Flat Roof Slope Requirement

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.

Flat roof slope requirement.

They provide excellent weather resistance great value and now more than ever a tremendous range of beautiful designs and color blends. In general the minimum slope for a flat roof is 1 0 but as stated earlier this is only possible in theory. Metal roof shingles require a minimum roof pitch of 3 12 or greater. In this case ventilation is required and the roof can still become wet with condensation which may cause materials to decay.

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. The slope of a roof or pitch is determined by how many inches the roof rises over 1 foot or 12 inches. For standing seam metal roof panel systems a 1 4 12 minimum roof slope is prescribed.

The short simple answer is 2 12 has traditionally been considered the absolute minimum acceptable roof slope suitable for asphalt shingles. Asphalt shingles continue to be the most widely installed roof covering option in north america. Cold roofs and warm roofs. There are two types of flat roof.

An example for a steep sloped roof is 8 12. The minimum pitch for a roof is 1 4 12 which translates to 1 4 inch rise to 12 inches of run. The following table provides the minimum required allowable roof slope for each type of roofing material mentioned in the code. However you can only use this pitch with built up roofing or specialized synthetic roofing.

To put it in perspective the angle of this slope would be around 30 degrees. A roof pitch of 6 12 26 5 or less is considered easily walkable and no extra precautions are required. Let us recap on the minimum roof pitch required for each type of roofing material. Asphalt shingles require a minimum roof pitch of 2 12 or greater.

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

Cold roofs have the waterproof layer placed directly onto the roof deck and the insulation inside the roof just above the ceiling.