In Canada (BC) studs are usually 16” on center apart. For this illustration we will use this standard.
The stud’s location (16” center) is not always perfect, therefore we need 1” of the bracket to be past each side of each stud for safety.
This is our recommendation, since load capacity calculations were calculated by hitting two (2) studs, using four (4) pan head wood screws 2 ½ inches long (Top and Bottom), and using 3 set screws (#18 - 5/16 – ¾”long) per 24 inch long shelf.
As you can see in the diagram above, the screw head is already (3/8) big and we only have 7/16 to drill into. The screw itself is only 3/16 thick, however, if you drill to the right, you will miss the stud. If you are straight on you are only in the stud by ¼ of an inch. If you drill to the right you are fine, but then the pan head screw does not sit flush on the bracket anymore.
And most important to remember is that NO STUD IS PERFECT. They are often warped, not exactly at 16” center, etc.
Here are some basic guidelines that may help you plan your project:
Bracket Length Studs Shelf Size Max. Shelf Size Min. Comments
18” 2 30” 19” NOT recommended
20 “ 2 36” 21”
24” 2 44” 25”
32” 2 46” 33”
32” 3 - - NOT recommended
35” 3 47” 36” NOT recommended
37” 3 57” 38”
40” 3 60” 41”
46” 3 62” 47”
48” 3 64” 49”
48” 4 - - NOT recommended
50” 4 60” 51” NOT recommended
50” 4 70” 51”
54” 4 72” 55”
60” 4 76” 61”
64” 4 80” 65”
64” 5 - - NOT recommended
67” 5 84” 68” NOT recommended
68” 5 88” 68”
72” 5 90” 73”
76” 5 94” 77”
80” 5 96” 81”
80” 6 - - NOT recommended
82” 6 98” 83” NOT recommended
84” 6 104” 85”
88” 6 106” 89”
94” 6 110” 95”
96” 6 116” 97”
96” 7 - - NOT recommended
Maximum load capacity of 300 lbs is calculated 8 inches off the wall, spread across the length of the shelf