built-inshole-repairshelving
I've used Billy book selves from Ikea to create a built-in unit along a wall. I am going to put the shelves up inline, then I need to fill the rest of the holes which are in the sides. After the holes are filled, it will be painted.
What would work better in this case to fill the holes? Painter's caulk or joint compound. I'm heavily leaning towards joint compound because it is sandable. I just want to ensure I'm not doing the wrong thing.
It sounds like you have a floating shelf. Because of the shear forces, these don't hold very much as they just end up pulling away from the wall.
If you want to pile heavy books on it, you are going to need to support it properly. The words "decorative" and "strength" don't usually go well together. I would think you need something solid and not a rope. With rope you have to worry about tensile strength, stretch and how to anchor it (will the anchor now hold the weight?).
The best thing to do is install a bracket below the shelf to support it. How many of these you need will depend on how long your shelf is and what it's made out of. You could always start with two (one on either end), and if the shelf is sagging, install another one in the center. There are "decorative" brackets out there but the basic principal is the same. Make sure you anchor these into a stud and not just the drywall or else you'll end up just pulling the drywall off your wall.
I took a quick look at the assembly instructions. If you wanted the shelves permanently attached the time to do this was while assembling the cabinet. Instead of using the shelf pins you would use wooden dowels as you did with the non-adjustable shelves.
One issue is that the adjustable shelves are going to be slightly shorter than the permanent shelves because they have to leave room to be inserted as well as room to accommodate the thickness of the shelf pins so you'd need to fill in the gap as well.
At this point I think your best bet is to just use the included shelf pins. Particleboard doesn't hold screws well. If you want to immobilize the shelves you can add a couple of pocket screws on either side of the shelf to lock it in place. A Kreg mini pocket hole jig is affordable and easy to use. I've found multiple uses for mine. If you do a lot of DIY projects you might want to look at some of their more versatile projects because pocket screw joinery helps with a lot of things. Check out my post of which Kreg Jig to buy. They also make plugs to fill in the pocket holes that can be sanded and painted.
I wouldn't recommend just using pocket screws because as I said particle board doesn't hold screws well. The shelf pins should give you better support but the screws will prevent someone lifting off the shelf.
Personally though, I would just use the pins and let gravity do it's job keeping the shelves in place. If the weight of items on the shelves causes the particleboard to break or you want to replace them at a later point because the particleboard has started to bow under the weight it's easier if their just on the pins.
Best Answer
Caulk would be my least preferred. (One can't sand it.) Joint compound is probably okay if you're willing to do a few coats (it'll shrink). Best would be bondo -- the car body filler. (Note that you can catch bondo at a point in its curing cycle when it's firm but pliable and easily cut flush with a sharp chisel/blade. Practice makes perfect on that one.) Texture of any filling you use versus the texture of the billy will be an issue, so you might consider rollering paint on to get an orange peel effect. I'm pretty sure Billy shelves are covered in melamine, so would strongly suggest a melamine primer. (It bonds better than normal primer.)