2. WHAT IS GYPSUM ?
Gypsum is a mineral found in sedimentary rock formations in a crystalline form known as calcium sulfate
dihydrate CaSO4•2H2O.
The manufacturer receives quarried gypsum, and crushes the large pieces before any further
processing takes place. Crushed rock is then ground into a fine powder and heated to about 350
degrees F. It is then used as the base for gypsum plaster, gypsum board and other gypsum products.
Synthetic gypsum, commonly known as the FGD (Flue Gas Desulphurization) gypsum or DSG
(desulphurised) gypsum may also be used in the production of gypsum board. This product is primarily
derived from coal-fired electrical utilities which have systems in place to remove sulfur dioxide from flue
gasses. The synthetic gypsum is then transported to the gypsum board manufacturer; the production
process for calcining synthetic gypsum is largely the same as with mined gypsum only no primary
crushing is necessary.
3. WHAT IS GYPSUM BOARD?
Gypsum board is the generic name for a family of panel
products that consist of a noncombustible core, composed
primarily of gypsum, and a paper surfacing on the face, back
and long edges. Gypsum board is one of several building
materials covered by the umbrella term “gypsum panel
products.” All gypsum panel products contain gypsum cores;
however, they can be faced with a variety of different materials,
including paper and fiberglass mats.
Gypsum board is often called drywall, wallboard, or
plasterboard. It differs from other panel-type building products,
such as plywood, hardboard, and fiberboard, because of its
noncombustible core and paper facers. When joints and
fastener heads are covered with a joint compound system,
gypsum wall board creates a continuous surface suitable for
most types of interior decoration.
4. ADVANTAGES OF GYPSUM BOARD CONSTRUCTION
Gypsum board walls and ceilings have a number of outstanding advantages:
Ease of installation
Fire resistance
Sound isolation
Durability
Economy
Versatility
5. ADVANTAGES OF GYPSUM BOARD CONSTRUCTION
1. Ease of installation
Gypsum board building systems are easy to install for several reasons. Gypsum board panels are
relatively large compared to other materials. They come in 48- and 54-inch wide sheets and in lengths of
8, 10, or 12 feet, so they quickly cover large wall and ceiling areas. Gypsum board assemblies require
only a few tools for their construction. Gypsum board can be cut with either a utility knife or a variety of
saws, and it can be attached with a variety of fasteners, including screws, nails, and staples. It can also
be adhesively attached to many substrates. Gypsum board is a lightweight material. Two workers can
easily handle most panels and cover large areas in very short time periods. Gypsum board is easily
finished using either a few hand tools or relatively modest machines. Gypsum board installers can
quickly learn most application techniques in a few hours.
6. ADVANTAGES OF GYPSUM BOARD CONSTRUCTION
2. Fire resistance
Gypsum board is an excellent fire-resistive building material
3. Sound isolation
Preventing the transfer of unwanted sound to adjoining areas is a key consideration when designing a
building, specifically when taking into account the intended activities of the occupants in the various
parts of the building. Gypsum board wall and ceilings systems effectively help control sound
transmission.
4. Durability
Gypsum board is used to construct strong, high quality walls and ceilings that offer excellent
dimensional stability and durability. Surfaces created using gypsum board are easily decorated and
refinished.
5. Economy
Gypsum board is readily available and easy to apply. It is an inexpensive wall surfacing material that
provides a fire resistant interior finish. Gypsum board building systems can generally be installed at
significantly lower labor costs than most alternate systems.
7. ADVANTAGES OF GYPSUM BOARD CONSTRUCTION
6. Versatility
Gypsum board satisfies a wide
range of architectural
requirements for design. Ease
of application, performance,
ease of repair, availability, and
its adaptability to all forms of
decoration combine to make
gypsum board unmatched by
any other surfacing product.
8. TYPES OF GYPSUM BOARD ACCORDING TO THICKNESS
Using ever-developing new technologies, gypsum producers offer a variety of gypsum board products
for many specific applications, including: the surface layer of interior walls and ceilings; a base for
ceramic, plastic and metal tile; exterior sheathing and soffits; elevator and other shaft enclosures; area
separation fire walls between occupancies; and the fire-resistant layer over structural elements.
Regular and Type X gypsum board (described below) are available in SEVERAL THICKNESSES.
Different thicknesses are typically used in the specific following applications:
¼ -inch – A low cost gypsum board used as a base in a multilayer application for improving sound
control, used to cover existing walls and ceilings in remodeling and for curved surfaces.
5/16 -inch – A specialty product primarily used in the production of manufactured housing and in
laminated double thickness for special sound control panels.
3/8-inch – A gypsum board principally applied in a double-layer system over wood framing and as a face
layer in repair or remodeling.
½-inch – Generally used as a single layer wall and ceiling material in residential work and in double-
layer systems for greater sound and fire ratings.
9. TYPES OF GYPSUM BOARD ACCORDING TO THICKNESS
Standard size gypsum boards are 48 inches wide and 8, 10, 12 or 14 feet
long. The 48 inch width is compatible with standard framing methods in
which studs or joists are spaced 16 inches and 24 inches (Other lengths and
widths of gypsum board are available from the manufacturer on special
order.)
