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V
Vacuum Breaker:
An anti-siphon device that prevents waste water
from being drawn back into supply lines, potentially
contaminating the
water supply. A type of backflow preventer.
Valley:
The internal angle formed by the junction of two
sloping sides of a roof.
Valley
Rafter: A rafter that forms the intersection of
an internal roof angle. The valley rafter is normally made
of double 2-inch-thick
members.
Valley
Shield: A quality underlayment for added protection
in the heavy water flow areas of a roof. This self adhering
product has a
waterproof asphalt
coating which offers excellent elongation and recovery properties
for accommodating roof expansion and
contraction and
structural movement.
Valuation:
An inspection carried out for the benefit of the
mortgage lender to ascertain if a property is a good security
for a loan.
Valuation
Fee: The fee paid by the prospective borrower
for the lender's inspection of the property. Normally paid
upon loan
application.
Valve:
A device to stop, start or regulate the flow of
liquid or gas through or from piping.
Vapor:
The gaseous form of any substance.
Vapor Barrier:
A membrane which is placed between the insulation
and the roof deck to retard water vapor in the building
from
entering the insulation
and condensing into liquid water.
Vapor Retarder:
Any substance that prevents the transmission of
water vapor.
Variable
Rate: An interest rate that will vary over the
term of the loan.
Varnish:
A thickened preparation of drying oil, or drying
oil and resin suitable for spreading on surfaces to form
continuous,
transparent coatings,
or for mixing with pigments to make enamels.
Vehicle:
The liquid portion of a finishing material; it
consists of the binder (non-volatile) and volatile thinners.
Veining:
In roofing, the characteristic lines or "stretch
marks" which develop during the aging process of soft
bitumens.
Veneer:
Thin sheets of wood made by rotary cutting or
slicing a log.
Vent:
A pipe or duct which allows flow of air as an inlet or outlet.
Vent Pipe:
A vertical pipe of relatively small dimensions
which protrudes through a roof to provide for the ventilation
of gasses.
Vent Stack:
A vertical vent pipe installed for the purpose
of providing circulation of air to and from any part of
a drainage system.
Vent System:
In plumbing, a system to provide a flow of air
to or from a drainage system or to provide circulation of
air within such
system to protect
traps seals from siphonage and back pressure.
Ventilator:
Device installed on the roof for the purpose of
ventilating the interior of the building.
Venting:
The process of installing roof vents in a roof
assembly to relieve vapor pressure. The process of water
in the insulation
course of the roof
assembly evaporating and exiting via the roof vents.
Vermiculite:
An aggregate somewhat similar to perlite that
is used as an aggregate in lightweight roof decks and deck
fills. It is
formed from mica,
a hydrous silicate with the ability of expanding on heating
to form lightweight material with insulation quality.
Used as bulk insulation
and also as aggregate in insulating and acoustical plaster
and in insulating concrete.
Vertical:
Being or situated at right angles to the horizon;
upright.
Veterans
Administration (VA): A federal agency that insures
mortgage loans with very liberal down payment requirements
for
honorably discharged
veterans and their surviving spouses.
Viscosity:
The internal frictional resistance offered by
a fluid to change of shape or to the relative motion or
flow of its parts.
Visible
Light Transmittance: The percentage of visible
light (390 to 770 nanometers) within the solar spectrum
that is transmitted
through glass.
Visqueen:
A 4 mil or 6 mil plastic sheeting.
Visual
Mock-Up: Small scale demonstration of a finished
construction product.
Vitreous
China: A non-porous ceramic that is coated with
a ceramic glaze to form toilets and lavatories.
Void:
A cardboard rectangular box that is installed between the
earth (between caissons) and the concrete foundation wall.
Used
when expansive
soils are present.
Volatile
Thinner: A liquid that evaporates readily and
is used to thin or reduce the consistency of finishes without
altering the
relative volumes
of pigment and non-volatile vehicles.
Voltage:
The driving force behind the flow of electricity
somewhat like pressure is in a water pipe. Most homes are
wired with '110'
and '220' volt
lines. The '110' volt power is used for lighting and most
of the other circuits. The '220' volt power is usually used
for the kitchen stove, water heater and dryer. (The terms
'110' and '220' volts are a short hand, e.g. a '110' volt
line is usually rated at
117 volts plus
or minus 10%).
Voltmeter:
Measures the voltage flowing through a circuit.
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