Need construction advice for huge shelf

[BarnyardChaos]

So first I'm sorry this question is totally unrelated to chickens or coop construction, but I have a conundrum and I know there are a roomful of construction experts in this forum. So may I ask for some advice, please?

I need to build a shelf. A BIG one. It's to span over a bank of refrigerator and freezers in our storage room. It cannot 'rest' on top of the appliances, obviously, but needs to be supported on the ends and edges only. It will fill the end of the room, 132" wide corner-to-corner, and 30-32" deep. I will store lightweight, bulky things on top, such as blankets and pillows, bulk toilet paper and paper towels, and empty totes and coolers - maybe 300-400 lbs. total. Of course I need to maintain air flow around the appliances as well. There's very little space to add vertical supports on each end, and doubtful if I can put a support pole in the center (I'd rather not, if possible).

I'd like to use what I have on-hand as much as possible. I have a whole pile of used 2x4's and 4x8 wood siding panels at my disposal. I'm aware I'd have to buy a couple of 12-ft long pieces of lumber for front and back edges. But I cannot find anywhere around here with 12' long plywood, and anyway that's a whole lot of weight and awkwardness to try to wrestle into place for a 63-yo woman doing it myself. I'm handy with tools and have the necessary circular saw, power drills, carpenter square, stud-finder, etc.

Here's the room:

And here are a couple of sketches of what I think it might look like:

I can rest the corners of the frame on top of 2x4's attached to the walls to help with stability, though I cannot decide if I must wrestle sections of plywood or siding up there, or if I can do it with 1x12 boards cut in the 30-inch direction. I used the "Sagulator" suggested by @saysfaa here https://woodbin.com/calcs/sagulator/ and it would be a piece of cake IF I could get my hands on a 12' long sheet of plywood, OSB or siding, AND wrestle that monster up to the shelf supports. Not happening. I could do it with one 4x8 sheet in sections (one piece 30" x 96" and two fill-in sections at each end of 30" x 18"), or better yet, planks (1x12x30", about 12 of them). But I am completely unsure if the front horizontal board could support the weight safely if the shelf material isn't all in one piece.

Advice, please?

 

[BarnyardChaos]

the shelf is DONE and ready for storage. As promised, here's some photos of the process:

The framework going up and eye bolt lag screws in place. I was surprised to find the ceiling is just lath and plaster, too - and that the joists run parallel to the shelf, not perpendicular. So by adding two screw/cable supports, at least the weight is divided and supported nearer both ends of the same joist instead of all in the middle. They are evenly spaced 45" from walls and 45" apart. If I were unsure about it (I'm not), I could add another steel cable to each one, angled back to the next joist:

I located and marked all of the studs, and used cabinet screws for extra security:

I opted to use joist hangers for the front support board, because the end supports would have had only one stud in the middle and in the back corners to support them. To make them long enough to reach the front studs, I had to put the front support board in-between them:

Cut out a piece of molding from both sides of the window:

Steel cables are in place. Marks and holes in the ceiling are to measure and be certain I was drilling into the center of the joist. I probed to find both sides of the joist, then marked the center to drill. Those eye screws are 4-1/2" long. I tightened the cables by wedging a 2x4 underneath to push the front support board up a bit. Covered the ends in duct tape to match, and voila. Shelf boards laid, and a 1x6 face board added for appearance. I left just 1/4" lip above the shelf, to prevent things rolling off but not so much that it would make it hard to pull things down:

Couple of 2x4 spacers to support the face board:

Some hole patching, primer and paint --- and it's DONE!

I forgot to patch and paint *before* installing shelf boards. Oops. Oh well, it won't be seen anyway and I can do it (with some acrobatics) later when we paint the rest of the room:

And yes, that shelf is perfectly level and plumb to the magnetic axis of the earth, if not to the ceiling and floors (both noticeably UNlevel).

And just in case you're wondering, we have another freezer for chicken, fish, wild game and other miscellaneous - against the right hand wall. That refrigerator on the left is for eggs and beverages.
Looks pretty good, if I do say so myself!

 

[Captain13]

You wouldn’t have to cut any drywall to attach the shelf to the ceiling. Suspend it with threaded rod.

 

[Captain13]

Screwing into the ceiling joists from below with an eye bolt would work with cables just fine. Use a stud finder to get in the center of the joist. You could secure the back of the shelf to the wall for stability if you wanted to.

 

[woodworm]

Agree with @Captain13

Post pic when it's done!

 

[woodworm]

I'd imagine at that span it's going to sag without a support in the middle. Ideally I think you'd add additional cross supports to help support the shelf, but that will add to the weight. Can you take a support upwards to a ceiling joist?

What are the walls made of - stud / plasterboard or brick? And is that a window behind the fridges?

 

[Captain13]

I hadn't thought of that option. It would require an attic rat (my grandson maybe) to crawl up there and nail a support board across a couple of joists, to attach the allthread to. Would that work?

Yessir. It would be good for both of you to do a job like that.

 

[BarnyardChaos]

Question, again: Would it be possible to suspend the front edge of the shelf from lag screw eye bolts into separate ceiling joists and steel cable or chain? We used a porch swing for years suspended from a single ceiling joist and two lag screw eye bolts.
Like these:

lag screw eye bolts for the upper attachment, wall or ceiling

eye BOLTS for the shelf

But instead of going into the ceiling joist horizontally (as pictured), can I screw it vertically into the joists from below? My joists run perpendicular to the shelf, so they'd be in separate joists.

OR, would it be possible to attach the lag screw eye bolts into the header at the top of the wall behind the shelf (avoiding joists altogether), angling across to the front of the shelf? Shelf is 30" deep and 16" down from the ceiling surface to top edge of the 2x4 horizontal front support. Too low of an angle?

I'm really reaching to find a way to attach it without crawling into the attic space. You see, the access door to that attic is small. Too small for my son to squeeze through and my grandson is too young yet.

If all other options won't work, I think I will have to (a) cut and enlarge the attic access opening, or (b) cut holes in the ceiling drywall. I'm sorry to keep picking at this, but I need to have a solid picture of all the options available. Thanks for your time and expertise.

 

[BarnyardChaos]

Fortunately, there are some imperfections in the ceiling that clearly indicate where some of the ceiling joists are located Plus a ceiling fan, where I might locate one or both joists around the junction box. With those and a stud-finder, should be easy-peasy!
Thank you both again. I've cleared the whole plan with my husband (disabled, no physical help but he's supportive), and it's a GO. I will post pics!

 

[perkolator]

All thread is simpler to me with less parts, but the eye-bolts and cable system should work just fine if you won't want to go into the attic space. You could also use hooks and chain, which may be easier and cost less than all the parts for making cable ends without a crimper for ferrules. They can run vertical to the ceiling or angle to the back wall.
For that lightish weight load you can likely get away with using 2x3 lumber instead of 2x4, to gain another inch of storage space, and probably only need 1/2" plywood for the sheeting.
Good luck!