The international codes i codes are the widely accepted comprehensive set of model codes used in the us and abroad to help ensure the engineering of safe sustainable affordable and resilient structures.
Maximum roof pitch building regulations.
If a roof increases in height by four inches for every foot of horizontal run it is considered to have a 4 in 12 pitch or just a 4 pitch.
Asphalt shingles require a minimum roof pitch of 2 12 or greater.
One ply of smooth roll roofing complying with astm d 6380 and at least 36 inches wide or valley lining as described in items 1 and 2.
For closed valleys valley covered with shingles.
Modern tiles permit shallow pitch but some of the older traditional coverings such as hand made clay tiles require quite steep slopes to ensure rain does not penetrate the roof covering.
Clay and concrete tile requires a minimum roof pitch of 2 1 2 12 or greater.
Although building codes do not directly prescribe maximum allowable roof slopes fire classifications which are required by code often do include maximum roof slope limitations.
These factors include the pitch of the roof the type of slate being used the size of the lap the size of the slate as well as the site s exposure rating.
Let us recap on the minimum roof pitch required for each type of roofing material.
Pitch roof this is where tiles or slates are used and a void is usually created underneath.
Talk in terms of pitches and you will always be understood in the roofing universe.
It may also be influenced by the nature of the roof covering.
For example some epdm membrane assemblies have maximum roof slope limitations as low as 1 2 12.
With regards to the pitch the building standard code bs 5534 recommends a minimum pitch of 200 for slate roofs.
Metal roof shingles require a minimum roof pitch of 3 12 or greater.
Flat roof this usually consists of felting which has a slight fall to allow rain water to drain off.
Asphalt shingles continue to be the most widely installed roof covering option in north america.
Thatch is used occasionally on new dwellings and demands a roof pitch of at least 45 and more likely 50 to allow the rain to flow off quickly and prevent ingress.
The angle of the pitch may be dictated by aesthetic or structural factors.
To enable compliance with the requirements of the building regulations to be demonstrated full details of the new roof will be needed including.
The international code council icc is a non profit organization dedicated to developing model codes and standards used in the design build and compliance process.
