The short simple answer is 2 12 has traditionally been considered the absolute minimum acceptable roof slope suitable for asphalt shingles.
Minimum roof deck slope for the installation of clay tile.
Clay and concrete roof tiles can only be installed on roof slopes of 2 1 2 12 or greater.
About minimum slope allowed for clay tile roofs or other tile roofs if you read through standards such as icc es esr2015 concrete and clay roof tile installation manual for moderate climates copy on file you ll see that there is no prohibition of clay tiles on low slope roofs.
Asphalt shingles continue to be the most widely installed roof covering option in north america.
The minimum roof slope allowed by code for any type of roof is in 12 applicable only to coal tar pitch roof systems.
The irc recommends a minimum pitch of 2 5 12 for these materials.
Clay tiles are colorfast which means their tints improve rather than fade over time.
Traditionally a minimum roof pitch of 20 was recommended in bs 5534 but modern tiles and slates have now been designed for applications as low as 15.
Of the roof deck and additional slope has been provided to.
Clay and concrete tile minimum roof slope roof pitch r905 3 2.
The international residential code irc specifies a minimum 4 12 pitch 4 inches of vertical rise for every 12 inches of horizontal run for a clay or concrete tile roof except that a pitch as low as 2 1 2 12 is allowed when two layers of underlayment are applied.
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.
Over roof edges design and installation of roof drainage sys tems shall comply with section 1503 and the florida building.
The following table provides the minimum required allowable roof slope for each type of roofing material mentioned in the code.
On clay and concrete tile roof coverings shall be in accordance with section 1609 5.
Ratios from that minimum up to 4 12 which are considered low pitch require double underlayment.
Concrete is long lasting with a minimum lifespan of 50 years depending on climate.
Refer to manufacturer s installation instructions frsa tri florida high wind concrete and clay roof tile installation manual fifth edition where the v asd is determined in accordance with section r301 2 1 3 or ras 118 119 or 120 for underlayment and slope requirements for specific roof tile systems.
This article series explains clay tile roofing types clay roofing tile inspection tile roofing diagnosis tile roof repair.