Edges available are rounded, tapered, beveled, square edge, and tongue
and groove (V-edge).
5/8-inch – Used in quality single-layer and double-layer wall systems. The
greater thickness provides additional fire resistance, higher rigidity, and
better impact resistance.
10. TYPES OF GYPSUM BOARD IN ALPHABETICAL ORDER
Abuse-resistant gypsum panels offer greater resistance to surface indentation, abrasion and
penetration than standard gypsum panels.
Eased edge gypsum board, which has a tapered and slightly rounded or beveled factory edge. It may
be used as an aid in custom finishing of joints.
Exterior gypsum soffit board is board designed for use on the undersides of eaves, canopies,
carports, and other commercial and residential exterior applications with indirect exposure to the
weather. Soffit board is available in 1/2 or 5/8 -inch thicknesses with both regular and Type X core.
Foil-backed gypsum board has aluminum foil laminated to the back surface of regular gypsum board
or other gypsum panel products. Foil-backed panels serve as vapor barriers.
Gypsum base for veneer plaster serves as a base for thin coats of hard, high strength gypsum veneer
plaster.
Gypsum liner board serves as a liner panel in shaft walls, stairwells, chase ways, area separation fire
walls, and corridor ceilings. It has a special fire-resistant core .It has a special fire-resistant core
encased in moisture-resistant paper. Liner board is available in ¾ or 1 -inch thicknesses, widths of 24 or
48 inches and with square edges (sometimes eased square edges). Gypsum liner board is also
available with fiberglass mat facing that increases its weather and mold resistance.
11. TYPES OF GYPSUM BOARD IN ALPHABETICAL ORDER
Gypsum sheathing is used as a protective fire resistive membrane under exterior wall surfacing materials such as wood
siding, masonry veneer, stucco and shingles. It also provides protection against the passage of water and wind and adds
structural rigidity to the framing system. The noncombustible core is surfaced with water repellent paper; in addition, it may
also have a water resistant core. Available in 2 feet and 4 feet widths, ½ -inch and 5/8 -inch thick. It is also available with
Type X core. Gypsum sheathing is also available with a glass mat facing. This product is more weather resistant and mold
resistant than paper-faced gypsum sheathing, and it is often used as a substrate for Exterior Insulating Finishing Systems
(EIFS).
Impact-resistant gypsum panels offer greater resistance to the impact of solid objects from high traffic and vandalism than
standard gypsum panels.
Mold-resistant board incorporates various methods of preventing the growth of mold and mildew on the board’s surface.
Non-paper-faced gypsum board is unfaced or has a facing other than paper.
Regular gypsum board (gypsum wallboard) is used as a surface layer on walls and ceilings.
Sag-resistant board is a ceiling panel that offers greater resistance to sagging than regular gypsum products used for
ceilings where framing is typically spaced 24 inches o.c.
Type C or Proprietary Type-X gypsum board is available in ½ -inch and 5/8 -inch thicknesses and is required in some fire
rated assemblies. Additional additives give this product improved fire resistive properties.
Type X gypsum board is available in ½ -inch and 5/8 -inch thicknesses and has an improved fire resistance made possible
through the use of special core additives. It is also available with a predecorated finish. Type X gypsum board is used in most
fire rated assemblies.
12. LIMITATIONS
For installation of gypsum board and finishes, maintain room temperature at not less than 40 degrees F for
the mechanical application of gypsum board and not less than 50 degrees for the adhesive application of
gypsum board and for joint treatment, texturing and decoration, unless recommended otherwise by the
manufacturer.
CAUTION: When using a temporary heat source, do not allow ambient temperatures to exceed 95 degrees F
in any given room or area. Maintain adequate ventilation in the working area during installation and curing
period. Do not use gypsum board where exposure to moisture is extreme or continuous. Take care to ensure
that the gypsum board will not be exposed to temperatures exceeding 125 degrees F for extended periods of
time, for example, when located adjacent to wood burning stoves, electric lighting, electric heating appliances
or other heating units, or hot air flues.
POINTS TO REMEMBER : Do not use water-resistant gypsum board on ceilings or soffits unless extra
framing is installed; do not exceed 12 inches . between framing members. Do not use water-resistant gypsum
board as a tile-backing substrate material where the final surface is directly exposed to running water; select
one of several specialty products, including glass-mat-faced gypsum board or cement-based board, as a tile-
backing substrate for areas directly exposed to running water.
13. APPLICATION OF GYPSUM BOARD
Gypsum board can be applied over wood or metal framing or furring. It can be applied to masonry and
concrete surfaces, either directly or to wood or metal furring strips
When applying board directly to masonry or concrete surfaces, smooth or fill in any irregularities to
ensure proper attachment and an acceptable final finished surface. Furring properly attached to interior
sides of exterior walls provides flat surfaces for standard fastener application as well and sufficient
separation from substrates to overcome dampness in exterior walls. Do not allow gypsum board to
directly contact surfaces, such as concrete or soil, with potentially high moisture contents. Most common
in residential construction is the gypsum wallboard system1in which the joints between the panels and
internal corners are reinforced with tape and covered with joint compound to create a surface suitable
for final decoration. External corners are normally reinforced with either a metal or plastic corner bead
which in turn is covered with joint compound. Exposed edges are covered with metal or plastic trim. The
result is a smooth, unbroken surface ready for final decoration of paint, textures, wallpaper tile, paneling,
or other materials.
