An entire roof system is held up by a roof deck (see assemblies). A roof system is all the roof components above a deck (i.e., a vapor retarder, insulation and roof membrane). Slanting a deck is one way to create slope. Remember, slope is important for water drainage.

A roof system sits on a deck. It is also attached to a deck. A roof system has to be secured to protect it from wind and other forces of nature, like rain and snowstorms.

Roof decks can be made of many different materials. Some of these materials include steel, wood and gypsum. Other materials are lightweight insulating concrete, concrete and cement-wood fiber.

If parts of a roof system (also called components) can be nailed or screwed to a deck, then a deck is referred to as nailable. Other decks are non-nailable. Roofing workers need to know the right way to secure roof components to a deck. the foreman will make sure that it is beinq done correctly.

Workers also need to make sure a deck is ready for a roof system to be installed. A deck has to be smooth, dry and clean.

Steel Roof Decks

The most common low-slope roof decks are steel roof decks. They are made of cold-rolled sheets. There are ribs in each panel that make them strong and rigid. The panels come in many thicknesses. There are also different sizes and spacings of ribs (see Figure 15).

Cement-Wood Fiber Roof Decks

Cement-wood fiber deck pan-els are made of wood fibers. First, they are bonded togeth-er with cement and other binders. Then, they are pressed together and molded into panels. These decks also provide some insulation.

Lightweight Insulating Concretes

On some roof decks, light-weight insulating concretes are used as fills or toppings. They are poured over another sur-face. They might be poured over something like corrugated metal or form boards. The con-cretes are made of lightweight insulating aggregates mixed with Portland cement and water. The insulating concrete is mixed, pumped in place and leveled at a job site.

Cellular concrete is another insulating concrete. This concrete has small air cells in it.

Gypsum Concrete Roof Decks

Gypsum concrete roof decks are made of gypsum material mixed with fillers. The mix-ture is called a slurry. It is poured over form boards that are supported by framing. The concrete mixture has steel wire mesh in it to make it stronger. This mixture can also be made into planks

Structural Concrete Roof Decks

There are two kinds of structural concrete roof decks. One kind is poured on site (poured-in-place). Another is made into planks (pre-cast) and then set in place.

Wood Roof Decks

There are many kinds of wood roof decks. One kind is a wood plank roof deck. This type is made of solid lumber. It is at least Y4 of an inch (1 9 mm) thick.

Another type is a plywood roof deck. It is composed of thin wood panels. It is usually about Y2of an inch (1 3 mm) thick.

And anothe r kind of roof deck is oriented strand board (OSB). Its panels are made of layers o wood strands. They are glued and pressed together. These are also at least about l@ of an inch (13 mm) thick.