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The Importance of Each Roof Layer

If you've ever seen a new roof installed on a home, you might notice multiple layers of material placed under the shingles. A roof isn't composed only of shingles or tiles but of numerous layers of different materials that all work together. Let's look at all the layers that go into a roof and their purpose.


Roof insulation is a barrier material laid between the rafters or the joists. Proper insulation slows down heat transfer between the outside world and your living space, creating a cooler home in summer and a warmer one in winter. In addition, insulating your attic space will help retain energy in your home, reducing heating and cooling loads on your HVAC, improving your home's energy efficiency rating, and lowering overall utility spending.


Your attic is part of your overall roof system and needs to be properly ventilated. The general purpose of roof ventilation is to encourage natural airflow through the attic space to keep it at a uniform temperature and humidity level. Ventilation systems typically consist of intake and exhaust vents installed in the roof or attic at strategic intervals.

Roof Deck or Sheathing

The roof deck is the layer installed over the framing and provides the base on which everything else is laid. The material used for decking varies, but most homes have plywoods. Ultimately the roof deck serves as a nail bed for the shingles.


Underlayment is a protective layer installed onto the roof deck. It offers an extra layer of water resistance against leakage caused by ice dams. The roof's underlayment prevents rain from getting under your shingles and prevents water from reaching the roof deck should the shingles be torn or broken.

Ice and Water Shield

A step up from traditional underlayment, this waterproof membrane is complete with an adhesive on the back. Its sticky surface allows the membrane to adhere to the roof deck and forms a watertight seal around nail holes.

Ridge Vents

These vents are installed at the peak of a sloped roof and are part of the roof ventilation system. This venting allows the hot air in the attic to rise naturally and be released to the outside. A properly installed ridge vent reduces demand for air conditioning and prolongs the life of your roof.

Roofing Material

The roofing material you choose is the final layer of the roof. The most common roofing materials for residential homes include shingle, shake, tile, metal, wood, or slate. Because they're almost always highly visible, roofing materials are important for building aesthetics in textures, patterns, and colors.


Roof flashing is a flat, thin waterproof material at the intersections of different planes of the roof. It is rolled out into place and then sealed to prevent water seepage at certain areas of your roof, such as chimneys, walls, vents, plumbing vents, valleys, eaves, and skylights.

Installation Matters

Improper roof installation can spell disaster for your roof, deadlines, and wallet. You want to choose a licensed, bonded, and insured contractor who won't cut corners when installing your new roof.

So when it's time to replace an older roof on your home, contact Ken-Z Roofing and be worry-free!

Ken-Z Roofing is family-owned and operated in Rockford and is just a phone call away. With 30+ years in the roofing industry in the Northern Illinois area, whatever your roofing needs, we are your local, professional roofing contractor you can TRUST. Call us today for your FREE 12-point roof inspection: 815-395-8244. Be worry-free with Ken-Z!

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