12TH EDITION 09 23 00/NGC
09 23 00
Kal-Kore BRAND Plaster Base Conventional Plaster Accessories*
DESCRIPTION NO. 15 DOUBLE V
Kal-Kore BRAND Plaster Base panels consist of a fire resistive Minimizes cracking in large
gypsum core encased in blue absorptive face paper and liner plaster areas. Also provides
paper on the back side. Although specifically designed as a ground to ensure proper
base for veneer plaster, it also provides an excellent base for plaster thickness.
conventional basecoat plasters such as Gypsolite or Two-Way
KAL-KORE PLASTER BASE NO. 66 EXPANDED FLANGE
Kal-Kore is available in two
basic types: Regular and Has short, 90 degree return at
Fire-Shield type X. Kal-Kore plaster surface, serving as a
is 4' wide and is supplied plastering stop.
in 8' through 16' lengths.
Thicknesses are as follows:
Regular – 3/8" and 1/2".
Fire-Shield – 1/2" Fire-Shield C,
5/8" Fire-Shield, 5/8" Fire-
Shield C, produced to
meet ASTM C 1396. NO. 1 EXPANDED
Note: Installation of gypsum lath and metal lath shall be in The 2 1/2" expanded flange
accordance with ASTM C 841. Do not use 3/8" Kal-Kore ends 1/4" from the nose
plaster base with conventional basecoat plasters. of the bead providing
DIAMOND MESH LATH
COLD ROLLED STEEL
Used as a plaster base and CHANNEL
reinforcement on almost all types
of walls and ceilings, over wood Used as studs for attaching
or steel framing, flat or curved metal lath in 2" solid
surfaces. Diamonds are 5/16" wide. partitions. For furring or
runners in suspended
SELF-FURRING DIAMOND MESH LATH
Used extensively in stucco work, as a
plaster reinforcement over interior
masonry walls, and in steel column
fireproofing. The self-furring dimples BEAM FURRING CLIP
hold the metal lath 1/4" away from Used to attach lath to flanges
the surface to be plastered. of steel beams, joists and
columns. Tempered spring
1/8" FLAT RIB LATH
Designed to meet the demand for rigid
expanded metal lath used as a
plaster base in all types of work.
Widely used as reinforcement for
basecoat in ceramic tile work.
Sheets are reversible.
Perforated – Ceiling or floor
3/8" RIB LATH support for 2" solid lath
The 3/8" rib lath is used for ceilings and plaster partition.
under steel joist construction and Plain – Ceiling support for 2"
metal reinforced concrete floors. It is solid board partition using
also recommended for concrete slab 1" shaftliner.
floors over steel joists.
*Metal products are not manufactured by
34 NATIONAL GYPSUM CONVENTIONAL PLASTER SYSTEMS National Gypsum Company.
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GOLD BOND BRAND TWO-WAY HARDWALL GYPSUM PLASTER GOLD BOND BRAND GYPSOLITE PLASTER
Gold Bond BRAND Two-Way Strength Gold Bond BRAND Gypsolite LIMITATIONS
Hardwall Plaster is a Two-Way Hardwall Plaster is a lightweight gypsum When used over metal lath, a
basecoat plaster which properly proportioned with basecoat plaster mixed at sand float finish should be
requires the job site aggregate forms a hard, the mill with correctly sized specified. A smooth-trowel
addition of an aggregate durable base for the finish and proportioned perlite finish is not recommended
and water to provide coat. Its high tensile and aggregate, requiring only since the combination of a
working qualities and is compressive strength results the addition of water on the relatively soft (perlite
designed for interior use in increased resistance to job. It is manufactured to aggregated) basecoat and a
over all accepted plaster minor structural be trowel-applied over hard (smooth-trowel
bases. It may be applied by movements, impacts and gypsum or metal lath. lime/gauging) finish has the
hand or used through abrasions. ADVANTAGES potential for cracking and
09 23 00
Fire Resistance spalling of the finish coat.
