Minimum Thickness Of Flat Roof

The definition of a flat roof according to bs 6229 is having a pitch less than 10 o to the horizontal however some in the industry would consider up to 15 o as their definition of a flat roof.

Minimum thickness of flat roof.

Never attach roof sheathing with staples. The idea is to provide positive drainage toward roof drains so there is no ponding water 48 hours after a rain storm. Tapered polyiso panels are manufactured in standard 4 by 4 sizes with a minimum thickness of at its low edge and maximum thickness of 4 for a single board. 2 the thickness or rating of roof sheathing on a roof not used as a walking deck shall conform to either table 9 23 15 7 a.

Flat roof drainage up until the early 1920s was still essentially to the outside the perimeter which required a minimal fall in one direction. Most flat roofs are typically not as long lasting or durable as sloped ones because the latter shed snow and rain a lot quicker. The ontario building code thickness or rating 9 23 15 7. Out of interest you mentioned furring pieces for slope.

The minimum slope for a flat roof is 1 4 per foot or 1 4 12 but some owners or insurance companies require a minimum slope of 1 2 per foot. That will suffice on a roof with rafters set 16 inches apart with minimal roof loads. 8d ring shank nails should be used instead. Minimum thickness most roofs will be sheathed in plywood at least 3 8 inch thick.

Others would treat even steeper pitches as flat roofs. Influential architects working in the early 1900s such as walter gropius and le corbusier saw ornamentation and traditional styles of architecture as. A flat polyiso underlayment board often referred to as flat fill is used beneath continuing repeating tapered panels. However over the last few decades new and advanced materials have been developed.

Sheathing should be a minimum of 19 32 inch thick. Minimum nominal thickness mm for application. Although there are certainly many times and places throughout the history of architecture where flat roofs have been used the flat roof has been intrinsically tied with modern architecture since it emerged from the modernist style in the 1920s. Tony thanks for that very useful.

A classic flat roof is either almost completely level or has a very slight pitch of 3 in 12 inches or less.