1" Aluminum Angle 1/16th thick - How much shelf weight?

[SabeneGeorges]

TL;DR

How much shelf weight will a 1" aluminum angle support?

I am building a plant rack. Because of size restrictions, I must use angle iron and I want to use aluminum angle because of weight. I am looking at aluminum angle (L shaped) for the shelf brackets. The aluminum angle is 1" and 1/16th thickness, 24" long and screwed into wood. Each angle will be supporting a shelf of 1/2 plywood with some lights attached to the bottom. The angles will be on the 24inch sides, and two 4inch pieces on the back of each shelf to provide additional support. I believe the total weight of shelf, lights, and trays of plants would not exceed 30 pounds.

Will 1/16th thick aluminum angle hold that much weight?

Here is a link to the angle I am considering at Home Depot.
https://www.homedepot.com/p/Everbilt-1-in-x-96-in-Aluminum-Angle-with-1-16-in-Thick-800057/204325583#product-overviewThank you. :)

 

[BvU]

Hello @SabeneGeorges , !

A strip of 1/16 " aluminum is easily bent and will easily bend back. I think it will be too flimsy. Unless they are made a lot sturdier like e.g. https://www.amazon.com/dp/B07TGDN5JY/?tag=pfamazon01-20

Also, I don't see the sense of saving a little weight using aluminum instead of iron if the load is 30 pounds.
Not clear to me what dimension is the 24" : the shelf is how wide? how long ?

(1/2 plywood is probably not half a sheet but 1/2" thick ?)

 

[SabeneGeorges]

Hihi BvU! Thank you for the reply and the welcome. :)

I believe that the angle of having the aluminum bent into an L shape gives it more strength from bending. You could well be correct that at 1/16th, even an angle would not be able to hold up to 30 pounds.

Shelf is 48 long by 24 wide. Planning on putting the angle aluminum on the two 24" sides and a couple of small brackets (4" each) on the back side of the shelf. Plywood shelves will be 1/2 inch thickness, 24x48 inches. :)

 

[BvU]

I still have a hard time imagining what you have in mind. A flat strip of aluminum, bent in an L shape ?

Can you post a picture or a drawing ?

2'x 4' is indeed not half a sheet, but it is a quarter sheet, which I estimate weighs up to 14 lbs

(sorry about the conversions, I can't deal with those units from developing countries )

So there isn't much left for the plants.
The width of 24" is considerable, and I would use hefty supports !

 

[SabeneGeorges]

Here is a link to the exact product.

https://www.homedepot.com/p/Everbilt-1-in-x-96-in-Aluminum-Angle-with-1-16-in-Thick-800057/204325583#product-overview

 

[BvU]

It doesn't like me ?

 

[BvU]

Other websites reveal it's an L-shaped profile like

which you cannot bend yourself without it losing its strength.

 

[BvU]

In addition: it will be hard to keep the weight of the plants+pots low enough with so much shelf space !

 

[Baluncore]

@SabeneGeorges
I think you are selecting angle aluminium because it is easy to drill and conceptually seems to fit the angle between the wall and the shelf. But it will be too thin and will not support the shelf without some diagonal bracing. You should consider making a diagonal bracket that will fit below the shelf.
Search 'shelf bracket' to find things like …
https://www.homedepot.com/p/Everbilt-20-in-x-13-in-White-Heavy-Duty-Shelf-Bracket-14825/202895666
An alternative would be to hang the shelves on ropes or wires from a structure above, or with diagonal rods or wires from wall attachments. You could use aluminium angle to tie the shelf to the wall, but it would not carry the weight. What structure is available in, or above the wall.

 

[Tom.G]

Hi Sabene,

If you look at the end of the shelf, are you proposing to attached the angle aluminum angle horizontally along the wall, and then attach the shelf to the other side of the angle?

If that is the case, without further support, the wall will fail, assuming it is a typical plaster wall.

Here is a simple scenario.
Shelf + plants = 44lbs
Shelf depth = 24in. (for calculation purposes, assume the weight is centered 12in. from the wall. Of course half will be closer and half further away, so we can average the distance.)

Attachment to wall is on the centerline of the angle, or 1/4in. from the edge.

With the shelf loaded there will be 1ft x 44lbs, or 44ft-lbs, trying to rotate the angle toward the floor; this is called the 'Torque', or twisting force.

The angle attachment will be pulling on the screws, and pushing the lower edge of the angle into the wall.

Here is what creates the problem, instead of the 1ft distance to the shelf center, there is only 1/4in from the screws to the edge of the angle. That is 1/48 of the 1ft distance.

Since the torque is 44ft-lbs over 1/4in, the force on the wall will be
44 x 48 = 2112lbs trying to push the lower edge of the angle into the wall, and trying to pull the screws out. (That's about 1 ton of force) (By the way, that is the same principle as pulling a nail with a claw hammer or crowbar, the nail close to the pivot point and a long handle to pull on.)

For a 4ft long (48in) shelf that is 528 lbs per foot, or 44lbs per inch trying to push the lower edge of the angle into the wall. If it is on a plaster wall, the plaster will crumble to powder. You might get away with it on a concrete wall if the aluminum angle is strong enough, which I doubt.

Try this search to get some more practical approaches:
https://www.google.com/search?&q=shelf+supports+wood+site:homedepot.com
The general approach is to decrease that factor of 48 by increasing that 1/4in mounting dimension of the aluminum angle.

The other way is to supply support to the shelf. This could be legs to the floor, hanging from ceiling joists, or braces at about a 45° angle to the wall studs either above or below the shelf.

If you put these new supports at 12in from the front and back edges, the shelf will be close to balanced so there will be little torque on the wall mountings. The drawback is the new supports will be supporting the full weight of the shelf.

Whatever approach you take, be sure you are attaching to the wood structure behind that plaster; plaster itself is very weak.

Hope this helps!

Cheers,
Tom

p.s. the forces go up about 35% if you set a gallon of water on the edge of the shelf.

 

[BvU]

Shelf is 48 long by 24 wide. Planning on putting the angle aluminum on the two 24" sides and a couple of small brackets (4" each) on the back side of the shelf. Plywood shelves will be 1/2 inch thickness, 24x48 inches. :)

Hello again,

It took me a good night's sleep to finally grok the setup . Let's check:

You have two sides 4' apart (a door opening, cabinet sides ? or indeed plaster or cardboard wall ?) and in between you want to install a 2' x 4' x 1/2" plywood shelf, supported by two aluminium L profiles. Front view:

??

??
​

( I was so stuck in the wall-mounted idea that I missed your 24" meaning )

15 lbs per 24" profile will probably hold, but personally I would want considerable reserve (testing with a gallon of water requires that for sure).

Two 4" brackets in the back wall at 16" from the sides won't do very much, except prevent the back edge from sagging. Then there still isn't anything that keeps the front edge from sagging, even from the shelf's own weight alone. How about a 1" x 2" pine strip under the front edge to provide some stiffness (and better looks) ? And then perhaps another under the back edge? And 2" x 2" pine strips instead of the aluminum supports ? (If the walls can handle it -- did I ask for the reason you want to save weight ? -- it seems so out of place in the plant context)