machines. Uniform Strength and
Two-Way Hardwall Plaster is Hardness Fire Resistance
ADVANTAGES Gypsolite has excellent fire-
essentially mineral in Uniformity is ensured through
Controlled Uniformity composition and will not exact proportioning and resistive qualities and
Two-Way Hardwall Plaster is support combustion. thorough mixing of graded generally provides fire
set-stabilized and adjusted Specification Reference perlite and gypsum plaster ratings higher than sanded
for market requirements at the mill. Gypsolite plaster.
and seasonal changes. ASTM Designation C 28,
“Gypsum Plasters”. provides a uniform base for Specification Reference
When mixed with sand or the finish coat.
other aggregate it has Bag Weight ASTM Designation C 28 for
uniform working qualities Lightweight “Gypsum Plasters”.
100 lbs. (45.4 kg)
and excellent spread. Gypsolite weighs less than Bag Weight
half as much as sanded 80 lbs. (36.3 kg)
gypsum plaster, thus
reducing the dead-load on 25 lbs. (11 kg)
TECHNICAL DATA framing. Water Ratio
High Insulating Value 1.2 gallons of water per 25
AGGREGATE PROPORTION AND ESTIMATED COVERAGE Gypsolite has a “k” factor of lbs. of plaster.
1.5 which provides about
Coverage, Thick- 3 1/2 times the insulating
Aggregate Sq. Yds. Sq. Ft. ness value of sanded plaster.
Pro- per Ton (Sq. M.) In.
portions Plaster Base (Sq. M./Metric Ton) per Bag (mm)
Sanded Gypsum Lath 175-220 80-100 7/16"
1:2-1/2 (161-203) (7-9) (11.1)
Sanded Metal Lath 90-125 40-55 9/16"* GYPSOLITE ESTIMATED COVERAGE
1:2-1/2 (83-115) (4-5) (14.3)* Coverage,
Sanded Brick & Clay Tile 175-220 80-100 9/16" Sq. Yds. Sq. Ft. Thickness
1:3 Concrete Block (161-203) (7-9) (14.3) per Ton (Sq. M.) In.
Plaster Base (Sq. M/Metric Ton) per Bag (mm)
*Measured from face of lath.
NOTE: Sanded 1:2-1/2 means 1 part plaster to 2-1/2 parts sand by weight. Gypsum Lath 140-155 50-55 7/16"
(129-143) (4-5) (11.1)
Metal Lath 65-80 25-30 9/16"*
(60-74) (2-3) (14.3)*
WEIGHT COMPARISON OF BASECOAT PLASTERS
Sanded Gypsolite *Measured from face of lath.
Dry Set Mortar Weight 1.3 Regular
Weight lbs. per cu. ft.(kg/m3) 120 (1922) 50 (801)
Lbs./yd. (kg/m ) 3/8"(9.5 mm) thick
34 (18) 14 (8)
Lbs./yd.2(kg/m2) 1/2"(12.7 mm) thick 45 (24) 19 (10)
Lbs./yd.2(kg/m2) 5/8"(15.9 mm) thick 56 (30) 24 (13)
Lbs./yd.2(kg/m2) 3/4"(19.0 mm) thick 67 (36) 29 (16)
Wet Mortar Weight
Weight lbs. per cu. ft. (kg/m3) 140 (2243) 69 (1105)
NATIONAL GYPSUM CONVENTIONAL PLASTER SYSTEMS 35
PHYSICAL PROPERTIES OF BASECOAT PLASTERS (TYPICAL TEST RESULTS PER ASTM C 472)
Plaster Gypsolite Gypsum Plaster to Gypsum Plaster Gypsum Plaster
Properties Regular Sand by Weight and Vermiculite and Perlite
Regular Masonry Regular Masonry
Mix Mill Mix 1:1 1:2 1:3 100 lbs. (45.4 kg) 100 lbs. (45.4 kg) 100 lbs. (45.4 kg) 100 lbs.(45.4 kg)
2 cu. ft. (.06 m )
3 cu. ft. (.08 m )
2 cu. ft. (.06 m ) 3 cu. ft. (.08 m )
Approximate Compressive 900 1600 1150 750 500 300 900 650
Strength lbs. per sq. in. (kPa) (6201) (11024) (7923) (5168) (3445) (2067) (6201) (4479)
Approximate Tensile 160 250 190 120 130 90 160 100
Strength lbs. per sq. in. (kPa) (1102) (1722) (1309) (827) (896) (620) (1102) (689)
GOLD BOND BRAND GOLD BOND BRAND
GYPSUM GAUGING PLASTER (SUPER-WHITE) GYPSUM MOULDING PLASTER (SUPER-WHITE)
Gold Bond BRAND Gauging Plaster, quick set or slow set type, is Gold Bond BRAND Moulding Plaster is a very white, finely ground
designed for use with finish lime. It is specially ground, gypsum, primarily used for all kinds of ornamental plaster work.
