Low Slope Roofing 101: 10 Considerations to Keep in Mind

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Are you building a new home? What about renovating or repairing your existing structure?

If a new roof is in the plans, it’s critical to understand the exact type of roofing system you need. Specifically, the pitch of your roof is one detail to take into consideration.

In short, roof pitch measures the degree of slope on your roof. In most cases, it’s calculated as a ratio or an angular degree that describes how close one “exposure surface” on your roof is to being completely horizontal. You can choose from low slope roofing, steep slope roofing and a variety of scales in between.

Eyeing a low slope roof? If so, read on.

Today, we’re taking a closer look at the basics behind this type of roofing system. We’ll also share 10 tips that you need to know about low slope roofing, and how to best prepare for one.

Why Does Roof Pitch Matter?

You’ve got enough on your plate trying to choose the perfect shingle color and material. The options in that regard are nearly endless, so this decision can take time! In addition, you’ll also be tasked with choosing the shape, style and overall aesthetics of your roof.

Why, then, should you take the time to understand the pitch of your roof?

The short answer: This single measurement can affect a plethora of things about your end project. It plays a direct role in the roofing materials you can use, the way your roof will wear over time and the maintenance you’ll need to perform as a homeowner.

You see, roof pitch does affect the way your roof looks from the outside, but it goes much deeper than looks.

Depending on the type of pitch you choose, you’ll have your choice of roofing system and building materials that are best suited for the structure’s architectural needs. A professional roofing team can help guide you in this decision, helping you select a design that sheds water and debris as quickly and easily as possible.

What is a Low Slope Roof?

Technically, a low slope roof is commonly defined as any roof that rises no more than three inches per horizontal foot. While this pitch alone is minimal, there are even some roofs that are nearly flat.

In years past, low slope roofs were primarily reserved for commercial buildings. However, as minimalism and modernism have surged in terms of interior and exterior design, homeowners are more frequently requesting these designs for their residential properties.

It’s easy to see why: Low slope roofs are sleek, streamlined and decidedly contemporary. In addition, they also serve as excellent foundations for integrating solar and green roofing system solutions, which also increases their popularity in the United States.

However, for all of their benefits, they are not without their challenges.

In particular, low slope roofs have traditionally had issues with water evaporation and UV protection. In the past, roofers would seek to mitigate these issues by installing hot-mopped bitumen on the roof, as well as layers of cap sheets and gravel. However, newer and more tech-savvy techniques are revolutionizing this space and changing the methods used.

The key is to team with the right installers who can guarantee a job done right, the first time. Before you get too far into your project, take a look at these 10 considerations to keep in mind as you learn more about the pros and cons of low slope roofing.

1. Understand New Low Slope Roofing Materials

Today, you don’t have to settle for anything less than superior quality when installing a low slope roofing system.

As interest in this design spikes, roofers are employing newer and better solutions to help make sure yours will last for many years to come.

Single-ply roofing systems are one such innovative approach. While most are constructed of waterproof rubber, you can also find some that are manufactured with thermoplastic compounds, including TPO and PVC.

These single-ply roofing systems are Energy Star rated for maximum efficiency and are available in large rolls. They’re available in many different colors and are welded with hot air.

This last detail makes more of a difference than you might realize: It means roofers don’t have to contend with the odorous, hazardous tar kettles that most teams required for conventional hot-mop roofing!

Another perk? Most single-ply roofing systems are also compliant with cool roofing standards, and boast a Class A fire rating.

In your research, you might also find installers who utilize a modified bitumen, or torch roofing system, to build low slope roofs. This mid-range system doesn’t completely eliminate the hot mop process, but it does improve upon it.

With these systems, installers will integrate the bitumen into a specialized mat made of polyester and fiberglass. Then, they will roll out the mat and torch it directly to the deck of your roof. As with single-ply roofing systems, these are also available in many different colors.

2. Keep Your Pitch in Mind

Before you get too attached to a specific type of low slope roofing system, ask your contractor to explain the exact pitch of your roof. This is important because there are some roofing materials and pitches that simply won’t work with one another. In most cases, the magic ratio to keep in mind is 3:12.

What does this mean?

One of the most common ways to describe roof pitch is to calculate the number of inches raised compared to 12 inches run. In this regard, a “3 pitch” roof is the same as a “3 in 12 roof” or a “3:12 pitch roof”. This means that for every 12 inches of horizontal run, the roof rises three inches.

