TV Mounting and Heavy Art on Plaster-and-Lath Walls in Older LA Homes

A TV bracket ships with the same bag of lag screws whether your wall is 1928 plaster or 1972 drywall. The wall is what decides how the job goes. In older Los Angeles houses the plaster is thick, brittle and full of lath nails that fool stud finders, and the wiring behind it can be older than the owner. This is what we look at before we drill, and how we decide between toggles, lags into studs and a French cleat.

Plaster-and-lath vs. drywall: how to tell what you have

Houses built before about 1950 were usually finished with wet plaster over lath: thin wood strips nailed across the studs with small gaps, then two or three coats of plaster pushed into the gaps and troweled smooth. The finished wall is roughly three-quarters of an inch to an inch thick, harder than drywall, and it cracks instead of denting. From the late 1940s some builders switched to gypsum board lath with a plaster skim; by the 1960s and 70s tract houses and apartment buildings across the Valley and the Westside were drywall, a half-inch gypsum panel nailed or screwed straight to the studs.

Quick tests: push a thumbtack into an inconspicuous spot. It sinks into drywall and bounces off plaster. Knock: drywall sounds hollow between studs; plaster sounds dense everywhere. Pull a switch plate and look at the edge of the cutout: layered gray-and-white plaster with wood or gypsum lath behind it is plaster; a single paper-faced panel is drywall.

The age of the neighborhood is a strong hint. In ZIP 90068 in the Hollywood Hills, 30.1% of housing units were built in 1939 or earlier, and in Pasadena the figure is 28.6%. Citywide, 19.1% of Los Angeles housing units date from before 1940 and 26.1% were built in the 1960s and 70s. In Encino's 91316, 43.2% of units are from those two decades, which almost always means drywall. (U.S. Census Bureau, American Community Survey 2024 5-year estimates, table B25034, via Census Reporter.)

Finding studs behind plaster

Electronic stud finders read a change in density through a wall of consistent thickness. Plaster is not consistent: it is thicker where it bulges into the lath gaps, and the hundreds of lath nails give a magnet finder a false hit every few inches. So on a plaster wall we do it the slow way:

• Switch the finder to deep-scan mode and take several passes at the exact height of the bracket, marking every reading.
• Confirm with a 1/8-inch test hole where the bracket will cover it. Solid wood past the plaster means a stud; a hole that breaks through into air means a bay.
• Measure 16 inches from the confirmed stud and test again. Many pre-war houses were framed at 16 inches on center, but not all, and studs shift around windows, doors and old wall heaters.
• Use outlets and switches as references: their boxes are nailed to one side of a stud.

A mount that misses a stud by half an inch and bites only lath will hold for a month, then pull out with a chunk of plaster. Confirming studs takes ten minutes and saves a drywall or plaster repair.

Toggles, lags into studs or a cleat: by weight

We sort wall-hung items into three classes.

• Light, under about 15 pounds: framed prints, small shelves, mirrors up to bathroom size. A plaster-rated picture hook or a screw into a stud. We pre-drill the plaster with a carbide bit so the fastener does not crack it.
• Medium, roughly 15 to 50 pounds: large framed art, a heavy mirror, a fixed TV bracket for a smaller set. Snap toggles through plaster and lath hold well because the wall itself is thick and stiff; we still go into a stud whenever the bracket's hole pattern lets us.
• Heavy, 50 pounds and up, or anything on an arm: a 65-inch or larger TV on a full-motion mount, a headboard, a wide floating shelf, a tall mirror. Lag screws into at least two studs, pre-drilled and seated to the depth the mount maker specifies. Toggles are not used for this class. On a full-motion arm the TV sits a foot or more off the wall, and that lever multiplies the pull on the top screws every time someone swings it.

In plaster we drill the pilot hole in two steps: a carbide bit through the plaster with the hammer function off, then a wood bit into the stud. Painter's tape over the spot keeps the surface from chipping. If a stud is not where the bracket needs it, we add a backer: a length of plywood or a painted board lagged into two or three studs, with the bracket screwed to the backer.

What we check before we drill

Older walls hide more than studs. Before the first hole we look for:

• Wiring. Cables normally run vertically from an outlet or switch toward the ceiling or floor, so we do not drill directly above or below a device. Homes from before about 1950 may still have knob-and-tube or cloth-covered wiring, which does not sit in neat runs. We scan with the finder's AC-detection mode and probe the test hole with a plastic rod, not a screw.
• Plumbing. A wall that backs onto a kitchen, bathroom or laundry is a wet wall. Supply lines and vent stacks run through it, so we keep mounts away from the fixture side or confirm the stud bay is empty.
• Wall heaters and flues. Older houses often had a gas wall heater; the flue pipe may still be inside the wall above it.
• Plaster condition. If the plaster has separated from the lath (it moves when pressed, or sounds like a drum), fasteners will crush it. We repair or re-key that section first.

If we open a wall and find a damaged or overloaded circuit, we tell you before going further. Adding an outlet behind the TV or replacing a scorched receptacle is an electrical repair, from $185, quoted as its own line.

Hiding cables where the wall allows

In a drywall wall we can usually fish HDMI and speaker cable from behind the TV down to the equipment and install a recessed in-wall power kit, so nothing shows. The kit has a listed outlet behind the TV and an inlet near the floor; a standard appliance cord is never run inside a wall. Plaster changes the picture: the lath gaps snag the fish tape, older framing may have fire blocking halfway up the stud bay, and every extra opening is a plaster patch. On plaster we typically run cables in a slim paintable surface raceway down to a nearby outlet, or route them behind a console. Where you do want an outlet added behind a TV on plaster, we cut one clean opening, pull the circuit from an existing box, and finish the plaster around the new box.

When a French cleat beats a bracket

A French cleat is a pair of boards with mating 45-degree bevels: one lagged to the wall across two or three studs, the other screwed to the back of the object. The object hangs on the wedge. We use it for large canvases, oversize mirrors, headboards and long floating shelves because the cleat spreads the load across the studs instead of concentrating it on two toggles, it levels itself, and the piece lifts off for painting or moving without new holes. For a landlord furnishing a rental, a cleat also means the next tenant's heavy piece goes up on the same hardware.

What it costs and how to book

TV mounting and heavy-item hanging through our mounting service starts from $120. If the plaster needs patching from an old mount or a failed toggle, drywall and plaster repair starts from $285; an outlet behind the TV is an electrical repair from $185. You get one fixed price for the job before work starts. If you prefer hourly, the rate is $160 for the first 2 hours, then $80-120 per hour depending on the work, and any materials are billed at cost with the store receipt attached. Full details are on our pricing page.

Book a 2-hour arrival window at /request-a-quote; the office usually calls back within about 15 minutes. We are open seven days a week, 8am to 8pm, at (323) 593-3663. Fix Brothers is a family-run company that has worked across Los Angeles since 2015, with a 4.9 rating on Yelp (about 170 reviews) and 4.9 on Google (66 reviews). Our technicians live across the city, so most jobs are within a 30-40 minute drive of one of them, whether you are in the Hollywood Hills, Pasadena, Encino or anywhere else in Los Angeles. Send a photo of the wall and the TV or artwork with your request and we can often quote from it. For anything beyond mounting, see our handyman service.