calcined gypsum, which readily mixes with water and lime Because of its low expansion, excellent strength and hardness,
putty. Proper proportioning is essential, since gauging adds it is specially adaptable for casting in rubber, gelatin and other
strength and hardness to the finish surface by reinforcing the types of moulds. For casting purposes, only water is added. For
plastic non-setting lime against shrinkage and cracking. A run-in-place ornamental work, such as cornices, the moulding
finish coat of gypsum gauging plaster and finish lime, job plaster is used with lime putty, mixed 2 parts lime to 1 part
mixed 2 parts hydrated lime to 1 part plaster by weight, is moulding plaster by weight.
designed primarily for interior smooth trowel application over Complies with ASTM Designation C 59.
a gypsum plaster basecoat. Smooth finish plasters should be
applied at a thickness of not more than 1/16". Texture finishes Bag Weight
should be applied at a thickness of not more than 1/8". 100 lbs. (45.4 kg) (50 lbs. (22.7 kg) available in limited areas)
Complies with ASTM Designation C 28. Note: Application of plaster shall be in accordance with ASTM C 842.
Bag Weight Water Ratio
Quick Set – 100 lbs. (45.4 kg) (50 lb. (22.7 kg) bags available in 6.5 gallons of water per 100 lb. bag.
Slow Set – 100 lbs. (45.4 kg) (50 lb. (22.7 kg) bags available in MILL-MIXED FINISH PLASTERS
For a mill-mixed finish plaster, use Kal-Kote Smooth Finish,
Kal-Kote Texture Finish Plaster, Uni-Kal or X-KALibur
TECHNICAL DATA Extended Set Veneer Plaster. Requires the addition of water
only. See page 46.
GYPSUM GAUGING PLASTER
GYPSUM MOULDING PLASTER
Method of Application Coverage*
Trowel Finish 1000-1400 sq. yds./Ton (921-1290 m2/Metric Ton) Method of Application Coverage*
225-315 sq. ft./bag (21-29 m2/Bag) Trowel Finish 1000-1400 sq. yds./Ton (921-1290 m2/Metric Ton)
*With the addition of two tons of hydrated lime. 225-315 sq. ft./bag. (21-29 m2/Bag)
*With the addition of two tons of hydrated lime.
MILL-MIXED FINISH PLASTERS*
Method of Various job conditions such as suction differences, wet or only
Product Application Coverage* partially dry walls, and reactions between paint and lime have
Kal-Kote Smooth Finish Trowel 650-750 sq. yds./Ton caused unsatisfactory paint finishes, particularly on new
(598-645 m2/Metric Ton) construction.
Kal-Kote Texture Finish Trowel 650-750 sq. yds./Ton Alkali-resistant primers specifically formulated for use over new
(598-645 m2/Metric Ton) plaster will permit decorating with oil or latex type paints.
