Ratios from that minimum up to 4 12 which are considered low pitch require double underlayment.
Minimum slope for clay tile roof.
Clay and concrete tile minimum roof slope roof pitch r905 3 2.
The following table provides the minimum required allowable roof slope for each type of roofing material mentioned in the code.
Anything lower than this angle is rare and although there are specific products that can go lower 15 is the most common minimum angle for clay tiles.
This means for every 12 horizontal units the roof must rise a minimum of two and one half vertical units.
This article series explains clay tile roofing types clay roofing tile inspection tile roofing diagnosis tile roof repair.
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.
The minimum roof slope allowed by code for any type of roof is in 12 applicable only to coal tar pitch roof systems.
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.
The short simple answer is 2 12 has traditionally been considered the absolute minimum acceptable roof slope suitable for asphalt shingles.
Tile covered roof installation specifications.
This minimum pitch is important if tiles are laid below the recommended minimum pitch there is an increased chance of water getting through which can damage the underlay and battens over a prolonged period.
Likewise the nails used to attach clay tiles to the decking should be corrosion resistant copper or stainless steel.
Clay tiles are colorfast which means their tints improve rather than fade over time.
Aluminum or galvanized sheet metal sufficient for the life of an average asphalt roof would be the weakest link in a clay tile roof.
Asphalt shingles continue to be the most widely installed roof covering option in north america.
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.
Instead flashing for clay tile must be formed from heavy gauge copper or stainless steel.
The irc recommends a minimum pitch of 2 5 12 for these materials.
Clay and concrete roof tiles can only be installed on roof slopes of 2 1 2 12 or greater.
For many years 20 was recommended as the minimum pitch for clay tiles but this has decreased in the modern era down to 15.
They provide excellent weather resistance great value and now more than ever a tremendous range of beautiful designs and color blends.
Concrete is long lasting with a minimum lifespan of 50 years depending on climate.
