Flat Roof Slope Requirement

The short simple answer is 2 12 has traditionally been considered the absolute minimum acceptable roof slope suitable for asphalt shingles.

Flat roof slope requirement.

Pitches between 8 12 and 10 12 33 40 are also considered walkable but it is not advisable and if you have to walk on these roofs extreme caution should be. This means that the rise of the slope goes up or down 8 inches for every 12 inches. Asphalt shingles require a minimum roof pitch of 2 12 or greater. Metal roof shingles require a minimum roof pitch of 3 12 or greater.

The minimum roof slope allowed by code for any type of roof is in 12 applicable only to coal tar pitch roof systems. This 1 4 12 minimum roof slope requirement also applies to spray polyurethane foam spf roof systems in new construction. In order to achieve this drop a slightly steeper angle of 1 40 1 44 should be the aim when installing a flat roof as this accounts for surface. Normally 1 80 0 72 is the recommended minimum angle for a slope and this is universal across the vast majority of flat roofing systems regardless of the materials that they incorporate.

For standing seam metal roof panel systems a 1 4 12 minimum roof slope is prescribed. Let us recap on the minimum roof pitch required for each type of roofing material. Asphalt shingles continue to be the most widely installed roof covering option in north america. In general the minimum slope for a flat roof is 1 0 but as stated earlier this is only possible in theory.

A roof pitch of 6 12 26 5 or less is considered easily walkable and no extra precautions are required. Since they vary in quality as well as method of installation the choice preferred for a flat roof will ultimately have an effect on the final slope of the flat roof. For metal panel roof systems with nonsoldered seams with applied lap sealant ibc 2018 prescribes a 1 2 12 minimum roof slope. Cold roofs and warm roofs.

Cold roofs have the waterproof layer placed directly onto the roof deck and the insulation inside the roof just above the ceiling. A roof of pitch 7 12 30 is manageable but caution should be taken. To put it in perspective the angle of this slope would be around 30 degrees. They provide excellent weather resistance great value and now more than ever a tremendous range of beautiful designs and color blends.

In this case ventilation is required and the roof can still become wet with condensation which may cause materials to decay. The minimum pitch for a roof is 1 4 12 which translates to 1 4 inch rise to 12 inches of run. There are two types of flat roof. The following table provides the minimum required allowable roof slope for each type of roofing material mentioned in the code.

Clay and concrete tile requires a minimum roof pitch of 2 1 2 12 or greater.