Quality paint products should be used and manufacturers’
Uni-Kal recommendations followed. Finished plaster should be
and X-KALibur Trowel 600-665 sq. yds./Ton painted or covered to conceal possible discoloration. The
(553-613 m2/Metric Ton) paint system should be suitable for use over plaster surfaces
*See page 46 for additional information. that contain lime, which has a high pH of 10-13.
It is essential that plaster be sound and completely dry before
painting. Conventional plaster may require 30 to 60 days to
36 NATIONAL GYPSUM CONVENTIONAL PLASTER SYSTEMS
09 23 00/NGC
Gypsum Plaster Base/Wood Framing 2" Solid-Metal Lath
ATTACHMENT OF GYPSUM PLASTER BASE TO HORIZONTAL Strength
AND VERTICAL WOOD SUPPORTS
This partition with C.R. The completed partition is a
Note: Application of Gypsum Gypsum Plaser Base shall be channel as studs gives fire monolithic slab of gypsum
Plaster Base shall be in applied face side out and protection, stability and plaster thoroughly
accordance with ASTM C attached to wood framing sound insulation while reinforced with expanded
841. with nails or staples. occupying a minimum metal lath and securely
Apply all Gypum Plaster Base Control joints should be amount of floor and anchored to floor and
with long dimensions at installed in ceilings without building space. The system ceiling. It is highly resistant
right angles to the wood perimeter relief with a consists of three metal units to tension, impact, shear
studs or supports. End joints maximum distance (channel stud, metal lath, and vibration.
shall occur on different between such joints of 30' L runners) which are used Adaptability
supports in different with a maximum undivided together with Diamond
courses and shall not be area of 900 sq. ft. With Partitions will accommodate
Metal Lath and Gypsum door bucks of various
nearer than one full stud perimeter relief, maximum Plaster. These components
09 23 00
space from edges of distance is 50' with types, casings, switch boxes
form a space-saving, strong, and electrical outlets; also
openings in walls or maximum undivided area non-load-bearing partition
partitions. of 2500 sq. ft. On side walls support lightweight fixtures
for use in interior wall such as kitchen cabinets.
control joints should be construction.
TECHNICAL DATA installed every 30'. LIMITATIONS
Refer to table of Permissible
Space Saving Partition Heights on
MAXIMUM SPACING OF PLASTER BASE
Occupies less than half the page 38.
Thickness Distance Number of Approximate space of conventional
of Plaster Between Attachments Spacing c to c wood-stud or masonry
Base Supports per Bearing of Attachments constructed partitions.
3/8" 16" 4 5" Cost Saving
(9.5 mm) (406 mm) (127 mm) Simple erection cuts labor
1/2" 24" 4 5" costs. One mechanic can
(12.7 mm) (609 mm) (127 mm) quickly erect the channel
studs and tie on Diamond
NAILS AND STAPLES* MINIMUM GAUGE REQUIREMENTS Mesh Metal Lath.
Flat Head or Composed of gypsum plaster
Blued Nails Gauge of and steel, it makes an
Thickness Length Depth of or Crown Shank of excellent fire barrier.
