Content of the material
- Do Drywall Anchors Work on Plaster Walls?
- Plastic wall anchors, Molly Bolts or Toggle Bolts?
- Two Methods for Filling a Crack
- The Inverted V Method
- The Bonding Method
- Read more from Old House Journal:
- How do you hang plates on a wall without nails?
- How do you hang curtains on a plaster wall?
- Delamination: Finish Coat Failure
- Rubber Anchor Nut
- How to hang pictures on plaster with a plaster hook
- Best Screws for Plaster Walls: FAQs
- What anchors to use in plaster walls?
- How much weight can a screw-in plaster hold?
- Do toggle bolts work on plaster walls?
- What drill bit should I use for plaster?
- Nylon Toggle Plasterboard Fixing
- Repairing plaster walls
- Repairing plaster separated from lath
- Repairing cracks in plaster walls
- Repairing holes in plaster walls.
- The Easy Way to Hang Curtains on Plaster Walls
- Step 1: Mark the Spot for the Bracket
- Step 2: Drill Top Hole
- Step 3: Add Screw
- Step 3: Insert a Molly Bolt Into the Hole
- Step 3.5: Add Screw
- Step 4: Dry Fit Bracket and Mark Second Hole Hole
- Step 5: Drill Second Hole and Add Screw
- Step 8: Add Curtains and Place Rod on Brackets. Secure.
Do Drywall Anchors Work on Plaster Walls?
Drywall anchors are not designed for use on plaster walls. In many cases, drywall anchors will pull out of plaster. This is because many drywall anchors are made to penetrate drywall that is 5/8-inch thick and spread outward at the tip, forming two “wings” that brace against the drywall from behind. This design won’t work on plaster walls because the plaster is too thick. Most plaster walls are more than 1 inch thick. The anchor can’t pierce through the plaster and spread the way it’s designed to, and thus pulls out easily.
- Avoid drywall anchors for plaster walls. They are designed for thin drywall, not thick plaster and lath.
- Do not use self-tapping anchors on plaster walls. The plaster and lath is too hard for the anchor to penetrate.
Self-tapping anchors designed for drywall are not suitable for plaster walls. You can identify self-tapping anchors by their screw shape and pointed tip. Plaster and wood lath are much harder than drywall, so self-tapping anchors are often defeated by plaster. Not only that, but attempting to drive a self-tapping anchor into plaster without pre-drilling a hole can crack the surface of your plaster wall.
Plastic wall anchors, Molly Bolts or Toggle Bolts?
Plastic wall anchors don’t work with lath and plaster walls. Instead, use plaster anchors made of metal like a molly bolt or a toggle bolt. Be sure to use one that’s long enough to get behind the plaster and lath. When drilling into plaster, you’ll need to use a masonry bit. Molly bolts and toggle bolts are ideal for pictures that weigh between 25 and 50 pounds.
Watch the following video to learn how to hang a heavy mirror on plaster wall.
Two Methods for Filling a Crack
There are two methods for filling in the crack once the wall is anchored. They are:
The Inverted V Method
- Dig out the crack along its length in an inverted V shape and vacuum out any residual debris. This should create a toehold for the patch.
- Provided the crack survives without crumbling into chunks, fill and tape it much the same as though it were a drywall joint.
- First wet the lath and plaster around the cleaned crack to help the patch adhere (the old, dry materials tend to suck the moisture out of the new plaster before it can fully cure).
- Then fill the crack with a coat or two of stiffly mixed joint compound to raise and level out the crack.
- Also, take care that the new plaster attaches firmly to the lath by pressing the material through the openings in the slats. Otherwise, the repair will fail.
- Float the crack out with two thinner coats of joint compound, sanding between finishes.
- Finish with a final layer of joint compound or Easy Sand and touch up sanding.
The Bonding Method
Use a PVA (polyvinyl acetate) plaster bonding agent around the edges of the failed plaster and on any exposed lath before taping the crack. The bonding agent acts as an emulsifier to bond the new plaster to the old without the hit-or-miss method of wetting the old lath and plaster. Then fill in the hole as above. Allow each application of plaster to dry and sand between coats.
Read more from Old House Journal:
- How to Repair Plaster Cracks
- How to Repair Textured Plaster
- Prepping Plaster Walls for Paint & Wallpaper
- How to Patch Plaster Walls
How do you hang plates on a wall without nails?
