Hang anything heavy on a plaster wall from the studs, not the plaster. Find the framing behind the lath, tape and pilot-drill the plaster slowly, and drive lag screws into the studs for a TV or loaded shelf. Toggle bolts suit lighter loads between studs, and brick chimneys take masonry anchors set in sound brick.
Plaster or drywall: how to tell
Many older homes in Duluth's established neighborhoods and Superior's older blocks have plaster walls, and plaster changes how you hang things. Three quick tests settle it. Press a pushpin into the wall: drywall takes it easily, while plaster resists and may chip. Knock between spots: plaster sounds dense and solid almost everywhere, while drywall sounds hollow between studs. Then turn off the power, remove an outlet or switch cover and look at the cut edge beside the box. Drywall shows a single layer of gypsum with paper on the face. Plaster shows a hard, often layered edge, and behind it you may see wood lath strips, metal mesh, or gypsum panels.
That backing matters. Wood lath is the most common in older houses. Metal lath shows up in some rooms and repairs, and gypsum lath panels appear under the plaster in some mid-century homes. Plaster is also thicker and harder than half-inch drywall, which is why ordinary drywall anchors often won't fit or grip.
Finding studs behind plaster and lath
Electronic stud finders struggle here. SANUS, the TV-mount maker, notes in its stud-finding guide that lath and plaster walls can obscure studs and confuse the tool, and it lists fallback methods: electrical boxes are attached to a stud, studs usually sit on 16-inch centers but can be as far as 24 inches apart, and tiny test holes in a row will find one as a last resort.
A strong magnet is the best trick on wood lath. The lath strips run across the wall and are nailed at every stud, so slide a rare-earth magnet slowly across at chest height and mark where it grabs. Repeat higher and lower; nail hits stacked in a vertical line mark a stud. In old houses, confirm before you trust any one method, since framing isn't always on even centers, and some old outlet boxes are fastened to the lath rather than a stud. Drill a small test hole where the mount or bracket will hide it. If the bit hits solid wood past the plaster and lath, you've found the stud. On metal lath, magnets stick everywhere, so rely on test holes.
Drilling plaster without cracking the wall
Plaster cracks when a bit grabs, hammers or spins too fast. Put a cross of painter's tape over each hole location to hold the surface together. Start with a small pilot hole using a sharp masonry or carbide-tipped bit, drill in regular rotary mode with the hammer setting off, and use light pressure at moderate speed. Back the bit out often to clear dust. Step up to the final size only after the pilot is through the plaster.
Never drive a screw straight into plaster without a pilot hole, and don't overtighten; a screw cranked hard can pop a patch of plaster off the lath. If an area already sounds loose or hollow, the plaster has lost its grip on the lath, and anything hung there pulls on the weakest part of the wall. Reattach it with plaster washers, or have it repaired, before mounting. We fix loose and cracked plaster as part of drywall and plaster repair.
Anchors versus studs, loads, and brick walls
| Wall type | Fastener | Notes |
|---|---|---|
| Drywall, at a stud | Wood screws or the mount's lag screws into the stud | The standard for TVs and loaded shelves |
| Drywall, between studs | Toggle bolts sized to the load | Light shelves and decor; never a TV arm |
| Plaster on wood lath, at a stud | Lag or structural screws through the plaster into the stud | Pilot-drill the plaster first; best choice for anything heavy |
| Plaster on wood lath, between studs | Toggle bolts through plaster and lath | Pictures, mirrors, light shelves; plastic plugs grip poorly |
| Plaster on metal lath | Toggle bolts, or screws into the studs behind | Magnets won't find studs; drilling is slower |
| Plaster over a brick chimney or wall | Masonry anchors set in the brick behind | Measure the plaster depth so the anchor reaches solid brick |
| Exposed brick or stone | Masonry screws or sleeve anchors, hammer drill | Anchor in sound brick; skip soft or crumbling mortar |
| Concrete block basement wall | Masonry screws or anchors for block | Watch for hollow cores and damp walls |
An anchor's ultimate load is what it held when it failed in testing, not what it should carry every day. DEWALT's toggle bolt technical guide shows the gap: a quarter-inch toggle bolt in half-inch wallboard has an ultimate tension load of 235 pounds but an allowable working load of 60 pounds. The same guide lists plaster as a suitable base material for toggle bolts, but its load tables cover wallboard only, so there's no published plaster figure to lean on; treat plaster between studs as light duty. Plastic expansion plugs tend to crush crumbly plaster instead of gripping it.
For a TV, use the studs every time. A full-motion arm levers the whole weight of the screen away from the wall, so the bracket's lag screws belong in two studs, centered, not at the edge. Shelves work the same way: a deep shelf loaded with books puts far more leverage on its fasteners than a shallow one. For brick chimneys, check that the plaster is sound, drill into solid brick with a hammer drill using the hole size and depth the anchor maker specifies, and keep clear of the flue and any fireplace heat. If you want the TV's power cord hidden in the wall with a new outlet behind the screen, the City of Duluth requires a permit for new outlets, so a licensed electrician installs it under that permit.
Our planning range for TV mounting is $100–$220, and the wall type is one of the things that moves the price. National handyman data puts a shelving job at about $199–$464, according to Thumbtack; that's a U.S. range, not our price, and your flat written quote is the real number.
Can a plaster and lath wall hold a mounted TV?
Yes, when the mount is lagged into the studs behind the plaster. The plaster itself only needs to stay intact around the holes, so it's pilot-drilled first and the bolts, not the plaster, carry the TV. Hanging a TV from anchors in plaster alone isn't worth the risk, especially on a full-motion arm. If no studs line up where you want the screen, a mounting board spanning two studs can fix that.
Why doesn't my stud finder work on plaster walls?
Because plaster is thick and dense, and the wood lath behind it is a nearly continuous layer of wood strips, so the sensor reads wood almost everywhere. Metal lath confuses it further. Use a strong magnet to find the lath nails, which line up vertically at each stud, then confirm with a small test hole that will be hidden behind the bracket or shelf.
What anchors work in plaster walls?
Toggle bolts work best between studs, because their wings spread the load across the back of the plaster and lath. Plastic expansion plugs often spin or crush the plaster. For anything heavy, skip anchors and screw into the studs. Plaster over brick needs masonry anchors long enough to reach solid brick, and a loose or hollow-sounding patch of plaster should be repaired before anything hangs on it.
Have a TV, shelves or a mirror to hang on old plaster? Call or text (715) 919-7956 with the product and a photo of the wall, or send the details. You'll get a flat written quote before work starts, and our on-site service fee is waived when you approve the work.