Attach- of Plaster of Support Width of Nails or Official tests give the
partition a one- to two-hour L RUNNER AT CEILING
ments Base Leg Penetration Staples* Staples*
Nails 3/8" 1 1/8" 3/4" 19/64" 13
(9.5 mm) (28.6 mm) (19.0 mm) (7.5 mm) Sound Insulation
Partition is an effective sound
Staples* 1" 5/8" 7/16" 16 barrier and has a Sound
(25.4 mm) (15.9 mm) (11.1 mm) Transmission Class of 37
Nails 1/2" 1 1/4" 3/4" 19/64" 13 for 2" thick with sand, 33
(12.7 mm) (31.8 mm) (19.0 mm) (7.5 mm) for 2 1/2" thick with perlite
Staples* 1 1/8" 5/8" 7/16" 16
(28.6 mm) (15.9 mm) (11.1 mm)
L RUNNER AT FLOOR
2" SOLID-METAL LATH
CHANNEL STUD SYSTEM
Gypsum Finish Plaster
Sanded Gypsum Plaster
66 CASING BEAD
CR Channel Stud
NATIONAL GYPSUM CONVENTIONAL PLASTER SYSTEMS 37
SPACING OF VERTICAL SUPPORTS FOR ATTACHMENT PERMISSIBLE PARTITION HEIGHTS (BASED ON L/240)
Maximum Maximum Face-to-Face Size and Weight
Spacing Weight Lbs. per Unsupported Plaster of Channels
Type of Lath of Supports Sq. Yd. (kg/m2) Height Thickness (per 1000') (305 m)
Diamond 16" (406 mm) 2.5 (0.6 kg) 12' (3658 mm) 2" (51 mm) 3/4" (19.0 mm) 300 lbs. (136 kg)
Mesh Lath 16" (406 mm) 3.4 (1.9 kg) 14' (4267 mm) 2 1/4" (57.2 mm) 3/4" (19.0 mm) 300 lbs. (136 kg)
16' (4877 mm) 2 1/2" (63.5 mm) 3/4" (19.0 mm) 300 lbs. (136 kg)
Flat Rib Lath 16" (406 mm) 2.75 (1.5 kg) 18' (5486 mm) 2 3/4" (69.9 mm) 1 1/2" (38.1 mm) 475 lbs. (215 kg)
24"* (610 mm) 3.4 (1.9 kg)
3/8" (9.5 mm) 24"* (610 mm) 3.4 (1.9 kg)
*This spacing permissible for solid partitions not exceeding 16' (4877 mm)
3/4" C.R. CHANNEL STUD PLASTER CEILING L RUNNER
3/4" C.R. CHANNEL STUD CORNERBEAD LINE
5/8" 66 1/2" 66
TIE WIRE CASING BEAD CASING
METAL LATH L RUNNER
METAL LATH TAPE
L RUNNER GYPSUM PLASTER
2" 3/4" C.R. CHANNEL STUD GYPSUM
Scale: 3" = 1'-0" 2"
INTERSECTING PARTITION CEILING DETAIL
Scale: 3" = 1'-0" Scale: 3" = 1'-0"
3/4" C.R. CHANNEL STUD
STRAP ANCHOR CEILING
L RUNNER DOOR PLASTER
GYPSUM METAL LATH
METAL LATH BACK-TO-BACK
3/4" C.R. CHANNEL STUDS
METAL DOOR FRAME BASE DETAIL
Scale: 3" = 1'-0" Scale: 3" = 1'-0"
38 NATIONAL GYPSUM CONVENTIONAL PLASTER SYSTEMS
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Fireproofing Columns and Beams
with Metal Lath
Gypsum plaster, mixed with sand or lightweight aggregate, is CONCRETE
CELLULAR STEEL FLOOR
applied over a metal lath base providing an economical fire
protective covering for structural steel columns.
This system of fireproofing weighs only half as much as tile and
one quarter as much as standard concrete for equivalent fire 3 1/8"
resistive ratings. This means a reduction of up to 1/3 in dead-
load weight, reducing the size and cost of footings,
foundations and structural framing.
BEAM FURRING CLIPS
Fire Resistance PLASTER
09 23 00
Fire resistance ratings up to four hours can be obtained.
Economy 3.4 LB. DIAMOND MESH
Lath is low in cost, quick and easy to apply, thereby effecting
savings in material and labor costs.
METAL LATH BEAM
LIMITATIONS 1 1/2"
In warehouses or other occupancies where columns might be
damaged, angle iron guards are recommended to protect GYPSUM PERLITE PLASTER 1 1/2"
column corners to the necessary height.