If the pitch of your roof is lower than 3:12, there are some materials that are not recommended for use. For instance, composition shingles or tile roofing systems won’t be a great fit here, as they cannot provide adequate drainage and protection. This can cause water to back up under the shingles or tile and pool, which can lead to significant damage.

Moreover, if you do use these materials on a slightly steeper roof (3:12 to 4/12 pitch), then they will usually require a double underlayment to ensure support. As an alternative, some contractors may use modified peel-and-stick protection solutions for these higher pitches in lieu of the double underlayment.

At Point Roofing, we use synthetic underlayment, as it provides superior protection and durability compared to traditional, organic-based felt or tar paper.

Over time, these earlier types of underlayment are prone to tearing or warping. They can also become brittle and even break apart. On the other hand, synthetic underlayment is designed to be sturdy and supportive, even as the years go by.

If you’re unsure whether a specific type of roofing material will work on your low slope roof, you can consult the International Residential Code (IRC). The IRC sets minimum requirements for roof coverings and explains which materials pair with which slopes. A few of the top ones to know include:

  • Asphalt shingles: Slope of 2:12 or greater
  • Clay or concrete roof tiles: Slope of 2.5:12 or greater
  • Metal roof shingles: Slope of 3:12 or greater
  • Slate shingles: Slope of 4:12 or greater
  • Wood shingles: Slope of 3:12 or greater
  • Wood shakes: Slope of 3:12 or greater

3. Consider Your Local Weather Conditions

When your roof is very low-pitched, some elements of your roofing system are working at the peak of their capacity. While this might be fine on a clear, sunny day, they can become too stressed in adverse weather conditions.

To even be available on the market, these products have to pass rigorous, extensive testing that ensures their quality and performance. This should give you some degree of comfort. However, unless an expert team installs your roof, it can be difficult to replicate those near-perfect testing conditions on your own.

Before moving forward with a low pitched roof, consider how much severe weather your region gets. If you’re used to experiencing a ton of snow, wind, or rain, then a steeper-pitched roof will be more accommodating of these factors. Either way, experience and skill matter in the roofers you hire.

Here in Idaho, our team knows that you’re no stranger to high winds. To that end, we only use nails to hold our roofing materials in place, following the industry-recognized best practice of storm nailing. This means we use six nails per shingle to offer the ultimate protection against the winds that pummel through this area.

Can the roofer you’re considering say the same? If not, consider this a red flag and continue your search elsewhere.

If an inexperienced roofing team takes the helm of your project, they could leave minor issues that snowball into major headaches. For instance, failing to eliminate all gaps in the tiling where it passes by the flashing could result in water ingress if it rains heavily. This is a costly and stressful issue that can be avoided.

4. Prepare to Wait

If you have a normally-steeped roof, an average amount of rainfall is not cause for major concern. In fact, you can likely look outside of your window during a storm to see the rain gushing off your roof and into your downspouts.

With a low sloped roof, this process isn’t quite as quick.

Due to the simple phenomenon of gravity, water just doesn’t trickle off these roofing systems as easily. Rather, you’ll find that they discharge rainwater and melted snow and sleet at a slower rate.

This is why it’s so important to choose the right roofing materials, along with a team that knows how to design your roof to ensure optimal drainage. If this standing water does not drain properly, it can gradually affect the wood structure underneath.

In turn, this can lead to rooftop ponding, drainage issues and more frequent leaks. Other issues that can exacerbate an already-compromised low slope roof include age, sunlight exposure, and temperature fluctuations.

While it’s natural to wait a little longer for water to drain from your low slope roof, it should still drain in an appropriate amount of time. You should contact your contractor immediately if you notice that water is standing on your roof with nowhere to go.

5. Ask About Rafters

Are you planning to install a low slope roof that also includes long rafters?

If so, your roofing team can help guide you on the best way to approach this step. With extra-long rafters, you could run the risk of water pooling on the surface of your roof. As this happens, it can trickle its way into even the most miniscule holes or gaps in your roof.

In effect, this could damage the underlay beneath and can even affect your battens over time.

For this reason, you’ll find that most roof tile manufacturers will set a maximum rafter length to help you avoid this issue down the road. If your rafters exceed these recommendations, it’s usually recommended that your roofers increase the pitch of your roof by one degree for every half-meter distance that the rafter goes over the limit.

6. Calculate Your Roof’s Headlap

In roofing, the term “headlap” refers to the process of overlapping the head of a roofing material by the material positioned two courses above it. This technique is most commonly used when installing slate roofing.

