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How to install a heavy duty shelf bracket properly

How to install a heavy duty shelf bracket properly

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Old 04-26-17, 08:12 AM
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How to install a heavy duty shelf bracket properly

Hi all,

I'm installing some of these shelf brackets to support a 10 gallon fish tank. The tank itself will weigh 80-100lbs max when full. These brackets say they can support 1000 lbs when "installed properly" :-). I am planning to use two of them, spaced 16" apart installed on studs. The tank is 22 inches wide and will sit on 3/4 plywood between the tank and brackets. I'm using 1 1/2 inch long lag bolts with washers. Finally, I want to install 4 sets of these (4 10 gallon tanks) stacked vertically, each with their own set of brackets and into the same set of studs.

I guess my first question is, how is the weight distributed in this setup? is all of the weight on the lag bolts and 2x4 studs? Should the bolts be longer?



https://www.lowes.com/pd/Style-Selec...racket/3034237
 
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Old 04-26-17, 08:24 AM
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I don't see where they give any info on 'installed properly'
What type of wall covering is over the studs? drywall? Most if not all of the weight gets transferred to the brackets and studs.
 
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Old 04-26-17, 08:42 AM
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right! So I'm installing them directly onto the studs, no wall covering. That's one thing I'm trying to understand. If they say 1000lbs and these are angle brackets (I'm not an engineer) is the weight on the lag screws or or the studs or what? I have this fear the screws wont hold. Maybe I can get access to the back of the studs and use lag bolts?
 
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Old 04-26-17, 08:54 AM
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Assuming the lag bolt is going into the 1.5" side of the stud and not the 3.5" I don't see where a bolt would be necessary. IF I made any changes it might be to add a stud/bracket in the middle .... but that might just be overbuilding it
 
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Old 04-26-17, 09:58 AM
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Here's a better illustration (I hope) of what I'm doing. If I'm unsure this will hold at all (can't risk it breaking) I'll switch the design to using all 2x4 shelving so that a vertical 2x4 compressed is holding the weight.

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Old 04-26-17, 01:09 PM
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Being an Engineer who always over-engineers everything I'd install three brackets over three studs with 3" lag bolts and enjoy the peace of mind knowing it's not coming down!
 
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Old 04-26-17, 01:39 PM
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Ok you think that would do it? Only problem is I only have two studs available behind the wall. The width of the tank is only 22" and the width of my wall is 24".


Could I install a 3rd "floating" stud inbetween the two, tied by a cross piece? Something like this?

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Old 04-26-17, 01:54 PM
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If they say 1000lbs and these are angle brackets (I'm not an engineer) is the weight on the lag screws or or the studs or what?
I believe that would require force vector analysis and it's been far, far too long since I did any of those.

The weight is being applied to the top leg of the brackets, this translates into some force being applied straight down and some out at an angle trying to pull the bolts straight out of the stud. The closer the weight is to the vertical leg, the less force is pulling out. The further away from the vertical leg, less force being transmitted straight down and more trying to pull out. Yours will be pretty equally distributed from back to front, but pull out is the most likely issue. Your weight is all static as well, not a moving load, so that's an advantage.

I'd screw the added 2x4 to the stud just to hold it in place, then lag bolt the bracket to the added 2x4 all the way into the stud using 3" lags.
 
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Old 04-26-17, 02:46 PM
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The brackets exert both shear force and pull out force on the lags; they are very strong in shear. The lags experience pull out force due to weight of the tanks, with the top lag experiencing the most pull out force and the bottom lag very little pull out force.

The pull out force for a 5/16 lag screw into long grain of Spruce is about 200 pounds per inch of full diameter threads. Pine and fir are higher. Based on that figure, your original design is more than strong enough to support the 100 lb tanks with plenty of safety margin assuming your lags penetrate the 2x4 at least 2 inches.


Your drawing states you will fasten the external 2x4 to the stud with 3 inch wood screws. Your drawing shows only one near the top and that would be a weak point. There is a lot of pull out force on that top screw. I would use a couple of lags screws at the top; wood screws would be fine lower down.
 
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Old 04-27-17, 08:04 AM
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awesome! just what I was looking for!. thanks all!!!
 
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