Scale: 1 1/2" = 1'-0"
2 HOUR - 1"
3 HOUR - 1 3/8"
4 HOUR - 1 3/4"
COLUMN - UL X402
Scale: 1 1/2" = 1'- 0"
NATIONAL GYPSUM CONVENTIONAL PLASTER SYSTEMS 39
Suspended Metal Lath Ceilings
Metal lath suspensions are should be installed around
commonly made below the periphery.
virtually all types of Metal Lath is frequently used
construction for fire-rated for furred as well as
and non fire-rated plaster suspended ceilings.
ceilings. Framing of 1 1/2"
C.R. channels are spaced Metal lath is used for furring
up to 4' o.c. perpendicular from wood, concrete and
to joists and are cross- steel joists.
furred with 3/4" C.R. RECOMMENDATIONS
channels spaced according 1. Control joints should be
to specifications for types installed in ceilings without
and weight of metal lath. perimeter relief with a max-
Lath is then properly imum distance between
lapped at sides and ends such joints of 30' with a
and tied every 6" to the maximum undivided area
3/4" channel. of 900 sq. ft. With perime-
Where it is advisable to install ter relief, maximum dis-
unrestrained ceilings, tance is 50' with maximum
having perimeters undivided area of 2500
separated from adjacent sq.ft.
walls or partitions, 2. Use three-coat plastering on
galvanized casing beads metal lath.
SIZE AND SPACING OF CHANNEL FOR SUSPENDED CEILINGS SIZE AND SPACING OF CHANNEL FOR FURRED
AND SUSPENDED CEILINGS
Center to Main Channel
Center Spacing Size of (weight Maximum 3/4" (19.0 mm) C.R. Channel Maximum
of Hangers Cold Rolled per 1000 ft.) Center to Center Center to Center Cross Furring 300 lbs. Furring
Along Channel Channel (305 M) Spacing of Channel Spacing of Hangers (136 kg)/1000 ft. (305 M) Spacing
up to 3' 1 1/2" 475 lbs. 4' up to 3' (914 mm) 3/8" (9.5 mm) rib lath 24" (610 mm)
(914 mm) (38.1 mm) (216 kg) (1219 mm) up to 3' (914 mm) 3.4 lb. (1.5 kg) flat rib lath 19" (483 mm)
up to 3'6" (1067 mm) 3.4 lb. (1.5 kg) mesh lath 16" (406 mm)
up to 3'6" 1 1/2" 475 lbs. 3'6" up to 4' (1219 mm) 2.5 lb. (1.1 kg) mesh lath 12" (305 mm)
(1067 mm) (38.1 mm) (216 kg) (1067 mm)
up to 4' 1 1/2" 475 lbs. 3'
(1219 mm) (38.1 mm) (216 kg) (914 mm) MAXIMUM SPACING OF SUPPORTS FOR METAL LATH
Support Weight of Lath
Type of Lath Spacing lbs. per sq. yd. (kg/m2)
(flat expanded) 16" (406 mm) 3.4 (1.9)
Flat Rib 16" (406 mm) 2.75 (1.5)
19" (483 mm) 3.4 (1.9)
DETAILS 3/8" (9.5 mm) Rib 24" (610 mm) 3.4 (1.9)
CHANNEL HANGER WIRE
1 1/2" C.R.
1 1/2" C.R. 1 1/2" C.R.
TIE WIRE CHANNEL CHANNEL
66 CASING BEAD PLASTER
FLEXIBLE DUST SEAL
METAL LATH NO. 15
FINISHED WALL LINE 66 CASING BEAD EXPANSION JOINT
SUSPENDED METAL LATH AT WALL (UNRESTRAINED) LIGHTING TROFFER
SUSPENDED METAL LATH CONTROL JOINT
Scale: 3" = 1'-0"
Scale: 1 1/2" = 1'-0" Scale: 3" = 1'-0"
40 NATIONAL GYPSUM CONVENTIONAL PLASTER SYSTEMS
09 23 00/NGC
BAR JOIST HANGER WIRE
1 1/2" C.R.
