Uncovering Hidden Roof Layers: What’s Under the Shingles?

By Millstream Construction

Uncovering Hidden Roof Layers: What's Under the Shingles?

What lies below always tells a story, even when it comes to your roof. Typically, homeowners are unaware of the many hidden layers beneath their roofing shingles, the visible portion of the roof. Each sublayer contributes to the roofing system’s overall strength, appearance, health, and functionality. Together, they synchronize harmoniously to safeguard the home against external forces threatening a home’s well-being.

What Are The Residential Roof Layers To A Home?

Few homeowners understand the importance of the various layers that form a comprehensive roofing system. Each layer must be installed correctly in sequential order to ensure optimal performance.

Framing: Joists, Rafters, And Trusses

As the foundational layer of the roof, framing gives the roof shape (and, in most cases, slope or pitch). Joists align horizontally and distribute load volume to supports, beams, walls, and columns. Typically laid out as a triangular structure situated above joists, rafters (or, in the alternative, trusses) offer structural support for the combined weight of the roofing materials.

Grey Home With Dark ShuttersInsulation

Insulation serves a critical function in the health and vitality of the roofing system. Proper insulation retains energy and ensures that your home’s interior is cooler during the hot summer months and warmer during the cold winter months. In addition to this it:

  1. Minimizes heat loss escaping from your home. 
  2. Protects the remaining roof layers from extreme temperatures. 

Starter Strip Shingles

Also known as a shingle starter strip, this component (containing a specially positioned adhesive sealant) plays an essential role in decreasing the risk of shingles blowing off along the eaves and rakes. Incredibly, some roof installers do not incorporate starter strip shingles when constructing a new roof. Others improperly place them due to a lack of training and experience.

Roof Decking/Sheathing

Composed of thick sheets of plywood or OSB, roof decking attaches to the roof framing (by connecting the trusses/rafters and joints) to form a sturdy platform for additional layers. This essential layer ensures even (or balanced) weight distribution for the shingles and a means to stabilize other roofing components. Roof decking also serves as a nail bed for shingles.

Ice And Water Shield

This waterproof membrane protects the roof decking in the event that water (or other moisture) seeps under the home’s roofing materials. An ice and water shield is critical in ensuring moisture intrusion does not happen in or around roof valleys, penetrations, and edges. Typically, this shield is required in regions susceptible to snow and ice, helping reduce the effect of ice dams

Underlayment: Roof Membrane

Situated just under the outermost layer of shingles, the underlayment seals and reinforces the roof decking and adds a secondary water-resistant barrier (and works well against leakage caused by ice dams). Commonly made of fiberglass paper or felt, the underlayment produces a flatter, more uniform surface for shingle adherence. It also reduces the risk of shingles blowing off.

Cladding: Asphalt Shingles

Because of its availability and affordability, four out of five homeowners choose asphalt shingles (manufactured from a sturdy fiberglass base and coated with asphalt) as their roofing material. Naturally, other types of roofing exist, including wood, tile, metal, and slate. Cladding is the visible side of the roof and provides an aesthetic that incorporates texture, pattern, and color.


Ventilation is critical in clearing the attic space of excess heat and moisture. In effect, it protects the roofing system from damage. Heat and humidity can erode or rot framing and sheathing without sufficient ventilation. Mold and mildew also breed in locations of the home where heat or moisture is unmitigated. Adequate ventilation also reduces the risk of ice dams.

Hip And Ridge Cap

Hip and ridge flashing or shingles help maximize the overall performance and aesthetic of the roofing system. Installed across the top ridge of the roofline, this invaluable roofing component offers a weathertight and waterproof protective layer over the seam where the roof forms an apex. This component also safeguards the ridge vent, allowing air and moisture to escape from the attic.


Manufactured from sheet metal, flashing prevents water from penetrating seams and transition points on the roofing surface. Flashing surrounds vents, skylights, chimneys, and other roofing protrusions. Flashing along the roof eaves, called drip edge, helps keep water away from the fascia (and instead channels water to the gutters). Without a drip edge, water can seep under the shingles.

Choosing A Knowledgeable Roofing Contractor

Grey roof on White Home HomeNo roofing company provides higher quality craftsmanship and construction materials than Millstream Construction. If you own a home in Connecticut, Massachusetts, or Rhode Island, do yourself a favor the next time you have a roofing need. Make your first call to us. We will work with you to deliver the best roofing solutions in the industry. We won’t cut corners. We won’t oversell you. We will give you straightforward, honest service at a fair price.

To learn more about our roofing services or to schedule a free consultation, contact Millstream Construction today.

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