Nowadays, there is an abundant variety of materials you can choose to install on a your new-construction roof or retrofit project.
Residential roofing materials can vary in their visual appearance/curb appeal, weight, material cost, durability and longevity, and roof maintenance requirements.
Major Factors Influencing your Choice of Suitable Materials:
Your roof’s steepness, also known as a roof pitch, or a slope of your roof, can impose roof-slope-specific limitations on your choice of suitable roofing materials for your particular type of roof.
What is the Difference between a Gentle and a Steep Roof Slopes?
The more level a slope of your roof, the slower a runoff of the rainwater will be….
Implications of a Low Slope Roof: Naturally, the rate of a rainwater runoff from any roof with a relatively low slope will be slower than that of a steeper roof. Hence a slow runoff calls for an especially waterproof roof covering. A flat roof surface can be covered with specialty low-slope roofing membranes such as PVC, TPO, EPDM rubber, modified bitumen, built up roof (BUR), or a specialty “Cool” flat roofing membrane like the one manufactured by IB Roofs.
Due to a necessity calling for special skills, tools and precision instruments required for a proper installation of IB flat roofing system, or some other specialty membrane, it is imperative that such a system is only installed by properly trained specialists/professional roofing contractors.
Should I Repair or Replace My Low Slope/Flat Roof?
Depending on the age and overall condition of your current flat roof, there is a chance that it may be repaired by a knowledgeable specialist, if an appropriate repair is started early enough…
A roof of a gentle slope, can in theory be covered with conventional rolled asphalt roofing, but despite benefiting from its inexpensive cost, you can only expect rolled asphalt roof to last 5-7 years before it fails.
Therefore, if you want to avoid having to replace your roof in some five short years, or even earlier, it makes a good financial sense to invest in a more durable roofing system such as a flat roofing system manufactured by IB roofs.
If your roof rises four inches, or more per one foot of its base, then it is considered a steep roof, which means that your roof is suited for a wider range of roofing materials such as asphalt shingles, slate, clay tiles, wood shingles and shakes, and a wide range of metal roofing systems.
Estimating and Ordering:
Most roofing materials are sold in units called roofing squares. Each roofing square is equal to 100 square feet of roof surface. (The only exception is rolled roofing, and flat roofing membranes that come in rolls of varying lengths, widths and weights). In order to estimate roofing materials needed for your roof, first determine the total area of your roof’s surface, add 10 percent to allow for double layers of roofing materials along ridges, eaves, and hips, and round up the total to a next roof square (next 100 square feet).
Asphalt Shingles – Inexpensive – lasts – 15 to 20 years – Minimum Roof Slope required 4 in 12. Asphalt shingle roofing is easy to install. It is available in wide variety of weights, colors, and styles such as 3-tab and architectural shingles. Other than occasional cleaning and roof moss removal, asphalt shingles require little maintenance and are easy to repair. Darker colored asphalt shingles may not last as long as lighter colored shingles due to higher impact from the sun exposure. Asphalt shingles are not easy to recycle, which is why it often ends up in our landfills at the end of its service life.
Rolled asphalt roofing – Inexpensive – lasts – 5 to 7 years – Minimum Roof Slope 1 in 12. Rolled asphalt roofing is easy to install and repair. Limitations: Poor fire resistance for some types, gets very hot in the summer, and transfers a lot of thermal heat from the sub inside the building, requires frequent replacements.
Built-up or Modified Bitumen – Moderate in price – lasts 10-20 years – minimum slope 1/4 in 12. Modified Bitumen is more waterproof than rolled roofing, but it has a poor fire resistance for some types; must be installed professionally; leaks are difficult to locate.
EPDM Rubber – Moderate in price – lasts 15-20 years – minimum slope 1/4 in 12. Must be installed professionally. Leaks usually occur in the seams; can be easily repaired if leaks are identified.
IB Roof (Modern PVC cool flat roofing membrane) – Lasts 30-50 years – No minimum roof slope requirement – can withstand ponding/standing water and ice, can further be outfitted with PV solar roofing panels. Considered as a CoolRoof, and accredited by the US Green Building Council, IB flat roofing membrane reflects most of a solar radiant heat, which helps keep a building protected by the IB roof much cooler than a similar building with an ordinary roof would be.
This reduces your energy expenditures during the season of high temperatures. A PVC roofing membrane like IB roof can be properly recycled at the end of its rather long service life.
Wood Shingles and Cedar Shakes – Moderate to expensive in cost (Comparable to the cost of metal roofing) – Lasts 15 to 30 years – Minimum roof slope required: 3 in 12 for shingles, and 4 in 12 for cedar shakes. Offers attractive rustic appearance, and acts as a natural insulator. Limitations: Highly flammable unless specially treated; shingles must be laid over open planks, or spaced battens.
Slate – Expensive – lasts 50 to 100 years – minimum roof slope required: 4 in 12. Offers a highly attractive and traditional appearance, fire resistant. Limitations: Heavy; brittle; requires sturdy roof support; tricky installation that requires special tools; needs regular replacement of damaged pieces; difficult and expensive to repair.
Roof Tiles – Moderate (concrete) to expensive (clay) – lasts 50 to 100 years – minimum slope 4-12. Offers attractive and unique appearance; fire resistant. Heavy; brittle; requires sturdy roof support; time consuming installation; availability of replacement pieces unreliable; difficult to repair.
Metal Roofing – moderate on higher side for galvanized steel and aluminum shingles; expensive for copper lasts 30 – 100 years depending on the system; fire resistant; Offers beautiful modern appearance and a great variety of styles, and finishes. Metal shingles roofing system features a 4 way interlocking design, which provides reliable wind uplift protection, as each shingle is interlocked with metal shingles next to it. Roof you see below is made with G-90 steel coated with Kynar 500 cool roof rated solar reflective coating. This particular roof was installed in Rhode Island.
Below you can see a standing seam roof, made from aluminum sheet metal roofing panels. This this roof was installed near Boston, Massachusetts. You can also see that standing seam roof has a rail snow guard system, to stop the snow from sliding down the roof. High-end standing seam metal roofing panels are coated with special coating that helps shed snow and ice, which is especially useful in northern Massachusetts, and New Hampshire where there is significant accumulation of snow. Standing seam roof can last a lift time of the building and help prevent ice dams on your roof.
While standing seam is a premium roof that comes with a price tag, there is a less expensive alternative that has been in use for many years on agricultural and industrial buildings, barns and farm houses. Corrugated metal roofing is usually made out of thin gauge steel in comes in U shaped form. Although, it was primarily an agricultural type of roofing material, modern day corrugated metal roofing can be used to roof over a residential house. For instance, a galvalume steel or aluminum v 5 crimp panel coated with Kynar paint finish could be used in residential roofing.
Corrugated Metal Roof on a Residence
Comparing Roofing Materials
In this post, a term “Cost” refers to a relative cost of roofing materials alone, and does not include the cost of labor. In most cases, the cost of professional installation is higher for roofing materials like natural slate, clay tiles, wood shingles, cedar shakes, and metal roofing than it is for regular asphalt shingles, or rolled asphalt roofing.
A minimum required roof slope is a roof pitch at which a specific material begins to provide adequate protection against rain water. All the materials listed can be applied to roofing surfaces steeper than a minimum roof pitch indicated, but as roof slopes increase, considerations such as appearance, durability and longevity become far more important.
“Durability” provides a rough measure of a length of time a roof will last with proper maintenance in a temperate climate.