Technical Papers

Roofing anatomy 101

Tuesday, February 13th, 2018 by Suzie Elliott

ROOFING ANATOMY 101: Three Terms You Should Know

Minnesota homeowners in multiple cities such as Brooklyn Park, Blaine, Coon Rapids, Circle Pines, Champlin, Mound, Maple Plain, etc were severely impacted by the June 11, 2017, hailstorm. Many homeowners called NMC Exteriors immediately to schedule inspections, however many also opted to wait until Spring 2018 to deal with the damage and file an insurance claim. If you are a homeowner who is planning to schedule an inspection,  as well as file a claim to replace your roof in 2018,  a passing knowledge of some of the components of your roofing system will come in handy. Most homeowners are already familiar with the different roofing materials, but what about the other parts that make up a roof?

Here are three terms every layman should know, in order to better understand the anatomy of their roofing system: decking, underlayment, and flashing.  Let’s explore what they mean:

DECKING:  Decking refers to a roof’s “foundation.” Also known as sheathing, it’s made up of flat panels - usually plywood or oriented strand board (OSB) - that form the bottommost layer of the roof. The flat boards cover the roof rafters and are topped with a waterproof layer called the underlayment, which protects the decking from water penetration.

Because the decking is made of wood, it’s vulnerable to water damage. Constant exposure to moisture can cause the wood panels to delaminate, resulting in spongy, warped, or rotting areas. During the installation of a new roof, it is sometimes necessary to repair or replace the sheathing, depending on the extent of the damage. It’s pointless to install new shingles on a compromised roof deck.

UNDERLAYMENT:   As we mentioned above, the underlayment is the waterproof layer that protects the decking from excessive exposure to moisture. It is sandwiched between the wood decking and the primary roofing material, such as asphalt shingles or metal panels. The most common underlayment material used in roofing today is a synthetic felt membrane.

This protective membrane plays a key role in extending the life of your roof. By keeping water out, it saves the decking from rot and preserves the structural integrity of your roof.

FLASHING:   Flashing is another roof component that protects your roof from water damage. Flashing is metal strips that cover up joints and penetrations in your roof, such as dormers, hips, and valleys and the areas around chimneys and vents. These spots tend to be vulnerable to leaks, which is why it’s important to add flashing around them.

Flashing is applied over the roof surface, which means it’s exposed to the elements and may get damaged over time. To ensure your roof stays protected from damage caused by water leaks, faulty flashing should be repaired or replaced immediately.

These are only some of the parts of your roof that may come up during your free consultation with an NMC Exteriors & Remodeling project manager. Please don’t hesitate to ask our project managers for clarifications whenever necessary.

As one of the leading roofing contractors in and around the Minneapolis-St. Paul area, NMC Exteriors & Remodeling understands the value of educating homeowners about their roofing systems. This is because we know that you yourselves are our most valuable partners in roof care

For more information or to schedule a free, no-obligation inspection of your roof for this spring, call NMC Exteriors & Remodeling at 763-260-8537 or email our Office Manager at [email protected]


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