Minimum Flat Roof Thickness

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.

Minimum flat roof thickness.

As opposed to old built up felt roofing with joins new single ply waterproof membranes are now most commonly used. Roof sheathing comes in grid marked 4 by 8 foot sheets and should be installed perpendicular to the frame. 1 2mm standard 1 5mm commercial resitrix. Each gauge represents a nominal decimal range.

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. Loads will vary with the. There are two types of flat roof. Cold roofs and warm roofs.

Sheathing should be a minimum of 19 32 inch thick. Four are epdm membranes and the fifth is a polyurathane liquid. 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. Never attach roof sheathing with staples.

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. Minimum thickness most roofs will be sheathed in plywood at least 3 8 inch thick. We sell a total of five roofings systems. 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.

The problem with metal roofing gauge is that there is a wide range of tolerances. The typical thickness range for sheathing is 3 8 to 3 4 inch. 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. You can read our article about calculating slope for information on the various roof slope notations.

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. The thicknesses are listed below.