreads the load very very thin.
posted by rokusan at 6:46 PM on September 5, 2009

Best answer: For hanging bikes, probably no difference. The technical difference is that when you screw into the side, you're putting the steel of the hook into shear (more or less) and putting basically no force on the threads buried in the wood. When you screw into the bottom, the steel is in tension (aka, typically much stronger) and the downward weight of the bike is transferred into the threads.

Unless you ride a cast-iron bike or are using really small-gauge steel hooks, your bikes aren't heavy enough for you to have to care about the difference.
posted by range at 6:55 PM on September 5, 2009

Oh, and -- the chance of the weight of the bikes splitting the lumber is pretty slim. However, the chance of the hook itself splitting the lumber might be kind of high (depending on how big your hooks are), so don't forget to drill pilot holes that are big enough.
posted by range at 6:57 PM on September 5, 2009 [1 favorite]

Best answer: I foresee no more problem than any of the other posters do. (Credentials: my father was an architect; all my high school and college jobs were as a construction worker on his job sites. I have personally done pretty much every building trade there is except ones that require serious state licensing--e.g. master electrician, steamfitter. And I, perhaps in contrast to others who have benefited from this kind of nepotism, took these jobs damned seriously and learned as much as I possibly could. Since then I have remained "handy," as they say, and have done major additions and rehab projects to my own house and those of friends.)

Certainly nothing is going to go wrong with your structure instantly and terribly, so at the very worst you can watch the installation under load and take the bikes down if you see torsion warp happening. (As sonic meat machine suggests, seeing this will be like watching grass grow only slower.) As for the risk of merely putting a hole in the joist, a loose knot will do worse than that when it comes to graphing out the stresses and strains, and loose knots aren't at all uncommon.

> don't forget to drill pilot holes that are big enough.

Amen to that. Don't be tempted by hooks with a pointed screw end (though all the bike hooks I've ever seen have these.) Get the kind that goes all the way through the joist and is fixed in place with a washer and a nut. If you can't find ones like this that have bike hooks pre-dipped in plastic to protect your bikes' paint you can dip them yourself (you'll find cans of dipping goo in the paint department.) Or just wrap 'em in electrician's tape.
posted by jfuller at 7:15 PM on September 5, 2009

Best answer: Screwing into the side is okay, as long as you stay several inches away from the bottom or top edges.

Think about an I beam. They look that way because the forces are concentrated in the top and bottom (wik). The forces in your wooden joist follow exactly the same pattern. If you put a big hole in the part which is carrying a lot of load, you might start a crack that could propagate. Probably not going to make your ceiling fall even if you screw it up, but much better to aim for mid joist and avoid the problem entirely.

You can put a hole vertically through the load carrying part of a joist because the volume of load carrying wood affected is smaller, and the possible cracks introduced would propogate in a non load carrying direction.
posted by Chuckles at 7:22 PM on September 5, 2009

Best answer: nthing that you are fine. 50 year-old 2x12s are probably some pretty nice wood -- tight grain, few knots, probably close to their nominal dimensions (none of that 1.5x11.25 stuff). Structurally probably closer to the strength of a modern 3x14 or something.

In terms of failure modes for a threaded hook, your more likely failure mode is almost certainly withdrawal (a hook loaded in tension whose threads tear through the fibers of the wood)
rather than shear (where the hook literally needs to "cut"/crush/rotate down through the wood in order to pull out). but no, you are not going to damage the joists. staying in the middle 1/3 is a good rule-of-thumb (same as what plumbers/electricians follow when drilling for pipes + wiring), as is pre-drilling.

The fact that you are asking the questions means that you are sufficiently conservative to be just fine :)
posted by misterbrandt at 9:45 PM on September 5, 2009

Response by poster: Lots of thought all around, thanks. Back from dinner and a movie and all three are where I left them, including der großen fahrrad meiner frau. I had toyed with the idea of a through-and-through bolt of any kind as well as using lumber laid over the joists, and so I'll keep an eye out for better hooks of that sort.
posted by kcm at 10:37 PM on September 5, 2009

Best answer: Best of all would be hooks made out of flat steel strap (say 1" x 3/16"), dipped in goo or wrapped in a piece of old cycle tube to avoid scratching, and bolted hard up to the side of the joist. Virtually no torsion-producing lever arm at all. If you countersink the bolt holes in the straps and use bolts with countersunk heads, you will get hooks nice and close to the joists with no sticky-out bolt heads to scratch your bikes as you load and unload them.
posted by flabdablet at 3:33 AM on September 6, 2009 [1 favorite]