The Spruce / Adrienne Legault
Lath and plaster walls grace many traditional homes.
They tend only to be repaired, not built from scratch.
Drywall is the wall covering of choice now.
The Spruce / Adrienne Legault
What Is a Lath and Plaster Wall?
The plasterer embeds the lath with three layers of wet plaster.
Plaster and lath wall systems are rarely used except to repair existing walls or refurbish historic buildings.
Drywall Facts
Drywall is produced and cured in the factory.
It arrives on the job site dry, thus the termdrywall.
Unlike lath and plaster, there is no need to wait for it to dry.
Drywall is stiff, lath backing is not necessary.
Drywall can be nailed directly onto the studs.
However, it differs in terms of thickness, soundproofing quality, and insulation.
When lath is figured into the thickness, lath and plaster walls are considered thicker than drywall.
Soundproof drywall, though, rivals lath and plaster walls in terms of soundproofing.
Lath and plaster walls have a slightly better insulating R-value than do drywall wall systems.
Drywall is inexpensive and easy to hang and finish.
Repair
Homeowners canrepair lath and plaster wallsthemselves using drywall materials and tools.
Drywall is easy to repair.
Damaged drywall can be sectioned out and replaced by new pieces of drywall.
Though lath-building can nominally be thought of as carpentry, most plasterers are adept at nailing up lath.
So only one team of workers is needed for the project.
The lath is rough, unfinished wood about 1 inch wide and about 4 feet long or even longer.
Longer lath strips allow the lath to go up faster.
However, since lath is ripped from lower-quality wood, long sections of acceptable wood may not be available.
Sometimes, instead of wooden lath, this base surface is a metal grid.
Apply Plaster to the Lath
A thick layer of wet plaster is hand-troweled onto the lath.
The scratch coat forms the plaster keys (next step) and provides basic coverage.
The brown coat is for further flattening and plumbing (making vertical) the walls.
The white coat provides a smooth surface for painting or wallpapering.
Sometimes, the white coat is textured.
These wet portions cure, forming secure grips for the rest of the plaster.
Prime and Paint the Walls
Plaster is highly porous and must be primed prior to painting.
It is possible to install drywall over lath and plaster.
Drywall is screwed directly into the studs through the lath and plaster.
There are a few provisions, though.
Problems with the lath and plaster will be transferred to the drywall.
So, the lath and plaster does need to be in good condition.
Also, adding another 1/2-inch of drywall extends the wall.
Trim, outlets, light switches, and door casing need to be extended inward accordingly.
Lath and plaster is stronger than drywall.
Lath and plaster has a compressive strength of more than seven times that of drywall.
Lath and plaster is not safe to breathe in.
Inhaling dust from lath and plaster can cause asthma, chronic bronchitis, and emphysema.
Lath and plaster walls cannot hold upa mounted TVif the mount is screwed into the lath.
Lath is weak and splintery, and plaster is brittle and has poor pull strength.
Instead, use a TV stand or screw theTV mountdirectly into the wall studs.
GA2352019 Gypsum Board Typical Mechanical and Physical Properties.
Lathing and Plastering Walls and Ceilings.
U.S. General Services Administration.
Construction Trades | Health Hazards | Plasterer Fact Sheet.
Breathe Freely Australia, The Chartered Society for
Worker Health Protection.