14. STORAGE AND HANDLING
Schedule the delivery of gypsum board to coincide with its
installation.
Store boards or panels flat and protected from the elements. Be sure
that materials used as storage supports (risers) are at least 4 inches
in width and of uniform depth or length. As the units of gypsum board
are tiered, align risers carefully from bottom to top so that the load of
each tier is transferred directly to the next level of risers, thus
avoiding sagging or otherwise distorting the plane of the boards.
Avoid stacking longer boards on shorter boards to prevent the longer
boards from warping or breaking. Avoid leaning boards horizontally
against vertical framing as they may shift and fall and in turn injure
workers. Also avoid leaning boards during periods of high humidity or
else the boards may warp. Remove shipping bags immediately after
delivery to prevent the buildup of condensation. Keep materials
protected from the weather until ready for use on the jobsite. Take
care while moving boards not to drag them and damage their edges
and corners.
15. SHRINKAGE
Shrinkage with Reduction in Moisture Content
If framing shrinkage is substantial or nails are longer than
necessary, the gypsum board may separate from its framing
lumber, which often causes nail heads to protrude above the
board surface (these blemishes are colloquially known as
“nail pops”).
16. TOOLS
installation and finishing require only some basic tools. While there are also many specialized hand and power
tools available for gypsum board installation, here’s a list with brief descriptions of the basic tools necessary for
a typical wallboard job:
Measuring tape – A steel retractable measuring tape, usually 25 feet in length.
Gypsum board T-square –Square edge for measuring and cutting gypsum board to length and for cutting out
holes for square outlet boxes and other openings.
Utility knife – Standard cutting tool with replaceable/reversible blades for scoring and cutting gypsum board.
Hammer – Drives nails through gypsum board into wood framing.
Keyhole saw – Small triangular saw for cutting out holes for outlet boxes, pipes, and other penetrations.
Rasp – A tool for smoothing rough edges of wallboard after it has been scored and snapped.
Assorted trowels and taping knives – Bladed tools for applying and smoothing tape and joint compound over
joints and fastener heads.
Mud tray – Box to contain joint compound while finishing joints and fastener heads.
Sanding pole – Tool that enables sanding walls from floor to ceiling and standard height ceilings without the use
17. APPLICATION SEQUENCE
Use the following procedures to ensure a successful gypsum
board application:
1. Install ceiling panels first, then the wall panels.
2. Once cut to size, position gypsum boards into place without
forcing them.
3. Match similar edges and ends, i.e.: tapered to tapered,
square-cut ends to square ends.
4. Plan to span the entire length of ceilings or walls with single
boards if possible to reduce the number of butt joints, which are
more difficult to finish. Stagger butt joints and locate them as far
from the center of the wall and ceiling as possible so they will be
inconspicuous.
18. APPLICATION SEQUENCE
In residential buildings with ceiling heights under 8′1″, wallboard is best installed at right angles
(perpendicular) to framing members as this orientation of the panels leaves fewer joints to finish. On long
walls, horizontally attaching boards of the maximum practical length will minimize the number of butt joints.
Avoid using damaged board.
Carefully measure where board ends and edges will meet corners and ceilings. Accurate measuring reveals
irregularities in framing and furring that require corrective allowances when cutting boards. Correct poorly
aligned framing before attaching To cut gypsum board, working from the face side , first score the board by
cutting through the paper to the core with a sharp knife (Fig. 6).
Fig. 6 – Measuring from Edge before Cutting BoardFig. 8 – Snapping Scored Board
19. SINGLE-PLY / MULTI-PLY APPLICATION
In light commercial and residential construction, single-ply gypsum board systems (Fig. 9) are the most
commonly used wall and ceiling systems. Usually such systems meet fire resistance and sound control
requirements2. Multi-ply systems (Fig. 10) have two or more layers of gypsum board that will typically
increase sound isolation and fire resistive performance. Multi-ply systems also provide better surface
quality because face layers are often laminated over base layers, so fewer fasteners are needed to
attach the face layer. As a result, surface joints of the face layer are reinforced by the continuous base
layers of gypsum board. Nail popping and joint ridging problems are less frequent, and imperfectly
aligned supports have less effect on the finished surface.
Sever the board’s backing paper by snapping the board in the reverse direction or by cutting the backing
paper with a scoring knife. Gypsum board may also be cut using a hand saw. Smooth all cut edges and
ends of the gypsum board to form neat, tight-fitting joints when installed. Smooth ragged ends or broken
edges with a rasp or sandpaper, or trim them with a sharp knife. If burrs on the cut ends are not
removed, they will form visible ridges in the finished surface