In general, the design helps all kinds of roofing systems stand up against wind-driven rain, which can catalyze the lateral movement of water below the shingles. Once there, it could infiltrate side joints and nail holes and weaken your overall roofing system.

In general, the lower that you decrease your slope, the more that you should increase your headlap. This way, when it rains, the water can run from your single-lapped or double-lapped tile onto the subsequent courses below. As long as there is sufficient lap and a large enough pitch, water should not creep sideways or upward.

Your roofing team can show you the recommended headlap required for the roofing materials you chose. These can be determined by carefully reading and following the manufacturer’s instructions.

7. Look at the Roof Above

Often, low sloped roofs are used on building extensions. For instance, you might use one to cover a back porch or patio area.

In this case, they’re often positioned below a roof that sits at a higher elevation.

When you’re planning your design, consider how much water could shed off that higher surface and impact your roof. There are certain building features that can affect this issue, including the presence of:

  • Downpipe shoes
  • Roof valleys
  • Dormer-side abutments

A downpipe shoe is especially challenging in this regard, as it can create a point load that dumps a ton of runoff water onto the low slope roof below. At the same time, valleys and abutments can also hold and harbor more concentrated loads of water, which can be equally damaging.

If your low slope roof is adjacent to a higher roof that has a greater degree of slope, your contractor can help design the system to minimize the amount of water that’s shared between the two surfaces.

8. Protect and Maintain Vulnerable Areas

Once you have the ideal material selected and the right low slope roofing design in place, it’s time to take a closer look at how you can best protect the most vulnerable and exposed areas of your roof.

With standard roofing construction, these aspects usually aren’t a substantial issue, but they can become major causes for concern on a roof with a slope that isn’t as steep.

Some of the areas of your roof that will be the most prone to water damage, leaks, and general wear and tear include the:

  • Eaves
  • Valleys
  • Abutments
  • Window surrounds

In any type of roof construction, these areas should be considered and protected. However, low slope systems render them even more exposed and as such, your contractor should take a closer look at the best ways to protect and safeguard them.

9. Ask About Warranties

Any time you begin a roofing project, it’s important to understand both workmanship and product warranties.

Our Point Roofing workmanship warranty spans the industry standard of 10 years. In addition, we are also well-versed on the warranties that all of our products carry and we’ll help you understand that information at any time.

Continuing our commitment to excellence, you can rest assured that we’ll never recommend anything less than a limited lifetime asphalt shingle. This is the most common residential roofing system available today, and one that we can assess for your low slope roofing project as required. In fact, all of the residential roofing products that our team installs are considered Limited Lifetime Products, and they usually boast a typical life expectancy of up to 50 years

In addition, we can also call upon our industry partnerships to bring you access to upgraded warranties as required. We are proud to be recognized as preferred contractors with both Owens Corning and IKO, which speaks to our expertise and good standing in this realm.

As low slope roofs can be more prone to certain issues, warranties like these are not simply nice to have. Rather, they are critical considerations that should be top of mind as you consider local contracting teams.

10. Seek an Experienced Local Contractor

Sure, there are some household projects that a family friend or work colleague might be able to help you tackle. For instance, you may decide to stain your back deck or install new kitchen faucets.

However, roofing is never a job that you should trust just anyone. This is especially the case if you’re considering a low slope roof.

Look for a reputable, qualified local team that has glowing reviews and a history of solid performance in your area. To get started, check professional contractor review websites, such as the Better Business Bureau (BBB).

At Point Roofing, our team exceeds customer expectations and industry requirements. Not only do we have an A+ rating on the BBB, but we’re also considered the area’s premier roofing experts for both commercial and residential work.

We’re committed to providing expert roofing solutions and will go out of our way to make sure your project is sound and successful. We’re happy to provide references upon request and we welcome you to check out our online gallery of “before” and “after” images that reveal our professionalism, quality and attention to detail.

In fact, we carry double the minimum insurance required by the State of Idaho, and our contractors always carry a copy of this certification so you can easily verify.

Your Local Resource for Low Slope Roofing and More

Are you local to the Boise area? If so, Point Roofing and Restoration is ready to become your trusted roofing expert.

If you’re considering any type of residential or commercial roofing projects, including low slope roofing, our team of qualified and experienced contractors can do the job. We also offer a range of roofing enhancements and upgrades, including solar tubes, ridge vents, custom gutters, water shields and more!

We’ve been the region’s leading roofing team for more than a decade, and we’d love to tell you more about our approach. Contact us today to learn about the services we provide and the difference we can make at your home or workplace. We can even provide a free inspection and quote upon request!