Optimum Roof Overhang

Those larger than 2 feet wide have to withstand very high uplift so they should be engineered.

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. Oversized overhangs can increase the risk of roof or truss uplift. Optimum overhang dimensions for energy saving 295 sun fig. 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.

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. Borst engineering construction llc competence integrity and professionalism are integral to all that we do. Roof and overhang systems should be designed to resist wind uplift especially in hurricane prone regions.

How roof overhangs work. For instance several features of a window will influence gain of solar heat and shade. Because the sun travels a higher path in the sky in the summer than in winter the overhang blocks. The optimum depth varies with the latitude and the type of climate.

Roof overhangs should be no more than 2 feet wide. 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. Jonr senior member posts 5341. You can use the free software sketchup to draw the house and it will draw sun shadows for any date time at your location.

Geometry of overhang separated from top of window. For high wind resistance use 7 16 inch or 19 32 inch plywood or osb roof decking attached with nails not staples. But are they really necessary. 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.

Doing so keeps basements and crawlspaces dry and it also helps to. Borst passive solar roof overhang design calculator. 24 dec 2012 02 45 pm. Roof construction and materials considerations roof decking.

Roof overhangs at the eaves and rakes protect the walls below from rain and sun. Figure 2 illustrates how this is possible. Overhangs are most effective for south facing elements in the northern hemisphere and at midday.