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Flooring
A rough floor that forms the base for a finished floor is known as a “subfloor”. The subfloor is
usually “plywood” that is laid over "floor joists" (beams) to support it. Then, different types
of flooring such as hardwoods, carpeting, tile, etc. is laid over the subfloor. The following are
some flooring terms you should understand:
• Plywood - A panel (normally 4' X 8') of wood made of three or more layers of veneer,
compressed and joined with glue, and usually laid with the grain of adjoining plies at right
angles to give the sheet strength.
• Roll, rolling – To “roll the floor” means to install the floor joists.
• T & G – A joint made by a “tongue” (a rib on the edge of a board) that fits into a
corresponding groove in the edge of another board to make a tight flush fit. Typically, the plywood used for the subfloor is T & G.
• Toe Nailing – To drive a nail in, at a slant. This is the method used to secure floor
joists.
Calculate the Square Yardage of Carpeting
To calculate the square yardage for carpeting and padding, the simplest method is to calculate the square footage of the room(s) (length x width) and divide by 9. However, many
contractors add 5% to the square footage of the room to allow for seams.
Simple Method Example: A contractor would like to calculate the square yardage for
carpeting the padding for a 12 x 12 room.
12 x 12 = 144 square feet ÷ 9 = 16 square yards
Add 5% Method Example: A contractor would like to calculate the square yardage for
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including dormers. Then, multiply length x width to get the square footage of each plane. Simply
add the square footage of each of the planes together to derive the total square footage of your
roof.
For example, this shed roof has one roof plane. Simply measure length (A) x width (B) -
A x B = 120' x 100' = 12,000 sq. ft. for the total square footage of the roof.
This gable roof has two planes. So, multiply length (A) x width (B) to get the square footage for
each plane, then add the two planes together to derive the total square footage of the roof -
• Plane 1 - 120' x 100' = 12,000 sq. ft.
• Plane 2 - 120' x 100' = 12,000 sq. ft.
• Plane 1 + Plane 2 = 24,000 sq. ft. for the total square footage of the roof.
Roof surfaces are measured in "squares." A "square" is an area of roof which measures 100 square feet. To determine the number of squares on the gable roof above, for example, simply
divide its total of 24,000 square feet by 100. Which means you will need 240 "squares" of
shingles to cover it.
The most common type of shingle, called a three-tab or strip shingle, is generally
packaged three bundles per square. There are 29 (12 x 36 in) shingles in each bundle.
If this is a new roof, you will also need 240 squares of underlayment (no underlayment is
needed if you are applying shingles directly over an existing asphalt roof). Underlayment usually
comes in rolls of four squares each, so covering 240 squares would require 60 rolls of
underlayment. Be sure to add 10% to all your material totals for trim allowance.
Slope
You will also need to know the slope of your deck. In order to determine this, measure the
vertical rise of your deck in inches over a 12" horizontal distance. If this rise is 4", then your
roof slope is 4 in 12. Roof slopes are always expressed with the vertical rise mentioned
first and the horizontal run (12") mentioned second.
Steep Roofs
To measure a steep roof, you will have to use an alternate method. To obtain the roof length,
measure the exterior walls plus the overhang for the length of the house parallel to the ridge.
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Roof Angles
Glossary of Roofing Terms
American method - Application of giant individual shingles with the long dimension parallel
to the rake. Shingles are applied with a 3/4-inch space between adjacent shingles in a course.
ASTM - American Society for Testing and Materials - A voluntary organization concerned with development of consensus standards, testing procedures and specifications.
Asphalt - A bituminous waterproofing agent applied to roofing materials during
manufacturing.
Asphalt plastic roofing cement - An asphalt-based cement used to bond roofing materials.
Also known as flashing cement or mastic; should conform to ASTM D-4586.
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to the circuit. If a person has become the ground for the leaking current, the person will still
get a shock, but the GFCI will prevent the shock from being fatal.
Wiring Types and Methods
Wiring types and methods significantly affect the cost of materials and amount of labor required
for repairs. Following are the most common types of wiring used to in residential construction.
• Rigid conduit
• Thin wall conduit
• Nonmetallic sheathed cable
• Armored cable
Wiring comes in two types - two wire and three wire. In a 2-wire strand, there is no ground
wire. There is only a black wire that has current in it (referred to as the “hot” wire) and a
white wire that is neutral. In a 3-wire strand, there is a green or bare copper wire in addition to
the hot wire and the neutral wire. The green or copper wire is the ground wire.
Rigid conduit is similar to water piping and is usually used outside or underground. It comes in
ten-foot lengths and various inside diameters. The pipe is threaded for coupling and connecting
to boxes. Conduit systems are installed before the wiring is threaded through them.
Thin-wall conduit is similar to rigid conduit in many ways. It is available in ten-foot lengths and
the same inside diameters. However, because it can be easily cut and bent because it has
compression fittings rather than threaded ones, thin-wall conduit is far more popular than rigid
for residential electrical applications. Another name for thinwall conduit is electrical metallic
tubing (EMT). Thin-wall conduit can also be nonmetallic.
