Mounting suggestions for 1/4 inch plywood shelf back

Question

I have a custom shelf that I built to sit on a desk top but now I want to mount it on the wall. The backing is 1/4 inch plywood. The shelf weighs about 17 pounds and will hold anywhere from 10-20 pounds of items at the most.

Is the 1/4 plywood strong enough to hold that weight with 4 proper anchors? It is only nailed to the shelf but I will attach securely, with many screws.

Also, there are well placed wall studs that I could fasten into directly. Would simple screws going through the 1/4 plywood back and into the studs support the approx. 30-35 pounds max weight?

Answer 1

Given that the plywood is adequately attached to the shelves and dividers, I wouldn't hesitate to mount thusly:

• Use cabinet screws, panhead screws or similar to prevent pull-through. The plywood appears to be just 3-ply, and countersinking flathead screws through the face veneer would substantially reduce holding power.
• Use at least three screws per each of two wall studs, spaced widely and located near shelf or upright attachment. Screws located out in the field could cause bowing of the plywood.
• Pre-drill for each screw to the outer diameter of the threads (or the shaft in the case of partial-thread screws). This will prevent gripping of the back panel, and will maximize holding power of the head by reducing tearout.

You'll know right away if this isn't solid. You'll feel flex in the unit before even loading it. If you're not confident in the back attachment, put some additional screws in it before mounting. Carefully countersunk flathead screws would add plenty of hold.