What screws should I use for my floating Ikea bookshelf?

Question

I recently purchased a floating bookshelf from Ikea. The following links are to the bookshelf and to the assembly directions of the bookshelf.

https://www.ikea.com/us/en/catalog/products/40103751/

https://www.ikea.com/us/en/assembly_instructions/lack-wall-shelf__AA-10128-11_pub.pdf

I will be placing books on these shelves that weigh about 40-45 pounds.

My walls are 1/2inch Drywall.

Originally I wanted to use toggle bolts but I'd rather use something that's less damaging to the wall.

The shelf takes 16 screws so I decided to go with this threaded anchor.

Do you guys think that if I use 16 of these threaded anchors, in the assigned spots indicated by the manufacturer, then the floating bookshelf will be able to hold up the 45 pounds of books that I'll be placing on it?

Answer 1

I wouldn't use anchors for a shelf holding 45 lbs. unless I had no other choice.

Since the shelf is ~ 6 feet long, see if you can position it horizontally so that at least one of the pairs of holes in the bracket is in front of a stud. Then use appropriate screws (which type will depend on whether you have metal or wood studs) to mount that pair of holes. Then use anchors for the rest. If you can get two pairs to line up with studs that would be even better - and then I wouldn't bother with anchors in the other 6 pairs of holes. But one pair of screws in studs would hold the shelf up and the anchors in the other locations would keep it straight.

EDIT:

Based on one of the comments I took another look at the wordless instructions. It looks like there are 16 holes in the bracket, probably for simple symmetry - mount either way up and it makes no difference. But the instructions indicate only using 8 screws - two above each of the 3 supports and two lower in between. I recommend using either two in one pair (top/bottom) into one stud plus anchors in as many others as you can (but at a minimum matching at least the 8 total in the instructions) OR at least two screws into two separate studs - but once you are doing that you might as well do 4 - top/bottom in each of two separate studs.

If horizontal positioning requirements (e.g., walls, windows, furniture) don't let you get into any studs then you may want to consider drilling two holes through the bracket in order to match it to two studs. That will void your warranty, but it will be a lot more secure than the anchors. I remember ~ 33 years ago at an office where maintenance came in and installed shelves to support PC tape drives (probably 20 - 30 lbs) and the shelves started coming down pretty fast because the supports were not in studs.

Answer 2

Did they have chalk when you went to school? Soak newspaper in diluted Elmers glue, wrap it around a stick of chalk, let it dry, that's pretty much what drywall is. You wouldn't expect that to carry a load, would you?

Your wall probably has wood or metal studs typically 16" on center, sometimes 24", unless it covers concrete or cinder block. Of course the IKEA product is metric, so we can't expect it to line up with 16/24" centers unless they were rather clever.

The UPPER holes nearest the poles do 90% of the weight carrying. Either one will do. The lower holes just keep the unit from flopping upwards. Can't hurt, won't help much.

So find your studs in the walls and figure out how to position the Ikea unit to get the best weight transfer onto the studs. Ideally position it so both outer poles are well supported near studs. Feel free to drill extra holes in the IKEA mounting bracket, again the upper holes are the ones doing all the work. You are drilling into steel, "feeds and speeds" matter, feed is downforce (roughly) and speed is drill speed. When you're in the sweetspot, the drilling is fast and the chips are long.

If you just can't make things line up the way you want, another option is get a piece of hardwood 1" thick (preferably 1.5") and the size of the backing plate. Position it exactly where you want, attach the hardwood to every stud it overlaps, then attach the IKEA mounting bracket to the hardwood as instructions direct but with 1-1/4" screws. The trick to working with hardwood is pre-drill every hole so it doesn't crack the wood, and drill a slight countersink for the screws into the wall so the Ikea backplate doesn't ride up on their heads. Bonus points if you drill extra holes in the Ikea backplate and run them straight into the stud as well.

Never drill more than 1-3/4" below the wall's surface. The standard for construction is that wires and pipes must be at least that far away from the wall surface or be guarded by a metal plate to make them difficult to drill through. If you carelessly use 3" screws and nick a wire, it can break wires or pipes - even electrify the entire shelf!