There are two types of flat roof.
Flat roof slope requirement.
A roof of pitch 7 12 30 is manageable but caution should be taken.
They provide excellent weather resistance great value and now more than ever a tremendous range of beautiful designs and color blends.
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.
In this case ventilation is required and the roof can still become wet with condensation which may cause materials to decay.
The minimum roof slope allowed by code for any type of roof is in 12 applicable only to coal tar pitch roof systems.
In general the minimum slope for a flat roof is 1 0 but as stated earlier this is only possible in theory.
The slope of a roof or pitch is determined by how many inches the roof rises over 1 foot or 12 inches.
The following table provides the minimum required allowable roof slope for each type of roofing material mentioned in the code.
The minimum pitch for a roof is 1 4 12 which translates to 1 4 inch rise to 12 inches of run.
An example for a steep sloped roof is 8 12.
For metal panel roof systems with nonsoldered seams with applied lap sealant ibc 2018 prescribes a 1 2 12 minimum roof slope.
Asphalt shingles continue to be the most widely installed roof covering option in north america.
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.
Metal roof shingles require a minimum roof pitch of 3 12 or greater.
This 1 4 12 minimum roof slope requirement also applies to spray polyurethane foam spf roof systems in new construction.
The short simple answer is 2 12 has traditionally been considered the absolute minimum acceptable roof slope suitable for asphalt shingles.
Let us recap on the minimum roof pitch required for each type of roofing material.
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.
To put it in perspective the angle of this slope would be around 30 degrees.
Clay and concrete tile requires a minimum roof pitch of 2 1 2 12 or greater.
For standing seam metal roof panel systems a 1 4 12 minimum roof slope is prescribed.
A roof pitch of 6 12 26 5 or less is considered easily walkable and no extra precautions are required.
Cold roofs and warm roofs.
However you can only use this pitch with built up roofing or specialized synthetic roofing.
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.
