Roofing 101 – The more you know


You might be thinking, why do I need to know any of this? Isn’t Petrali Roofing supposed to be the expert?! While we certainly have a wealth of knowledge and experience gained from over 40 years in the roofing business, we believe the old saying that “knowledge is power”. Your roof is the largest, most expensive wear item on what will likely be one of the most significant investments you make. We want to equip you to make the most informed decisions possible when it comes to protecting your investment. Hopefully, you find this information helpful.


What Goes Into Your Roof?

All steep-slope roof systems (ex. roofs with slopes of 3/12 or greater) have five basic components:

Roof covering: shingles, tile, slate, metal, or wood (in some areas) and underlayment that protects the sheathing from weather.

Sheathing: boards or sheet material that are fastened to roof rafters to cover a house or building. Sheathing also gives your roof structure rigidity and strength.

Roof structure: rafters and trusses constructed to support the sheathing.

Flashing and drip edge: sheet metal or other material installed into a roof system’s various joints and valleys to help direct the flow of moisture down the roof to the drainage system.

Drainage: a roof system’s design features, such as shape, slope and layout that affect its ability to shed water.

Roof Coverings to Consider

There are a number of things to consider when selecting a new roof system. Of course, cost and durability head the list, but aesthetics and architectural style are important, too. The right roof system for your home or building is one that balances these four considerations and likely will lead you to one of following roofing products commonly used for steep-slope structures. It is not an all-inclusive list so if there are other materials you are interested in, feel free to ask.

Asphalt shingles possess an overwhelming share of the U.S. steep-slope roofing market and can be reinforced with organic or fiberglass materials. Although asphalt shingles reinforced with organic felts have been around much longer, fiberglass-reinforced products now dominate the market.

Tile (clay or concrete) is a durable roofing material. Mission and Spanish-style barrel tiles are used widely in the Southwest and Florida, and flat styles also are available to create French and English looks. Tile is available in a variety of colors and finishes. Tile is much heavier than shingles so if you are replacing another type of roof system with tile, you will need to verify that the structure can support the load. Tile is more expensive than shingles but it is also more resistant to wind and hail and is extremely fire retardant. Tiles roofs also have an insulating factor which helps keep your home cooler in the summer and warmer in the winter.

Metal roofs are also very common in our area, especially for those wanting the mountain home or cabin look. There are various kinds of metal roofs, from long panels that snap and screw together to stone coated steel that has the appearance of tile. Like tile, metal can also be expensive but it is very durable, fire retardant, and many metal roofing systems have been known to withstand winds of over 140 mph. Because we do tend to have a few snowy months, it’s important that your metal roof have snow stops installed to prevent large sheets of snow from sliding off and potentially injuring someone.

The Importance of Ventilation

One of the most critical factors in roof system durability is proper ventilation. Proper attic ventilation will help prevent structural damage caused by moisture, increase roofing material life, reduce energy consumption, and enhance the comfort level of the rooms below.

The general ventilation formula is based on the length and width of the attic and calls for a minimum of 1 square foot of free vent area for each 150 square feet of attic floor—with vents placed proportionately at the eaves (e.g., soffits) and at or near the ridge.

Things to Look Out For

A roof system’s performance is affected by numerous factors. Knowing about the following will help you make the best decision:

Sun: Heat and ultraviolet rays cause roofing materials to deteriorate over time. Deterioration can occur faster on the sides facing west or south. In Colorado we’re blessed with over 300 days of sunshine each year but that can take a toll on your roof over time. And, with as dry as it is here, some roof materials can become dry and brittle and eventually lead to cracking or breaking under other stressors.

Rain: When water gets underneath roofing materials, it can work its way to the roof deck and eventually could lead to rot with the roof structure. Extra moisture could lead to mildew and rot elsewhere in your house including walls, ceilings, insulation, and your electrical systems.

Wind: Colorado is not unfamiliar with wind. High winds can lift the edges of some roofing materials and once that structural integrity is compromised, there’s little to prevent water and debris from making their way underneath. Extremely high winds can cause extensive damage.

Snow and Ice: Melting snow often refreezes at a roof’s overhang where the surface is cooler forming an ice dam. This blocks proper drainage into the gutter and can allow water to back up under the shingles (or other roofing materials) and seeps into the interior. During the early melt stages, gutters and downspouts can be the first to fill with ice and be damaged beyond repair or even torn off a house or building. Depending on your elevation, you may be required to have ice and water shield installed to help prevent ice damming.

Trees and Leaves: Tree branches touching a roof will scratch and gouge roofing materials when the branches are blown by the wind. Falling branches from overhanging trees can damage, or even puncture shingles and other roofing materials. Leaves on a roof system’s surface retain moisture and cause rot, and leaves in the gutters block drainage.

Missing or Torn Roof Materials: The key to a roof system’s effectiveness is complete protection. When parts of your roof covering are missing or torn off, there’s nothing protecting the underlayment (the waterproof portion of your roof system) making your interior vulnerable to water damage and rot. Once part of the roof covering is compromised, the problem is likely to spread so be sure to have any mission roof covering repaired or replaced as soon as possible.

Shingle Deterioration: When shingles are old and worn out, they can curl, split, and lose their adhesion to the other shingles around them. Weakened shingles are easily blown off, torn, or lifted by wind gusts and the end result could lead to damage to the interior of the structure. A deteriorated roof system only gets worse with time and should be replaced as soon as possible.

Flashing Deterioration: Many apparent roof leaks stem from issues with flashing. Without good, tight flashings around chimneys, vents, skylights, wall, and roof junctions, water can enter a home or building and cause damage to walls, ceilings, insulation, and electrical systems.

If you’ve made it this far, we commend you! And now that you know this, we ask that you please NOT get up on your roof to check. Instead, use this information as a tool and ask questions of your roofer. You should be having your roof looked at least once per year but preferably twice and Petrali Roofing offers a free, 21-Point Roof Inspection. Should you ever have questions or concerns please feel free to call, text, or email. And for more content, stay tuned to this page as we work to provide other useful blogs, videos, as well as an archive of our previous blog topics.

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