Most Common Roof Pitch
A roof’s pitch is one of the most important considerations in roof design. Pitch isn’t just about aesthetics. It is important. But, roof pitch also affects how well water, ice, and snow drain. Pitch could also affect maintenance time and cost. Pitch can even change the materials you can use. In Colorado, what is the most common roof pitch for both commercial and residential properties?
What is Roof Pitch?
The pitch is the slope, slant, or angle of your roof.
It is usually expressed as a rise in inches for every horizontal foot of length. So a 6/12 roof would have a vertical rise of six inches per horizontal foot.
When architects are designing a roof’s pitch, they need to consider many things: the weight of the roofing materials, the projected lifespan of the roof, the cost, the maintenance required, and its appearance.
Most Common Roof Pitch for Residential Buildings
Conventional slope roofs are most common with residential roofs.
This means the slope has a pitch between 4/12 and 9/12 on most homes.
Roofs with a pitch exceeding 9/12 are called steep slope roofs.
Steep slope roofs are used for their beauty but they also have other benefits.
Most Common Roof Pitch for Commercial Buildings
Roofs on commercial buildings usually have a lower slope than the roofs of houses.
A typical low-slope roof has a pitch between 2/12 and 4/12.
A roof slope of under 2/12 is considered flat. Technically, it does have some slope.
To have drainage, the minimum slope must be at least ¼” per foot.
Designers of commercial buildings use low-slope roofs because they cost less.
Low-slope roofs can be used on large buildings like factories and warehouses.
Why Opt For a Steeper Slope?
Steeper sloped roofs are visually pleasing. They also last longer because water doesn’t accumulate.
Water, melting snow, and ice will run off immediately. This prevents ice damming.
Steeper sloped roofs are more expensive.
They require more materials and more labor. For some taller or larger structures, a steep slope just isn’t practical.
Relationship Between Materials and Pitch
Roof material selection is often dependent on the roof slope. Single-ply or torch-down roofs won’t work if the slope is steep.
If you want to use shingles or tiles on your roof, it can’t be a low-slope roof.
For roofs with a slope of 4/12 or above, shingles and tiles look and perform well.
Asphalt shingles are economical but they will have to be replaced sooner than other materials.
Tile is longer lasting.
Synthetic wood and slate roofing materials are both durable and longer-lasting. Many synthetic roofing materials look like natural materials and they are more durable and less maintenance intensive.
If you have a roof with a steep slope, roofing specialists will often recommend using shingles or tiles.
Clay tiles and natural slate have been around for centuries. The modern ones will last a lifetime if they are properly installed. They have two drawbacks: weight and cost. Clay tiles cost between $6 and $10 a square foot. Slate is twice the cost.
Concrete roof tiles cost about the same as clay tiles and the newer products mimic slate or clay tiles. They will last three decades.
Clay, slate, and concrete tiles weigh between 900 and 1,200 pounds per 100 square feet. If you are going to use this roofing material, the roof deck and supporting materials must be strong enough to support this weight.
Asphalt shingles are North America’s favorite roofing choice. They are versatile, coming in just about any color and style an architect or homeowner desires. Asphalt shingles work effectively on most residential roof pitches. They’re economical. They are fast and easy to install and relatively durable.
On roofs with moderate slopes, asphalt shingles will cost between 50 cents and $1.50 per square foot. Weighing about 250 pounds per 100 square feet, they are one of the lighter roofing materials.
The expected life of asphalt shingles—depending on the grade—is between twenty and fifty years. Climate and weather events like hurricanes, ice storms, or tornados can shorten this life span.
Another plus with asphalt shingles is that they can be used on low-slope roofs with a pitch between 2/12 and 4/12. However, it should be noted that they require special underlayment and installation techniques to handle such things as water and ice damming.
Metal roofing is commonly painted aluminum and steel.
Other options are copper and stainless steel. However, they are seldom used because of the cost. Aluminum is becoming a popular choice because it doesn’t rust.
Aluminum also isn’t as noisy when it rains. New aluminum roofing materials can also mimic cedar shakes, tiles, and slate—without the high cost, weight, and maintenance. Metal roofing materials will work on any roof pitch. Special seaming may be required on low-slope roofs.
Metal roofs are lightweight—between forty and a hundred and thirty-five pounds per 100 square feet. Metal roofs are also easy to install and long-lasting. For those looking for environmentally friendly roofing materials, metal is a good choice.
How Does Colorado Weather Affect Roof Pitch?
Colorado weather presents roofing challenges. Both altitude and various weather patterns require special consideration when you are choosing both roof pitch and roofing materials.
That’s why it is important to select a home or business structure designed for Colorado weather conditions.
It’s also wise to choose a roofing specialist familiar with the unique challenges of Colorado’s climate. You want roof pitch and roofing materials that will withstand the extreme Colorado climate.
Altitude affects your roof’s structure.
In higher altitudes of Colorado, things like air pressure, solar radiation, density, oxygen, temperature, and atmospheric water vapor change. The result is extra wear and tear on your roof. Routine roof maintenance will extend roof life. It is vital that regular gutter cleaning and roof inspection occur more often in higher altitudes.
In many climates, ice dams aren’t a concern. These lumps of ice form at the edge of a roof in winter. When this occurs, melting snow is blocked from draining. With nowhere to go, it backs up and drips into your home or business.
Roof pitch needs to be steep enough to allow water to drain so ice dams don’t occur.
Roofing insulation, pitch, slope, and ventilation all play a part in how snow accumulates, melts, and runs off the roof. Roofing specialists knowledgeable about Colorado snows can make excellent suggestions about how pitch and roofing materials impact roofing choices.
Those choices and installation affect whether a roof is insulated and ventilated. A roof with a higher pitch is usually more durable than a roof with a lower pitch.
Colorado is blessed with three hundred days of sunshine. This can wear on your roof. Warm days and freezing nights invite the formation of an ice dam. The blazing heat and UV radiation wear down many roofing materials.
To combat Colorado’s challenging weather conditions, select an optimum roof slope. Choose appropriate, well-installed roofing materials. Have regular roof maintenance and inspection by a roofing specialist knowledgeable about Colorado weather.
Common Roof Pitch Mistakes
Pitching a roof too steep or too low for the building and Colorado climate is a common mistake.
A minimum slope of four units of rise per twelve units of run is crucial if you are using asphalt, wood, or tile shingles or shakes.
Another is choosing roofing materials that don’t match the roof slope. This can result in water leaking into your home or business.
- Failing to take the winter climate into consideration can result in building water damage or even roof collapse.
Never assume that the slope that works on one home or business will work on all structures. The roof slope changes the materials which are appropriate for roofing. It even makes a difference when installing. Roofs with lower slopes allow for roll roofing with exposed nails. Roofs with higher pitches work best with shingles and tiles. The danger if you choose the wrong material for the slope of the roof is water penetration and costly structural damage.
How Can B & M Roofing Help?
Your roof protects your family or your business. It needs to be installed with materials that fit the roof slope. We are familiar with the most common roof pitch in Colorado and will recommend the best for your residential or commercial property.
For more information about the best materials and installation for your roof pitch or to inquire about a free estimate, contact us now.