Minimum Flat Roof Overhang

If the roof overhang is not big enough then the only way to protect these windows doors and entryways is by recessing them into the thick exterior wall or by installing special casing and flashing for each door or entryway.

Minimum flat roof overhang.

Figure r804 3 2 1 2 gable endwall overhang. Weather and not properly protected by a roof eave or similar covering table r802 11 required strength of truss or rafter connections to resist wind uplift forcesa b c e f pounds per connection r804 3 2 1 1 eave overhang. This is a compromise you will have to think about the larger the overhang the more pressure your roof will have to withstand. The minimum pitch for a roof is 1 4 12 which translates to 1 4 inch rise to 12 inches of run.

When required testing is in accordance with astm e108 or ul 790. Highly recommend either checking out the program martin linked to or a program like sketchup so that window size and placement can be modelled holistically with overhang design. Eave overhangs shall not exceed 24 inches 610 mm measured horizontally. We are using 9x2 joists for the span but these will be notched down to 5 for the overhang.

Minimum roof fire resistance ratings apply based on the type of construction and some building types do not require a fire rating. The ibc table 1505 1 lists the minimum requirements for roof covering fire resistance classifications a b or c for all types of. Of course it is common in the philippines to build the overhangs larger so to keep the sun off the concrete walls. However you can only use this pitch with built up roofing or specialized synthetic roofing.

We are building the roof and want to create an overhang that acts as a bit of a canopy above a bi fold door to shield it a bit from rain. Overhangs are common in most house designs providing protection against both wind and rain. Metal is usually installed on rafters or strip sheathing rather than the solid decking used under other materials. The larger the overhang the more upward lift will be created on the roof.

The length of the overhang depends primarily on the climate. A typical metal roof overhang may be 2 to 4 inches or even less. Does anyone know what the maximum overhang can be for a flat roof construction depending on joist size. In general roof overhangs offer an effective solution for how to protect windows doors and entryways.

Some slight overhang is recommended in conjunction with a drip edge flashing to prevent water from getting under the roofing and onto underlying wood.