Domestic roof construction
[2] 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.
Tie beams, which may also serve as ceiling joists, are typically connected between the lower ends of opposite rafters to prevent them from spreading and forcing the walls apart.
In the United States, building codes specify the loads in pounds per square foot which vary by region.
The covering is also a major element of the architecture, so roofing materials come in a wide variety of colors and textures.
Some roofing materials help reduce air conditioning costs in hot climates by being designed to reflect light.
Asphalt shingles dominate the North American residential roofing market, because they are typically less expensive[6] compared to other materials.
In the southern US and Mexico, clay tile roofs are also very popular, due to their longevity, and ability to withstand hurricane winds with minimal or no damage.
Without proper ventilation, humidity can cause interstitial condensation within the roof fabric; this can lead to serious structural damage, wet or dry rot, and can ruin insulation.
Most building materials are permeable to water vapour; brick, concrete, plaster, wood and insulation all can fall victim to interstitial condensation.
[14] Over these boards they then firmly secured in place a matting material made of natural plant fibers woven together, such as cane reeds, leaves of rush or papyrus, palm fronds and tree bark.
[14] In Sanaa, Yemen, in the early 20th-century, twisted mats of palm-leaves were laid over wooden beams used to support the ceilings.
[18] The Colchians in Pontus made their roofs by "cutting away the ends of crossbeams, and [by] making them converge gradually as they lay them across, they bring them up to the top from the four sides in the shape of a pyramid.
[18] The ancient Phrygians built a pyramidal roof of logs fastened together, and covering them over with reeds and brushwood, upon which was heaped up very high mounds of earth.
