When something goes wrong with your home’s roofing system, your first thought is likely, “How much is this going to cost me?” Repair work for roof damage is notoriously expensive, and you typically have no choice but to trust the roofing contractors when they tell you the problem and the cost of fixing it.


If you’re a homeowner, it can be a huge advantage to know more than the average person when it comes to roof anatomy. Instead of absently nodding along with whatever the contractor says, you can make informed decisions based on the knowledge you’ll gain from this article.


Let our team at Johnson Exteriors, LLC, of Minneapolis, MN, talk you through from the inside out and help you learn about each element of a typical roofing system.


Roofing Structure

Your roofing structure has rafters, trusses, or beams that form the shape of the roofing system. The frame also determines the slope of the roof, which affects how water from rain or melting snow runs off. Residential homes typically have roofing structures made of wood, and commercial buildings have steel frames.


Roofing Deck

Also known as sheathing, the deck is the structural foundation of the entire roofing system. During construction, the roofers secure flat pieces of material to the frame, creating a bottom layer that will support the weight of the rest of the roofing system and extra force from snow, ice, or debris.


The deck material is typically plywood or oriented strand board (OSB). The boards’ thickness depends on:

  • The roof’s slope
  • Spacing between the rafters
  • The weight of materials on top
  • Weather risks like heavy snow

Since the decking supports the weight of your entire roof and its structures, it’s crucial to prevent water damage to the material.



Underlayment is a layer of waterproof or water-resistant material beneath the roof’s covering that protects your roof’s decking. The three primary types of underlayment include:

  • Rubberized asphalt (waterproof)
  • Asphalt-saturated felt (water-resistant)
  • Synthetic underlayment (water-resistant)

Waterproof underlayment like rubberized asphalt is impenetrable to water, while water-resistant materials block most of the water but aren’t leak-proof.

Fire-rated underlayment helps prevent flames from spreading through your home and is most common for homes in fire-prone regions. The type of underlayment your home needs mainly depends on your climate.



Your roof has tiny gaps, such as eaves and valleys, that jeopardize the decking underneath by creating a path for water to get in. To prevent this from happening, roofers add flashing to these gaps. Flashing is typically a corrosion-resistant strip of metal attached to the edges of chimneys or walls that keep water away from exposed roofing.

Roofers use a combination of different types of flashing, such as:


  • Step flashing
  • Cap flashing
  • Valley flashing
  • Drip edge

You can use various metals for flashing, including steel, aluminum, copper, or stainless steel. Leaks commonly happen when you have damaged flashing, so it’s likely the first thing roofers will check when you call about water getting into your home.



Not many homeowners realize how important ventilation is in their roofing system. Ventilation creates airflow between the outside and inside of your home, specifically your attic. It allows warm, moist air to escape your home (exhaust) while letting cool air in (intake).

A proper ventilation system can provide you with the following benefits:

  • Regulating temperatures in your home
  • Reducing energy costs
  • Increasing the life span of your roof
  • Preventing ice damming

Ice damming happens when snow piles up on your roof and melts because of the warm air rising into your attic. The runoff flows into your gutters, where it starts to freeze again. Ice builds up, blocking the gutters and forming icicles that hang over the roof’s edge. All that ice can lead to damage that lets water into your roofing system and home.



The covering is the outermost layer that carries the aesthetics of your roof and acts as the first line of defense. Asphalt shingles are the most common covering material for American homes because they’re affordable, relatively sturdy, long-lasting, and come in various styles.

Additional roof covering materials include the following:

  • Tiles (clay, concrete, etc.)
  • Slate
  • Metal
  • Rubber
  • Wood shingles


Asphalt Shingles

Asphalt shingles are one of the cheapest roofing materials and offer adequate protection for many types of homes. The shingles come in different colors, shapes, and styles to complement the look of your house, whether it’s contemporary or traditional. They can last between 20 to 30 years and withstand typical weather hazards like wind, snow, and ice.



The most common material for tiles is clay, and you’ll often see them on homes with terracotta roofs. Terracotta is mostly seen on seaside homes in sunny climates since the material is suitable for hot, salty air.



Slate shingles are genuine stone and very heavy, requiring a solid roofing foundation to support them. They’re more expensive than other roofing materials, but their durability and beautiful appearance make up for the extra cost. 



Metal roofing is long-lasting, durable, and resistant to extreme weather. Typically made of copper, aluminum, or steel, metal roof tiles will stay intact much longer than your typical asphalt or wood shingles.



Rubber is a relatively lightweight, durable, and affordable synthetic roofing material. The looks of rubber can adapt to whatever color, style, or texture you want on your home.


Wood Shingles

Wood shingles and shakes add a rustic, traditional look to your house. The wood is typically cedar but can also be pine or redwood. A wood roof covering might be unsuitable for homes in wet or fire-prone areas.


Skilled Roof Repair and Replacement in Minneapolis, MN

Did a storm wreak havoc on your home’s exterior or roofing system? Call us at Johnson Exteriors, LLC, today at 763-355-4458.

We have decades of experience navigating claims processes and repairing roofs for residents in the Minneapolis area. Our fully certified and insured team is ready to take on any roofing projects, whether you need minor repairs or a total roof replacement.

Our dedication to every client’s satisfaction sets us apart from other contractors and delivers a positive experience during a frustrating time.