Tuesday, April 21, 2009

Hanging Things on Drywall and Hollow Doors

Hanging pictures on drywall or installing hooks on a hollow door can be tricky. The surface is thin so nails and screws easily pull out, especially when hanging heavy pictures and mirrors. Hanging hooks is even more problematic because they act like levers pulling the screws out of the wall. Like this:
You can use mollies, which are small plastic wedges which insert into a pre-drilled hole. When you insert a screw into these wedges, they expand outward and create a strong grip on the door or drywall. But when you need a very strong hold, a the best option is to use toggle bolts. These specialized bolts have a butterfly bolt which expands outward with the help of a spring. Slide one of these through the wall or door and the wings will open inside on the other side. Once tightened, they provide a lot of holding force because the pressure is applied across a large area. Think about it this way, a screw or nail holds because of friction between the threads and the wood/drywall. If you're hanging something on a door with a 1/8th of an inch thick wood veneer, that's not a lot of friction. A toggle bolt on the other hand grabs on to an inch or more of material on the inside of the door, providing a very strong hold. The toggle bolt I'm using is one of the smaller sizes which fits in a 3/8ths inch hole. Note that I'm only drilling one hole and only using one toggle bolt. One bolt is more than strong enough for this hook, plus if I drilled three 3/8th inch holes so close together, the remaining swiss cheesed veneer would not be strong enough to hold the toggle bolts.
Because the bolt is longer than the door is thick, I need to trim off some of the end of the bolt. Otherwise when I tighten the bolt, the other end will be pushed out the other side of the door. This problem will not arise with a wall because they are thicker than a door.

This is what the hook will look like with the toggle bolt deployed inside the door. That's a lot more holding force than a tiny little screw.
Even though the other two screws already pulled out of the door once, I'm still going to reinstall them with a little solvent based glue (Gorilla Glue). This won't provide much holding power (which the toggle bolt will more than make up for) but it will prevent the hook from rotating on the one strong anchor.

1 comments:

Darkoshi said...

Good info. I installed a magnetic doorstop on a hollow door today. It has one part on the wall and another on the door. I originally thought I was going to need to use toggle bolts in the door, and I was worried because the 2 holes needed to be very close to each other. After reading your post, I decided to use one toggle bolt and one regular screw. But then I realized that the door is actually nearly solid in the location where I was going to attach the piece (bottom side edge). So I was able to use regular screws after all.

But other times, I've used molly bolts or toggle bolts to install hooks and towel racks on the hollow doors.