Your roof isn’t just made up of what you see.

A well-constructed roof is a system that works together to keep water out of your house. When you hire a contractor to redo your roof, they’ll have to tear off a couple of layers of material before they can put the new roof on.

The anatomy of a shingle roof

There are many different kinds of roofs, and they are all constructed a little bit differently with their advantages and disadvantages. It depends on the climate, the budget, the availability of materials, and more. The shingle roof is one that typically lasts the longest, and this is how it is constructed.

Shingles: Shingles are the outside layer of almost every residential roof, especially in this area of the country. They’re usually made of asphalt and an aggregate, and they are nailed overlapping each other like the scales of a fish or a snake. Shingles come in different weights, styles, and durabilities, but they’re all constructed similarly. The major difference is between the three-tab (the cheap one-layer shingles) and architectural shingles (multiple laminated layers).

Flashing and vent caps: Anywhere something has to go through the roof, you need metal to redirect the water. That’s where flashing and vent caps come in. Flashing is a flexible metal that’s used in areas like roof valleys and around chimneys. Vent caps cover exhausts and vents so water can’t get in.

Underlayment: This is the layer under the shingles. It’s sometimes called “felt” because older underlayment was tarpaper felt. Modern underlayment is a synthetic material that’s much stronger and resists punctures and leaks far better than traditional felt.

Decking: Decking is the wood that covers your house’s rafters or trusses. Shingles and underlayment are laid on top of the decking and nailed to it. This is usually plywood, though older houses may use solid 1×8 or 1×10 boards.