Roof Structure Thickness

As a general rule roofs that have a high human occupancy rate should be framed with rafters every 16 structures such as sheds or barns can be frames with rafters every 24 again make sure to consult local codes.

Roof structure thickness.

Roof sheathing comes in grid marked 4 by 8 foot sheets and should be installed perpendicular to the frame. The typical thickness range for sheathing is 3 8 to 3 4 inch. The roof s structure the sheating and the shingles all add to the thickness. The problem with metal roofing gauge is that there is a wide range of tolerances.

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. This is especially true of intensive green roofs which can have soil that is two feet deep or more. It is common practice to use the term extensive to describe green roofs that are very thin and will only support hardy drought resistant vegetation such as sedums herbs and perennials. It is also important to factor in the type and lifetime of the roof membrane that will be used.

The nominal thickness of a green roof is the approximate total height of the soil and drainage components that constitute the green roof system excluding the roof structure insulation waterproofing and plants. Comstock comstock getty images the roof of the house must be structurally sound to support the weight of the shingles. 07 41 13 structural 07 61 14 00 20 steel standing seam roofing 07 61 15 00 20 aluminum standing seam roofing 07 41 13 16 copper roof system flashing and sheet metal. Green roofs tend to improve the life of the membrane because it is completely covered by plantings and isn t exposed to the sun s harsh uv rays.

Unlike with plywood siding the plywood sheet to be used for sheathing should be at least 3 8 inch thick. If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center. That s considered to be the minimum. Intensive to describe green roofs that are thick enough.

Sheathing should be a minimum of 19 32 inch thick.