Roofing Info For Residents of Atlanta
by Bill Mixon on 05/27/15
The
characteristics of a roof are dependent upon the purpose of the building that
it covers, the available roofing materials and the local traditions of
construction and wider concepts of architectural design and practice and may
also be governed by local or national legislation. In most countries a roof
protects primarily against rain. A verandah may be roofed with material that
protects against sunlight but admits the other elements. The roof of a garden
conservatory, protects plants from cold, wind and rain but admits light.
Domestic roof
construction is the framing and roof covering which is found on most suburban
detached houses in cold and temperate climates. Such roofs are mostly built
with timber, take a number of different shapes, and are covered with a variety
of materials.
The shape of
roofs differs greatly from region to region. The main factors which influence
the shape of roofs are the climate and the materials available for roof
structure and the outer covering.
The basic
shapes of roofs are flat, skillion, gabled, hipped, arched and domed. There are
many variations on these types. Roofs constructed of flat sections that are
sloped are referred to as pitched roofs (generally if the angle exceeds 10
degrees).[2] Pitched roofs, including gabled, hipped and skillion roofs, make
up the greatest number of domestic roofs. Some roofs follow organic shapes,
either by architectural design or because a flexible material such as thatch
has been used in the construction.
Modern timber
roofs are mostly framed with pairs of common rafters or prefabricated wooden
trusses fastened together with truss connector plates. Timber framed and
historic buildings may be framed with principal rafters or timber roof trusses.
Roofs are also designated as warm or cold roof depending on how they are
designed and built with regard to thermal building insulation and ventilation.
The steepness or roof pitch of a sloped roof is determined primarily by the
roof covering material and aesthetic design. roofs actually slope up to approximately
ten degrees to shed water. Flat roofs on houses are primarily found in arid
regions.
In high wind
areas, such as where a cyclone or hurricane may make landfall, the main
engineering consideration is to hold the roof down during severe storms. Every
component of the roof, as of course the rest of the structure, has to withstand
the uplift forces of high wind speeds. This is accomplished by using metal ties
fastened to each rafter or truss. This is not normally a problem in areas not
prone to high wind.