Page 321 - directory final 2014/2015

Construction Consultants

U

ULTRAVIOLET - The invisible rays of the spectrum of light which are at its violet end. Sometimes abbreviated U.V.

UPRIGHTS - Vertical members supporting the sides of a trench.

U-VALUE – A measure of air-to-heat transmission (loss or gain) due to the thermal conductance and the difference in indoor

and outdoor temperatures. As the U-value decreases, so does the amount of heat that is transferred through the glazing mate-

rial. The lower the U-value, the more restrictive the fenestration product is to heat transfer. Reciprocal of R-value.

V

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 RETARDER (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.

VEINING – In roofing, the characteristic lines or “stretch marks” which develop during the aging process of soft bitumens.

VENT PIPE - A vertical pipe of relatively small dimensions which protrudes through a roof to provide for the ventilation of

gasses.
320 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.

VENT STACK - A vertical vent pipe installed for the purpose of providing circulation of air to and from any part of a drain-

age system.

See page 321

Chamber of Construction Industry Sri Lanka Service Providers