80" Closet Shelf Design

[Tony Arnold2]

I'm putting a shelf in a closet (and closet rod). It's 80" wide. I'm concerned about the shelf sagging. I want it supported at the ends and the rear only. I don't want a mid support.

I was thinking of making the shelf out of solid 1" x 12" pine and supports out of 1" x 5" pine just like in This Old House video (https://youtu.be/wNQJXdqthmo?t=201).

Using the Sagulator shows excessive sag (https://www.woodbin.com/calcs/sagulator/) with these inputs:


Shelf Material: Pine, Eastern white
Shelf attachment: Floating (not attached)
Shelf load: 50 lbs Center Load
Shelf span: 80"
Depth: 12"
Thickness: 1"
Edge Strip: None
Sag: 0.43" total "EXCESSIVE"


But, this doesn't have the rear support like in the video. With the rear support, would 1" x 12" x 80" have "ACCEPTABLE" sag?

Thanks.

[Mark Bolton]

If you really want 80" I would make a torsion box with 1/4" or 3/8" skins and egg crate core of your choice (ply or sawn material is fine). Glued.

[Jamie Buxton]

You can solve the sag problem for the shelf by making it thicker. Try a shelf that's 2.5" thick in your sagulator calculations. If that gives you an answer you like, but you don't like the weight, consider Mark's suggestion of a torsion box.

However, while you can solve the shelf sagging issue, what are you going to do about the closet pole? Are you going to run it from wall to wall -- without middle supports? If it is the usual diameter, and you fill it with clothes, its sag will likely bother you.

[Prashun Patel]

Why no middle support? A bracket doesn’t have to be too large.

[Malcolm McLeod]

...

Shelf load: 50 lbs Center Load

....

I won't presume to tell you what you will (or won't) store in your closet, but I believe your estimate of load is much too low. I would use ~20lbs/ft as a distributed load for the shelf. I'd figure a distributed load of 30-40lbs/ft of closet rod.

DAMHIK....oh never mind, ask. I've moved my wife's closet contents a couple of times.:(


And Welcome!!

[Bill Dufour]

I would build a angle iron into the front. Either paint it and leave it showing or screw a bull nose trim over it to hide it. A small steel cable to the ceiling might look nice and light.
Bil lD

[Tony Arnold2]

I won't presume to tell you what you will (or won't) store in your closet, but I believe your estimate of load is much too low. I would use ~20lbs/ft as a distributed load for the shelf. I'd figure a distributed load of 30-40lbs/ft of closet rod.

Using 50 lbs Center Load, the total sag was: .43".
Keeping everything the same except using 20 lbs/ft Uniform Load, the total sag is: 0.72". I'll use this estimate instead.

Interesting, if I change it to "Fixed (attached to sides)" (keeping it as 20 lbs/ft) then it has ACCEPTABLE total sag of 0.14". I can screw it into the supports.

The thing is, and no one has commented on this yet... I would think the rear support would help a lot. Right? The rear edge cannot sag. Only the front edge can sag. But, I just have no sense for how much it will help. I was hoping folks here could tell me.

With the rear support and screwed into the supports all around the ends and rear, would that be acceptable?

[Bryan Lisowski]

I would do the cleat in the back, but also add a hardwood edge. I would rerun the sag calculation with a hardwood edge and see what you get.

[Eric Schmid]

The rear support will help substantially as will a front edge glued onto the shelf.

I have a closet which I recently reworked; cleat on back wall, cleats on each side, no front edge, 70” span. The shelf is 1x12 Douglas Fir, not fastened to the cleats. The front edge sagged over 1/2” with no load, mostly from 65 or so years of being in this condition. Plenty strong still to hold sweaters, but the sag wasn’t desirable. The 1 3/8” dowel, not so stable with a load of clothes.

The shelf still sits atop the cleats, but now it’s fastened down. The sag was removed with a center support. Absent a center support, I would have put a 2” or wider front edge on.

[Jim Becker]

The rear and side supports indeed will help with this wide shelf, but please don't underestimate just how much force that putting "stuff" on a shelf can create. Even with a reasonably thick (in proportion) torsion box design, I personally would still likely have some kind of center support. You might be able to span it reliably if you embedded steel angle in the front or mid-way back, but that's a lot of effort.

Eric's suggestion of a dropped front on the shelf would potentially allow you to eliminate a center support and that combined with a steel angle would likely be my choice if aesthetics absolutely required no center support.

[Tony Arnold2]

I would build a angle iron into the front. Either paint it and leave it showing or screw a bull nose trim over it to hide it.

As you and Jim Becker suggested, I think that's a good idea. I guess I'll do that.

Would 1"x1"x1/8" angle aluminum be enough?

[Mark Daily]

As you and Jim Becker suggested, I think that's a good idea. I guess I'll do that.

Would 1"x1"x1/8" angle aluminum be enough?

That size aluminum won’t be enough. I think 1” angle iron would be the minimum for that span but you might need to use 1-1/4”.
Forget aluminum for that span.

[Mark Bolton]

There is no need for any angle iron and I'm not defending the torsion box. A 1 1/2" torsion box will carry the 12" shelf all day long
You just have to decide if you want the work.

The drop leg applied on the front (taller than the shelf) would be far easier but I assumed you'd want the shelf to be a typical shelf.

With the drop leg adding the angle behind would be cheap insurance but unnecessary.

[Jim Dwight]

I agree with Jim Becker. The support at the back will prevent much sag as long and it is fastened solidly into studs. You ought to have several over that span but you need to be sure to screw firmly into them or at least use a decent sized (15 gauge?) nail. But the support at the back will not prevent deflection at the front. Screwing the shelf into the end supports will help the front some but I think a vertical edge is advisable. You can play around some with sagulator on the size. Hardwood will reduce sag more than softwood which is better than plywood. Thicker isn't as important as height but it helps (the deflection equation raises the vertical height to the fourth power).

[Andy D Jones]

Also keep in mind that 1x12 lumber is really 3/4" thick, not 1" as you told sagulator.

I think if you have a closet rod unsupported across that same span, it will also unacceptably sag, so you should probably integrate a center support from the back wall for both rod and shelf, like a heavy duty shelf bracket, and suspend the rod from the shelf at the middle.

Agree with a front hardwood piece on the shelf for additional stiffness. That will likely hide the center shelf support fairly well, especially once clothes are on the rod.

Andy