Optimum Roof Overhang

Overhangs are most effective for south facing elements in the northern hemisphere and at midday.

Optimum roof overhang.

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. Doing so keeps basements and crawlspaces dry and it also helps to. 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. For high wind resistance use 7 16 inch or 19 32 inch plywood or osb roof decking attached with nails not staples. 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. Optimum overhang dimensions for energy saving 295 sun fig.

Roof construction and materials considerations roof decking. But are they really necessary. Roof and overhang systems should be designed to resist wind uplift especially in hurricane prone regions. You can use the free software sketchup to draw the house and it will draw sun shadows for any date time at your location.

24 dec 2012 02 45 pm. The optimum depth varies with the latitude and the type of climate. Borst passive solar roof overhang design calculator. How roof overhangs work.

Roof overhangs should be no more than 2 feet wide. Those larger than 2 feet wide have to withstand very high uplift so they should be engineered. Roof overhangs might look relatively routine but there is a lot of design thinking that goes into creating the optimal dimensions for each one. An important component of passive solar design is calculating building openings doors and windows and roof overhangs.

For instance several features of a window will influence gain of solar heat and shade. Roof overhangs at the eaves and rakes protect the walls below from rain and sun. There isn t general rules to size an overhang. They are essential for framing and shading windows reducing splashback and getting rain to fall far enough away from the foundation.

Figure 2 illustrates how this is possible. Borst engineering construction llc competence integrity and professionalism are integral to all that we do. Geometry of overhang separated from top of window.