- Step 1: Arrange your plate layout. Determine how many plates you’d like to hang and how they look best.
- Step 2: Trace the plates onto paper. Use a pencil to trace outlines of each plate on a large piece of kraft paper.
- Step 3: Tape the templates to your wall.
- Step 4: Hang the plates on picture hangers.
How do you hang curtains on a plaster wall?
Use approximately a 1/4″ drill bit to drill into a likely spot on your ceiling. If it hits wood all the way through, you’ve just found a joist. If it goes through the lath and hits a void, get a piece of wire or an old coat hanger. Put two bends in it so it looks like three sides of a rectangle.
Delamination: Finish Coat Failure
Often only the top coat of plaster is failing. This is called delamination. If this is the case, scrape off the loose finish coat with a putty knife and brush away loose material. Leave any sound material intact.
Apply a plaster bonding agent (Plaster-Weld is one brand) over the damaged areas. Follow the bonding agent instructions carefully with regard to wall preparation and curing times. Then apply a new finish coat, using either veneer plaster or multiple coats of plaster compound.
Veneer plaster creates a thicker buildup in a single coat than drywall mud. For best results:
- Mix small batches to the consistency of mashed potatoes.
- Bring the plaster directly to the wall with the trowel and apply it in an arcing motion. (This may take some practice.)
- As the plaster begins to dry, brush a coat of water over it and smooth it out quickly. This will help the plaster cure to a smooth finish.
Rubber Anchor Nut
There is one hammer in fixing which we use a lot. Its very easy to use, simply hammer in and it will take a fair bit of weight.
How to hang pictures on plaster with a plaster hook
Plaster hooks (or hanging picture hooks) are a common solution for hanging pictures on plaster wall. They can generally support pictures of up to 20 pounds.
As mentioned earlier, avoid using nails on plaster wall because they will likely cause the drywall to crack. Instead, use a screw, because they won’t break the plaster wall. Screws will also hold a lot better because they will fasten into the lath behind the drywall.
Best Screws for Plaster Walls: FAQs
What anchors to use in plaster walls?
Molly bolt and zinc plated anchor screws are the best anchor for plaster walls. However, in the field of choosing a screw, you must keep in mind whether the screw is long enough for your walls.
How much weight can a screw-in plaster hold?
Metal screws usually support plaster and drywall to carry heavy loads of 25 to 50 pounds or more. On the other hand, the plastic version screw can hold up to 10 to 25 pounds.
Do toggle bolts work on plaster walls?
Metal toggle bolts are perfect for taking heavy loads on plaster walls. However, if you are looking to hang medium and lightweight items, it is best not to use toggle bolts. Its installation process is a bit tricky for beginners.
What drill bit should I use for plaster?
In drilling with a regular drill bit, there is a chance of breaking masonry walls behind the plaster walls. So carbide drill is perfect for plaster.
Nylon Toggle Plasterboard Fixing
The second fixing we use is called a plastic or Nylon toggle.
This is inserted (8mm hole for a medium toggle but always read the hole size on the packet first.) through a pre-drilled hole after squashing it flat.
When a screw is inserted it goes through the hole in the back of the fixing and as you screw it, it pulls the back up to squeeze the fitting against the back of the plasterboard. Once again anything can be screwed to the wall now.
This fitting is also very strong but, if used on their own, heavy items can tend to "tilt" the actual fixing in its hole and while they will not fall off, can become a little loose after a while.
Ideal for shelf brackets which create a pulling force from the wall as well as a weight force downwards.
Repairing plaster walls
There are a few types of common repairs; cracks, missing pieces or separated lath and plaster. The repair method will vary depending on what type of plaster you have and how it was originally installed.
Repairing plaster separated from lath
If the plaster has separated from the wood lath, it’s likely because the “keys”, where the plaster connects to the lath, have broken off. You need to re-attach the plaster to the lath. This can be done with drywall screws but a better solution would be to use “plaster washers”. These washers are either metal or plastic. They are about 1 1/2″ wide, a screw is inserted through the washer and driven into the wood lath. The washer pulls the plaster tight against the lath. You will need these washers every foot or so (or every few inches depending on how bad the plaster is detached) to secure the plaster. Once the washers are installed, and the plaster is stabilized, you then skim a coat of new plaster over the washers to hide them.
