more layers than a cake

One of the best parts of building a house is learning the process behind everything. I knew a little about the layers of a roof but watching each of them go on made me realize there was more to learn. Below is a high level overview of the various layers to a shingle roof:


Framing – this includes the roof trusses that sit on top of your house and support the materials to build your roof. Depending on the weight of your roofing materials, the trusses may be designed differently.

Insulation – this sits inside your attic and walls and helps your house to be more energy efficient. Insulation is common on the attic floor and between the rafters but can be varied depending on your preference. The various types of insulation also have different ratings based on how energy efficient they are and how well they work. 

Ventilation – every attic needs to breathe whether it is on an old house or a new house. It is critical that the attic can get rid of the heat and moisture that if left, can damage your trusses and other roofing material. When selecting insulation, this is something important to keep in mind.

Roof decking – this is the material that sits on top of the roof trusses and is generally made out of some type of plywood-like material. The different sheets of plywood are nailed into the trusses and attached to one another to form a solid base roof layer.

Water shield – this layer creates a water-proof barrier to keep the decking dry. Many common brands are a peel and stick. 

Underlayment – this is normally a felt or fiberglass paper and covers the entire roof decking. It is water resistant but will also moisture in steam form to pass through while preventing water in liquid form from passing.

Roofing Material – in our case, this was shingles which are laid from the bottom of the roof line or closest to the edge of the roof to the top of the roof line. This allows the water to flow without getting caught up under the shingles.

Ridge Vents – these vents are at the top of the roof line and allow for ventilation in the attic.

Flashing/ Drip Edge – generally a type of sheet metal cut in strips and is used to cover the intersection or joints of different materials. It is common to see it around skylights, bathroom vents, along chimney lines, roof eaves or any other feature that sticks out from a roof line.


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