Drywall Powerpoint0

7/28/2019 Drywall Powerpoint0

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Lather

Lathers assemble and install the framework for gypsum

materials in buildings. These materials include drywall and

plaster.


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Plaster and plastering

There are quite a few plasters but two main types - gypsum based and cement

based.

1. Cement based are used mainly for outdoors.

2. Gypsum based plasters are used indoors only - dampness will attack a gypsum

based plaster and cause it to crumble.

Cement based plasters can be used indoors for areas that are likely to become dampand areas that require a greater thickness of cover.

Gypsum based plaster is used in conjunction with drywall to cover the interior

walls of our homes. This plaster can be found as a powder which must be mixed

with water, or premixed and ready for use.


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What is Drywall?

Drywallsometimes called wallboard, plasterboard, or the brand name

Sheetrockis comprised of a core of wet gypsum rock that is sandwiched

between two sheets of heavy paper. When the gypsum core sets and dries,

the finished product is rigid and sturdy enough for use as a building

material. Drywall is called such because it is a dry alternative to the

previously used lath and plaster method of wall construction, where plasterwas spread over wood formers while still wet. Drywall is faster, less labour

intensive, and cheaper to install than plaster.


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Drywall sizes

Standard drywall comes in sheets that are four feet wide, with lengths of

eight, ten, or twelve feet. Commercial builders often use sheets up to sixteenfeet in length. These large sheets make for quicker installations, because they

reduce the number of joints (seams) between the sheets that need to be filled and

finished.


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Panel thickness:

5/8 inch panel-

considered fire resistant. Even though drywall generally does not burn, 5/8 inch

drywall is used as a firewall. For example, a house that has an adjoining

apartment, 5/8 inch drywall must be used on the wall that the two residencesshare (common wall), and acts as a fire wall. It prevents the fire from spreading

from one residence to the other.

1/2 inch panel-

most commonly used. General purpose for walls and ceilings.


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Types of Drywall

Dent resistant - found in 1/2 inch or 5/8 inch. Much more durable than

regular drywall. Used in high traffic areas, childrens

playrooms, garage, etc.

Sag resistant- found in 1/2 inch panels. Will not sag like some other

1/2 inch panels.

Good to use on ceilings.


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Sound control board- used to reduce sound and also offers higher

thermal insulation. Found in 1/2, 5/8, 3/4 inch

panels.

Cementious backerboard- cement product reinforced with fiberglass

mesh. Used on walls that may be exposed to

water, such as showers.


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Fasteners

Screws

1. Type W bugle head screws

- has a course thread and provides excellent holding power in wood.

2. Type S bugle head screws

- has a tip that drills its own hole in metal studs in walls.

3. Backerboard screws

- made from stainless steel or steel that is non-corrosive


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Fasteners contd

nails

- both smooth and ringshank nails are used. The smooth nails do not hold the

drywall as secure as the ringshank nails. The rings on the shank of the nail gets abetter grip in the wood, thus decreasing the number of nail pops (when the nail

starts to come back out of the drywall).


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Once the drywall has been secured to the wall studs, the seams or joins are

to be covered with plaster before the paint is applied. Before the plaster

can be applied to the joins, it must be covered with tape or beads. Tape

and beads come in a variety of types:

1. Flexible paper tape:

Usually has a seam running along its length so that it can be folded to be

used in corners. Tends to be more time consuming because it has to be

embedded in a coat of plaster.


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2. Fiberglass mesh tape:

Usually self sticking. Its not necessary to apply a coat of plaster underneath it.

3. Composite and metal tapes:

Since these tapes are rigid, it makes it much easier to get a straight crisp inside

corner.

4. Bullnose and metal corners:

These enable you to create a straight and neat outside corner. The metal corner

is a 90 degree angle, whereas the bullnose corner is rounded.

Plaster must be applied to the edges of both inside and outside corners so that it

appears seamless once painted.


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Tapes


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Common Drywall Tools

1. Utility knife: used for cutting drywall.

2. Drywall Saw: used for making cut-outs in the drywall

(circular, rectangular, etc.)

3. Metal snips: use for cutting metal corner beads.


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4. Screwgun: used for inserting screws into the drywall and studs. It is

different from other power drills because it limits the

depth that the screw goes into the drywall.

5. Trowels and taping knives: used to spread the plaster over the

drywall joins.


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6. Sanders: used to smooth the plaster before paint is applied.


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7. Water filter system: consists of a vinyl hose connected to a vacuum

cleaner on one end and a bucket on the other

end with water in it. Another hose leaves the

bucket and attaches to a sander. The idea is for

the dust from the sander to be vacuumed into t

he bucket depositing the plaster dust into the

water and not affecting the vacuum.


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Installing drywall on ceilings and walls

Drywall is always fastened to the ceiling before the walls. This ensures

that the drywall that goes on the wall is underneath the ceiling drywall

and helps to support the drywall thats on the ceiling.

Drywall is fastened to the studs of the walls. Studs are spaced either 16

inches or 24 inches on center. The studs provide the strength for the wall.

16 inch

centers24 inch

centers


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Ceiling


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Walls


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Plastering Seams and Joins

The following is the sequence of events that is usually followed when

plastering a join between two pieces of drywall:

1. If tape is being used, run a coat of plaster on the join.


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2. Place a piece of tape over the plaster, along the full length of the join.


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3. Drag the plaster knife along the tape to allow the excess plaster to

squeeze out. Be careful not to tear the tape. Allow to dry.


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4. Apply a wider coat of plaster over the tape with a plaster knife. Allow to

dry.


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dry.

5. Apply a third coat of plaster over the dry coat with a larger plasteringknife, feathering the edges (thinning the edges).


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The following is the sequence of events that is usually followed whenplastering a join between two pieces of drywall:






dry.

5. Apply a third coat of plaster over the dry coat with a larger plasteringknife, feathering the edges (thinning the edges).

6. Sand with fine sandpaper to smooth irregularities in preparation for

primer and paint.


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Plastering

Profile of layers

First coat over tape Second coat Third coat

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