3/4" C.R. 1 1/2" C.R. 3/4" C.R. CHANNEL
CHANNEL CHANNEL CHANNEL
TIE WIRE GYPSUM
66 CASING BEAD
METAL LATH CAULK
66 CASING BEAD FINISHED WALL LINE
09 23 00
FINISHED WALL LINE CHANNEL PLASTER METAL LATH
SUSPENDED METAL LATH AT WALL (UNRESTRAINED) FURRED METAL LATH CEILING SUSPENDED METAL LATH AT WALL (RESTRAINED)
09210N 09210P 09210L
Scale: 3" = 1'-0" Scale: 1 1/2" = 1'-0" Scale: 3" = 1'-0"
CONCRETE 3/8" RIB
FLOOR METAL LATH BEAM
1 1/2" C.R.
3/4" C.R. CHANNELS
1 1/2" C.R.
CHANNEL BEAM FURRING CLIPS
NO. 11 W AND M GAUGE
NO. 1 EXPANDED
PLASTER 3/4" C.R. METAL LATH CORNERBEAD
CHANNEL GYPSUM PLASTER
SUSPENDED METAL LATH CEILING BEAM PROTECTION
Scale: 1 1/2" = 1'-0" Scale: 3" = 1'-0"
SECTION 09 23 00 4. C 841, Specification for Application of Interior Lathing
GYPSUM PLASTERING and Furring.
THE FOLLOWING PARAGRAPHS ARE FOR INSERTION INTO SECTIONS OF 5. C 842, Specification for Application of Interior Gypsum
GENERIC SPECIFICATIONS OR GENERIC/PROPRIETARY SPECIFICATIONS
COVERING GYPSUM PLASTER PRODUCTS. THE NATIONAL GYPSUM PART 2 PRODUCTS
COMPANY PRODUCT NAME FOLLOWS THE GENERIC DESCRIPTION IN 2.02 MATERIALS
A. Gypsum Plaster Base:
PART 1 GENERAL 1. Regular: A gypsum core lathing board surfaced with
1.02 REFERENCES absorptive paper on front, and long edges and
A. American Society for Testing and Materials (ASTM): complying with ASTM C 1396
1. C 28, Specification for Gypsum Plasters. (Kal-Kore BRAND Plaster Base).
2. C 59, Specification for Gypsum Casting and Molding a. Thickness: 1/2"
Plaster. b. Width: 4'
c. Length: 8' through 16'
3. C 1396, Specification for Gypsum Board (Gypsum Base d. Edges: Tapered
for Veneer Plaster).
NATIONAL GYPSUM CONVENTIONAL PLASTER SYSTEMS 41
2. Fire-Resistant: A gypsum core lathing board with RECOMMENDATIONS
additives to enhance the fire resistance of the core and
surfaced with absorptive paper on front, and long edges
and complying with ASTM C 1396, Type X. BASECOAT PLASTER PROCEDURES
a. Thickness: 1/2" (Kal-Kore BRAND Fire-Shield C Plaster Two-Coat Work
Base) or 5/8" (Kal-Kore BRAND Fire-Shield and Fire- Apply first coat with firm pressure to form good bond on the
Shield C Plaster Base). Gypsum Plaster Base or masonry base; then immediately
b. Width: 4' double back (without cross-raking first coat) using material of
c. Length: 8' through 16' same proportion to build proper basecoat thickness. Straighten
d. Edges: Tapered to a true surface (without applying water) to receive the
3. Regular, Foil-Backed: A gypsum core lathing board second (finish) coat.
surfaced with absorptive paper on front, and long edges; Surface should be left sufficiently rough and porous to provide
backed with aluminum foil; and complying with ASTM suitable bond of the finish coat.
C 1396 (Kal-Kore BRAND Foil-Back Plaster Base). Three-Coat Work
a. Thickness: 1/2" “Scratch” – “brown” – finish is generally used for metal lath or
b. Width: 4' masonry bases, and is performed in discrete steps.
c. Length: 8' through 16'
d. Edges: Tapered • Scratch (first) coat: Should be applied with sufficient
material and pressure to obtain good bond over solid
B. Gypsum Plaster: bases or form full keys through metal lath. Provide
1. Base Plaster: Gypsum neat plaster complying with ASTM suitable material thickness for scratching (raking) to
C 28 (Gold Bond BRAND Two-Way Hardwall Gypsum obtain good mechanical keying of the “brown” coat.
