Roof Pitch For Rain

A roof is part of the building envelope.

Roof pitch for rain.

Flat roofs are common with industrial buildings boasting wide roof spans and are also popular in dry climates for houses where there is no need for the roof to help disperse rain and snow. The chief reason for having a roof pitch is to redirect water and snow away from the roof and avoid any percolation that might result from stagnation of water on the roof. The characteristics of a roof are dependent upon the purpose of the building that it covers the available roofing. If you are building a new roof however consider the climate to determine the correct pitch and proper materials.

The safest way to determine the pitch of an existing roof is to measure from inside your attic using a level tape measure and pencil. If water does not properly run off of a roof it will begin to seep in causing rot interior damage and possibly dangerous black mold. This will extend the life of your roof. A roof protects a house and porch from snow and rain as well as the heat of the sun.

In fact any roof between rainfall lines b and c will intersect the same amount of rain and therefore have the same catchment area. The steep roof of the tropical papua new guinea longhouse for example sweeps almost to the ground. Looking at the diagram a roof from a to d also intersects the same amount of rain as the main roof. To put it in perspective.

This means that the rise of the slope goes up or down 8 inches for every 12 inches. Even in these arid regions so called flat roofs are still installed with a slight pitch to keep water from pooling on top of the structure. Minimum roof pitch for a covered porch. The high steeply pitched gabled roofs of northern europe are typical in regions of heavy snowfall.

Thus pitch is typically greater in areas of high rain or snowfall. But what is really interesting it doesn t matter what the roof does to get from point a to point d. The slope of a roof or pitch is determined by how many inches the roof rises over 1 foot or 12 inches. The steeper a roof s pitch the more windblown rain it can collect.

Hold one end of the level against the roof level it and then measure the distance between the roof and the underside of the level at its midpoint which gives you a 12 inch run. The purpose of pitching a roof is to enable water and snow to run off so the greater the amount of rain and or snow an area receives the greater the amount of pitch needed for the roof. A 5 inch gap for instance is a 5. You can measure pitch with a 2 foot level and a tape measure.

A roof is the top covering of a building including all materials and constructions necessary to support it on the walls of the building or on uprights providing protection against rain snow sunlight extremes of temperature and wind.