Historic Preservation - Technical Procedures
- Resecuring Loose Wall Or Ceiling Plaster
- Procedure code:
- Hspg Prepared For Nps - Sero
- Gypsum Plaster
- Last Modified:
- Resecuring Loose Wall Or Ceiling Plaster
- Last Modified:
RESECURING LOOSE WALL OR CEILING PLASTER
A. This procedure includes guidance on resecuring loose
plaster by injecting adhesive behind the loose plaster
and securing it with plaster washers.
B. Plaster is in need of resecuring when sound plaster has
lost its keys and is floating away from the lath or when
the plaster and lath are no longer attached to stud or
C. If wood lath strips are placed too close together, or the
lath is nailed directly over planks, keys do not form
properly and the plaster may eventually sag away from the
lath. Other factors contributing to sagging plaster
include wood shrinkage, weight of plaster or broken
vertical ties (see 09210-06-R).
D. See 01100-07-S for general project guidelines to be
reviewed along with this procedure. These guidelines
cover the following sections:
1. Safety Precautions
2. Historic Structures Precautions
4. Quality Assurance
5. Delivery, Storage and Handling
6. Project/Site Conditions
7. Sequencing and Scheduling
8. General Protection (Surface and Surrounding)
These guidelines should be reviewed prior to performing
this procedure and should be followed, when applicable,
along with recommendations from the Regional Historic
Preservation Officer (RHPO).
A. Charles Street Supply Co.
B. USG Corporation
C. TKO Coatings Company, Inc.
NOTE: When the common name of a chemical is used on the
label, it is usually a sign that the substance is not as pure
as the same chemical sold under its chemical name. However,
the grade of purity of the common-name substance is almost
certain to be adequate for stain removal work, and because it
is likely to be less expensive, the common-name product should
be purchased when available. Common names are indicated by an
A. Denatured Alcohol:
1. Other chemical or common names include Methylated
2. Potential hazards: TOXIC AND FLAMMABLE.
3. Available from hardware store, paint store or
printer's supply distributor.
4. Denatured alcohol should be a satisfactory
substitute for ethyl alcohol for stain removing
B. Plaster Washers suppliers: Charles Street Supply Co., hardware and building supply
firms, internet search, or approve equal.
C. Acrylic, laytex or polymer emulsion adhesive (all water-
based) such as "StrongStik" Construction Adhesive (DAP),
"Liquid Nails", or approved equal.
D. Foam carpet pad
E. Wood shingles
F. Joint compound such as "Durabond Setting-Type Joint Compound"
(USG.com), "Krack-kote" (TKOCoatings.com), or
G. Flat head wood screws or drywall screws and plaster
H. Clean, potable water
A. Electric drill
B. Bent wire tool
E. 1/2 inch plywood
F. 1 x 2 or 2 x 4 wood braces
G. Caulking gun
H. Phillips head screwdriver
A. Determine the extent of the damage and evaluate work
requirements and causes before proceeding.
1. Thumping with a finger makes a solid, snappy sound
on good plaster; it makes a hollow and dull sound
on loose plaster.
2. Gently press the plaster surface with palm of hand
or with a T-brace made from 2x4s; If plaster moves
in relation to the studs and lath, then the keys
are broken; With more pressure, a similar movement
indicates that the plaster is well keyed to the
lath, but the lath is loose from the studs.
3.02 ERECTION, INSTALLATION, APPLICATION
A. Resecuring Plaster by Injected Adhesive Bonding:
1. Determine the areas of loose plaster and mark them
out with chalk (see section 3.01 EXAMINATION).
2. Ceilings (accessible backside):
a. From the backside of the surface to be
repaired, drill 1/4 inch injection holes
through the lath 3-6 inches apart and at the
center of the lath (use a drill stop on the
bit to keep from drilling into the plaster).
b. Using a bent wire tool and a vacuum, loosen
and suck dust out through the injection holes.
3. Ceilings (inaccessible backside) and Walls:
a. Drill through plaster and lath with holes 3-6
inches apart, and if possible, through the
center of the lath.
b. In walls, break-the plaster open at the bottom
of loose areas and vacuum up debris left by
4. Have 1/2 inch plywood as big as the patch area and
enough 1x2 wood braces on hand.
5. Trim the tip of the caulking-gun cartridge so that
it fits in the wood-lath holes.
6. If selected adhesive has an adhesive primer, squirt
into pre-drilled holes according to manufacturer's
7. If adhesive has no primer, mix 4 parts water, 2
parts denatured alcohol and 1 part adhesive (water-
8. Pre-wet both the plaster and lath.
9. Inject adhesive into the pre-drilled holes, giving
the adhesive enough time to flow into the space
between the plaster and the lath.
10. T-brace a 1/2 inch layer of foam carpet padding between the
plywood and the plaster; Add additional braces as
necessary or drive screws through washers and wood
shingles to draw the plaster up against the lath.
11. When the adhesive has set, carefully remove the
plywood (it may need to be twisted gently to break
12. Fill holes and/or tape and mud cracks and finish as
B. Resecuring Loose Plaster with Plaster Washers: Use
plaster washers (also called repair discs or ceiling
buttons) to pull sound plaster back up to the lath (when
the keys have broken), or to pull plaster and lath back
to the studs or joists.
1. If the lath was nailed directly to the joists or
rafters, find the joists, then measure and mark
their locations with chalk lines snapped across the
2. From below, drive 1-1/2 to 2 inch gyp-board screws,
fitted with plaster washers, through the plaster
and lath up into the joists. Space every 4 inches
on each joist where sagging is apparent, or as
often as necessary, and 1-1/2 inches from the edge
of the loose section (only screws that hit lath
3. Tighten the screws gradually all along the edge.
4. Patch the holes with spackling or joint compound
and finish with a skim coat of joint (taping)
A. Remove all rubbish and debris caused by plastering work.
B. Clean all affected surfaces of room and furnishings to
their prior condition.
END OF SECTION