Minimum Flat Roof Thickness

Never attach roof sheathing with staples.

Minimum flat roof thickness.

Roof sheathing comes in grid marked 4 by 8 foot sheets and should be installed perpendicular to the frame. There are two types of flat roof. 1 2mm standard 1 5mm commercial resitrix. As the single ply roofing association spra points out this type of flat roofing is strong durable completely sealed and usually lasts at least 25 30 years.

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. Each gauge represents a nominal decimal range. Minimum thickness most roofs will be sheathed in plywood at least 3 8 inch thick. 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.

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. As opposed to old built up felt roofing with joins new single ply waterproof membranes are now most commonly used. The problem with metal roofing gauge is that there is a wide range of tolerances. Sheathing should be a minimum of 19 32 inch thick.

The typical thickness range for sheathing is 3 8 to 3 4 inch. Flat roofs come in many shapes and sizes which include parapet roofs roof decks and green roofs to name just a few of the options available. The thicknesses are listed below. Ultimately a flat roof should play a part in a total architectural composition and has the ability to enhance the aesthetic and practical outcomes of a home.

We sell a total of five roofings systems. Manufacturers express the thickness of metal panels as their gauge with 22 gauge being the thickest and 29 gauge the thinnest of traditionally sold metal roof and wall panels. That will suffice on a roof with rafters set 16 inches apart with minimal roof loads. Four are epdm membranes and the fifth is a polyurathane liquid.

For example one company might sell a product as being 24 gauge but in reality the thickness of the metal could vary from 0 018 to 0 0335 based upon exactly how that company looks at things and how big of a tolerance they allow for. You can read our article about calculating slope for information on the various roof slope notations.