The short simple answer is 2 12 has traditionally been considered the absolute minimum acceptable roof slope suitable for asphalt shingles.
Minimum gradient for slate roof.
Asphalt shingles continue to be the most widely installed roof covering option in north america.
What does minimum roof pitch mean.
They provide excellent weather resistance great value and now more than ever a tremendous range of beautiful designs and color blends.
Slate shingles can only be installed on roof slopes of 4 12 or greater 33 slope.
In country with heavy snow and tough winter days the metal roof minimum slope is recommended to be 1 12.
Wood shingles minimum roof slope roof pitch r905 7 2.
The slope of a roof is often referred to as the roof s pitch.
It is uncommon to find a roof below 15 but for those very low pitch applications there are interlocking clay pantiles available suitable for use down to 12 5.
It takes the manufacturer s recommendations the unique conditions of the roof as well as the skills and the expertise of the installer to arrive at the right slope.
The minimum roof slope allowed by code for any type of roof is in 12 applicable only to coal tar pitch roof systems.
Sig roofing can supply a number of solutions to cope with these lower pitches such as cambrian roof slate or regent tiles which can be used on pitches as low as.
This means for every 12 horizontal units the roof must rise a minimum of 4 vertical units.
Generally a slate roof is not installed on a pitch less than 4 12.
But since there is still a wide variety of slate roofing systems there are occasions when the minimum pitch can go down to as low as 15 12 5 depending on the design of the roof.
The minimum slope of a roof depends on the roof s profile.
There are some opinions that standing seam metal roof minimum slope is 12 but it increases the possibility of leaking on the few first days of snow arrival.
You need to consider the slope requirements of each panel to determine this minimum slope.
In general the minimum slope for a flat roof is 1 0 but as stated earlier this is only possible in theory.
The profile is the shape taken by the sheets when you bend them to form panels.
As per the nrca roofing and waterproofing manual fifth edition they recommend that roof deck slopes intended for the application of steep slope materials at 4 12 18 degrees or greater page 405.
The following table provides the minimum required allowable roof slope for each type of roofing material mentioned in the code.
Slate shingles minimum roof slope roof pitch r905 6 2.