Plaster). • Brown (second) coat: Shall be applied after the scratch
2. Base Plaster: Gypsum plaster with mill-mixed perlite (first) coat has set hard and still damp. Apply to give
aggregate complying with ASTM C 28 (Gold Bond BRAND mass and surface as for double-back in two-coat work.
Finish Coat Plaster Procedures
3. Finish Plaster: Gypsum gauging plaster complying with
ASTM C 28 (Gold Bond BRAND Super-White Gauging General Requirements (Basecoat Condition)
Plaster Quick Set and Gold Bond BRAND Super-White Application over a partially dry basecoat is preferred. If basecoat
Gauging Plaster Slow Set). is thoroughly dry, wet with even application of water to a
4. Finish Plaster: Gypsum moulding plaster complying with semi-dry condition. Avoid excess water. Do not apply finish
ASTM C 59 (Gold Bond BRAND Super-White Moulding to basecoats having free water on the surface.
Plaster). Application – Gauged Lime Putty Trowel Finish
5. Finish Plaster: Gypsum plaster for smooth finish Smooth Finishes
complying with ASTM C 587 (Kal-Kote BRAND Smooth • Scratch in tightly over the basecoat, covering the
Finish Plaster). surface completely, then double back immediately
6. Finish Plaster: Gypsum plaster for textured finish with material from the same gauge, filling out to a true,
complying with ASTM C 587 (Kal-Kote BRAND Texture even surface with total thickness of not more than 1/16".
Finish Plaster). • Allow finish to “draw” (lose moisture to basecoat and
7. Finish Plaster: Gypsum plaster for smooth finish ambient air) and firm up – then trowel it well to
complying with ASTM C 587 (Uni-Kal BRAND Veneer compact and close the surface under the edge of the
Plaster). trowel. Dash water on the surface for lubrication and
8. Finish Plaster: Gypsum plaster for smooth finish development of soft material along trowel’s edge to fill
with extended set time complying with ASTM C 587 surface depressions or other blemishes.
(X-KALibur BRAND Veneer Plaster). • When finish plaster setting action is under way, a
second (final) water troweling can be done with strong
pressure to obtain a polished surface if desired.
PART 3 EXECUTION
• Apply finish as above to a true, even surface with total
A. Metal Lath, Gypsum Plaster Base, and Accessories: In thickness not more than 1/8".
accordance with ASTM C 841.
• Allow finish to “draw” (lose moisture to basecoat and
B. Gypsum Plaster: In accordance with ASTM C 842 and the ambient air). Then begin floating, texturing, or skip
manufacturer’s recommendations, National Gypsum troweling to achieve desired texture. Additions of
Company “Gypsum Construction Guide.” clean graded silica may be required to achieve
C. Tolerances: For flatness of surface, do not exceed 1/4" in desired texture.
8' for bow or warp of surface and for plumb and level. Drying
Conventional plaster systems should be allowed to dry
30 days minimum under ambient conditions prior to
final decoration. Variances in humidity or poor drying
conditions may affect the drying process.
Gypsum plaster must be kept dry before use.
Storage conditions vary with location and
seasonal changes, which may affect storage life.
These conditions may affect product characteristics
such as setting time, working qualities, component
For additional information separation, or lumping, etc. Such aging is normally
a function of exposure to humid air, temperature,
® Phone 1-800-NATIONAL and physical support in warehousing. Adverse storage
(1-800-628-4662) conditions or prolonged storage may affect the working
qualities of the product. Rotate inventory frequently for
42 NATIONAL GYPSUM CONVENTIONAL PLASTER SYSTEMS