Optimum Roof Overhang

Roof overhangs might look relatively routine but there is a lot of design thinking that goes into creating the optimal dimensions for each one.

Optimum roof overhang.

Those larger than 2 feet wide have to withstand very high uplift so they should be engineered. Roof overhangs should be no more than 2 feet wide. Geometry of overhang separated from top of window. With composite siding such as boral s truexterior siding over a ventilated rain screen and with properly executed flashing at the windows and doors the walls on the fhb house will be able to handle rain just fine.

Borst passive solar roof overhang design calculator. How roof overhangs work. Jonr senior member posts 5341. 24 dec 2012 02 45 pm.

Optimum overhang dimensions for energy saving 295 sun fig. Borst engineering construction llc competence integrity and professionalism are integral to all that we do. If the building element bears more than about 30 off true south the effectiveness of an overhang as with any solar feature begins to decrease significantly. Oversized overhangs can increase the risk of roof or truss uplift.

180tan 10 in order to estimate the radiation received by windows with overhangs the beam diffuse and reflected com ponents of irradiance must be estimated as functions of time and day of the year. The size of the window width and height and the window s relationship to the roof the space above the window influences the direct. Roof and overhang systems should be designed to resist wind uplift especially in hurricane prone regions. They are essential for framing and shading windows reducing splashback and getting rain to fall far enough away from the foundation.

There isn t general rules to size an overhang. But are they really necessary. Roof construction and materials considerations roof decking. Figure 2 illustrates how this is possible.

Doing so keeps basements and crawlspaces dry and it also helps to. Overhangs are most effective for south facing elements in the northern hemisphere and at midday. Roof overhangs a roof overhang is a simple architectural feature which can be used on the south side of the house to block direct sunlight in summer without reducing the available sunlight in winter. For high wind resistance use 7 16 inch or 19 32 inch plywood or osb roof decking attached with nails not staples.

Roof overhangs at the eaves and rakes protect the walls below from rain and sun. Because the sun travels a higher path in the sky in the summer than in winter the overhang blocks. You can use the free software sketchup to draw the house and it will draw sun shadows for any date time at your location.