Nonmetallic sheathed cable is one of the most popular methods of electrical wiring. It is both
less expensive than conduit and less time-consuming to install. Unlike the conduit systems, in
which wires are run after the tubing has been installed, nonmetallic sheathed cable is made up of individual plastic coated wires and a bare ground wire all wrapped in a flame-retardant, water
resistant plastic sheath. Connections must be made in metal or plastic junction boxes. Many
local building codes prohibit the use of nonmetallic sheathed cable in some types of residential
construction.
Armored cable is commonly called “BX cable”. Armored cable is not used as often as it once
was because of nonmetallic sheathed cable’s popularity. Armored cable consists of two or more
insulated wires encased in a spiral steel sheath. Like the other forms of wiring described, BX
has special connectors and fittings.
Structured Wiring
Most commercial buildings and many new homes are built with structured wiring to
accommodate audio, video, and data technology. Structured wiring (also known as
infrastructure wiring) consists of the wiring and components used for telephones, fax machines,
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computers, the Internet, audio equipment, security cameras, and video equipment such as cable
or satellite TV. Commercial properties often used fiber-optics cables to transmit data. Some
communities are installing fiber-optic cable so that residents can enjoy high-definition television.
Damage
Residential electric systems can be damaged by various causes, but fire, lightning and power
surges are the most common. The extent of damage varies by the type of electrical wiring.
Plastic sheathed cable can withstand less heat than metal conduit. Building inspectors often
require complete rewiring after a loss when it is not necessary. Adjusters should consider employing an electrical engineer or qualified contractor for an expert opinion, thus resolving
disputes and satisfying the building inspector. Likewise, upgrades may be required by code. If
this situation occurs, the adjuster must be aware of the potential coverage issue that it raises.
Glossary of Electrical Terms
Alternating Current (AC) – A flow of electric charge that undergoes periodic reverses in
direction. In North America, ordinary household current alternates at a frequency of 60 times
per second.
Ampere (A or Amp) - Unit of electrical current. Either how much electricity an appliance
will use, or a circuit (fuse, mcb, cable, connectors etc.) can handle. Fuses are always rated by
current as are cables. Each appliance will have an Amp rating or if only a wattage is quoted,
Amps = Wattage/Voltage.
Circuit Breaker - A switch like device with a pre-set current limit used to protect a circuit
from electrical overload. If the circuit breaker is activated (or tripped), it can be reset by
pushing a button - however the reason for the trip should always be investigated as it is an
indication of an overload, possible some form of fault.
Circuit Protective Conductor (CPC) - A name used for the protective earth wiring of all
metal parts of a building (see Earthing).
Conduit - A pipe or tubing used to house cable. In walls to switches and socket usually oval
and plastic in modern houses, or round and metal in older ones.
Direct Current (DC) - Unlike Alternating Current, the flow of electricity does not alternate,
it flows in just one direction. Normally used in low voltage electronic circuits and computers
etc. around the house and is usually derived from the alternating mains via a power supply.
Double Pole Switch - A switch which breaks (or makes) both the live and neutral lines with
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Voltage (V) - The numerical value of the electrical potential between two points in a circuit.
Volts = Wattage/Amperes.
Wattage (W) - A unit of power - in electrical equipment defined as Watts = Volts x
Amperes. One watt is fairly small and household equipment will often be rated in terms of
Kilowatt (kW) - 1kW = 1000W.
Interior Construction
Most construction projects today use “drywall” instead of plaster to finish interiors walls. Drywall construction is a technique in which the interior wall finish is applied in a dry condition,
generally in the form of sheet materials or wood paneling.
“Sheetrock” (drywall, wall board or gypsum) are used to finish the interior walls of a
structure. Sheetrock is a manufactured panel made of gypsum plaster and encased in thin
cardboard. It is usually ½ inch think and comes in sizes 4 ft. x 8 ft. or 4 ft. x 12 ft.
“Green board” type sheetrock has a greater resistance to moisture than regular white
sheetrock and is used in bathrooms and other wet areas.
The joints between the sheetrock boards are covered by “taping” using paper tape and joint
compound, sometimes called mud.
Measuring Sheetrock (Drywall)
To measure how much sheetrock (drywall) needed for a room, you must calculate the square
footage of the room, and add the ceiling. For example, we have a 10 x 10 room with 8 ft high
ceilings so each wall would be 80 square feet. Then, we will multiply the square footage of
each all by 4 (because we have 4 walls), leaving us with 320 square feet. A 10 x 10 room would have a ceiling that is 100 square feet, so we add this to 320, to reach 420 square feet. The
sheets of drywall come in either 4 x 8 (32 square feet) or 4 x 12 (48 square feet).
If we purchase the 4 x 8 sheets, we would divide 420 by 32, we get 13.125, therefore we
would need to purchase 14 sheets of drywall.
If we purchase the 4 x 12 sheets, we would divide 420 by 48, we arrive at 8.75, or 9
sheets of drywall would need to be purchased.
Painting
When estimating the amount of paint to purchase, calculate the square footage of the room.
One gallon of paint is needed to cover between 350 and 400 square feet of finished walls
if rollers and brushes are used. A paint sprayer will use about 10% more paint.