Repairing cracks in plaster walls
It seems that cracks in plaster are sometimes unavoidable in old homes. These homes will move with the seasons and cracks will re-appear over time. A traditional approach to repairing cracks involves removing any loose plaster and then filling the crack with new plaster, also using some paper or fiberglass joint tape if the crack is large will help. If the house does move a lot then there may be little that can be done to keep the crack from re-occurring.
If the crack is small, Paul suggests just using a flexible, paintable, caulk in the crack. The flexibility of the caulk gives you a better chance that it will stay put and the crack will not re-appear. If that fails then you can try the more traditional method down the road.
Repairing holes in plaster walls
For repairing a hole in a plaster wall Paul recommends “Patching Plaster”. It’s a fast drying plaster than comes in small containers for small repairs. Check it out and follow the directions on the package.
The Easy Way to Hang Curtains on Plaster Walls
Note: I was using these curtain rods that I purchased off Amazon. I had a lot of big windows to cover, so a four pack of 120″ long curtain rods was perfect for me (and the best value I could find!)
They were super sturdy (and yes, I dropped them multiple times), and only required three brackets (not four,) which I think makes it easier to move the curtains. If you have a bunch of windows to cover, I’d at least take a look at them!
Step 1: Mark the Spot for the Bracket
I was hanging my curtains 100 inches above the ground. I marked where that was, then put my bracket up and marked where the holes should go.
If you’re hanging your curtains high and wide like everyone says to do, make sure there is enough space for the finial (ball thing at end). Mine was dangerously close to hitting the wall.
Step 2: Drill Top Hole
I drilled the top hole first (check your instructions for the drill bit size, mine was 3/16”,) noting if I hit lath or not. I’ve found that plaster really dulls my drill bits, to the point where they struggle to go through wood after being used on plaster. As a result, it’s super obvious when I hit lath, because my drill bit resists moving further. If there’s not lath, my drill bit suddenly lurches into the wall when I finish drilling through the plaster.
Of the 18 holes I drilled to install my three curtain rods, I hit lath fifteen times, and was required to use a molly bolt on the other three holes.
I’ve written two different instructions based on if you encounter lath or not, read what you need!
Step 3: Add Screw
If you hit lath, you can add your screw directly into the wall. I didn’t screw the screw in all the way, so that I could take the hanger on and off to drill the second hole. Once the lower screw and bracket were in place, I tightened this top screw.
Step 3: Insert a Molly Bolt Into the Hole
Molly bolts are typically provided with the curtain rod. They look like this:
Take one and insert it into the hole you’ve already drilled. You’ll need to gently hammer it into place.
If, even after hammering, it doesn’t fit (aka, the bolt crushes instead of sliding into the hole) grab a drill bit slightly larger than the one you were using, and enlarge the hole.
Be careful! The hole doesn’t need to be huge, just a little bit larger, so that a molly bolt will fit when you hammer.
Step 3.5: Add Screw
I don’t tighten the screw all the way yet, so that I can still add/remove the bracket to mark and drill the second hole.
Step 4: Dry Fit Bracket and Mark Second Hole Hole
I then placed my bracket on the first screw, and marked where my second hole should go. It typically was a little different from where I first marked in step 1, which was totally okay.
It’s why I always did this step to double check before I drilled the second hole.
I’m about to mark the second hole!
Step 5: Drill Second Hole and Add Screw
See steps 2 and 3 based on if you hit lath or plaster. Note that when you add the screw this time, you should be holding the bracket in place.
The plaster cracked a bit when I was drilling the second hole. Not a big deal- the hanger will cover this up.
Step 8: Add Curtains and Place Rod on Brackets. Secure
Tighten the screws on the brackets to secure the rod in place!
I’d been dreading hanging up these curtain rods for weeks, but it was done in less than two hours!
Hanging (light) things on plaster walls is not nearly as difficult as I was imagining; the lath makes things so much easier! I’m almost looking forward to hanging the curtains the curtains in the living room (well, not dreading, at least.)
If you haven’t already, check out my super cute curtain tiebacks! The hearts make them perfect for Valentine’s Day, but if you have a a pink room like I do, they’re great year round.