Q: We would like to hang pictures, some of them rather large, on a plaster wall. Can you tell us the best way to do this? We are afraid of cracking the plaster.
A: With proper technique, hanging pictures on a lath-and-plaster wall isn’t a problem.
If the pictures are small and equipped with a wire on the back, use a small picture hook and nail.
To install small picture hooks, all you need is a hammer. Gently tap the nail provided with the hook diagonally into the wall using the hook itself as a guide. With small hooks there is little danger of cracking the plaster.
Larger hooks may require pre-drilling a hole. A cordless drill equipped with a drill bit slightly smaller than the nail is the tool for the job. Drilling a pilot hole removes some of the plaster and greatly reduces the possibility of cracking the plaster.
Make sure to drill the hole on an angle that approximates the angle of the path of the nail.
For small- and medium-sized pictures you don’t have to be concerned about hitting a stud. The plaster has enough structural integrity to hold their weight.
Be cautious about trying to drive a nail into a piece of wood lath. If a nail strikes a piece of lath under the plaster there is a good chance it will vibrate, break the plaster keys and loosen the plaster from the lath. A “key” is the term used to describe wet plaster that oozed between the lath when applied and dried partially encasing the lath. These “keys” form a bond between the dried plaster wall and the lath.
You’ll be able to tell if the nail strikes a piece of lath — it will bounce back when you tap it with your hammer. If that happens, drill a pilot hole no matter which size nail you use.
For hanging large, heavy pictures we recommend using a wood screw as hanger if the screw can be installed in a stud or a wall anchor if it does not hit a stud.
Wall anchors come in a variety of sizes. They are a two-part fastener, a machine bolt that fits into a collapsible cylinder. Whether installing a wood screw or wall anchor, pre-drill a hole in the wall to inhibit cracking.
For a wall anchor insert the cylinder into the pre-drilled hole, tighten the bolt so that the cylinder compresses and back the bolt part way out of the cylinder and hang the picture. Use two fasteners for very large or heave pictures.
The bottom line is if you have any doubt, pre-drill the holes to avoid cracked plaster.
A month ago we wrote about using plaster of Paris when installing a commode. Apparently our answer created a little confusion with at least one of our readers. She writes:
“I just read your column about using plaster of Paris to mount the toilet. I assume that the plaster of Paris is in place of the wax collar.
“Also, you said not to caulk behind the toilet — leave a 4-inch gap. Is that for condensation to have a way to dry? Wanting it to be very neat, I caulked all around. What bad will happen?”
Neatness is generally good, but you can have too much of a good thing.
Plaster of Paris is not used in place of the wax ring. Rather it is an alternative to caulking under the perimeter of the toilet. Plaster and, to some degree, caulk, are used to stabilize the toilet and prevent it from moving when somebody sits on it.
The wax ring seals the connection between the toilet and the closet bend when the toilet is bolted to the closet flange. Plaster of Paris is particularly helpful on old installations with uneven floors because it is not flexible.
Nothing bad will necessarily happen if you caulk completely around the perimeter of the toilet. However, if the seal between the wax ring and closet flange should fail, the gap at the rear of the toilet allows for water to escape so you can discover the leak. No leak, no problem. But if the perimeter is sealed by caulk, the water has no place to go and could prevent you from seeing water that might cause significant damage.