Low-Slope Roof What Are Your Options

Low-Slope Roof: What Are Your Options?

by

James
March 4, 2022
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If you want a low-slope roof installed on your home, you should know that it might not be steep enough for you to be able to put shingles on it.

This can seem limiting to you if you want to invest in a beautiful roof design for your home. 

Is a low-slope roof good?

While it might not be the norm, a low-slope or flat roof gives your home a modern appearance that can boost its appeal. 

There are many different roofing materials that you can install on a low-slope roof. Let’s check them out and also look at how flat and low-slope roofs compare to steeper ones. 

What Roof System Can You Install On A Low-Slope Roof? 

Low-Slope Roof What Are Your Options

Although you can’t install shingles on a low-slope roof, it doesn’t mean you can’t achieve a beautiful roof for your home. Here are some roofing systems that work particularly well.

Membrane Roof

Membrane roof systems are basically sheets of rolled synthetic that contain a water-repellent membrane. This is important because water doesn’t run off as quickly on flat roofs as it does on steeper roofs, so you want to protect your roof against moisture.

Types of membrane roof systems include EPDM, which is a rubber membrane, PVC, and TPO. Both PVC and TPO are reflective and available in white to make your home more energy efficient.  

  • TPO (thermoplastic polyolefin). This is a single roofing membrane that’s reflective and flexible enough to tolerate thermal contraction or expansion. 
  • PVC (polyvinyl chloride). This is flexible, maintains a cool temperature, and it can handle exposure to a large variety of chemicals. This is why it’s commonly used on kitchen roofs.

TPO Pros

  • TPO roofs are available in a variety of colors, such as white, gray, and black. Whatever color you choose, these roofs are designed to be UV-resistant.
  • These roofs prevent punctures, tears, and mold growth – all of these issues are non-existent with TPO roofs.
  • TPO comes in sheets that are lightweight, which makes installing this type of roof easy. 

TPO Cons 

  • TPO is still a relatively new roofing material, so it hasn’t been tested as much as other roofing materials.
  • It can only last for between 10 and 20 years, which is quite less than other roofing materials.

PVC Pros

  • PVC is strong and durable. 
  • It can last for over 20 years, so it’s value for money. 
  • PVC is resistant to toxic chemicals and it’s also fire-resistant. 

PVC Cons

  • PVC isn’t as suitable for cold climates, as it can become brittle. 
  • It can sometimes be difficult to repair. 
Low-Slope Roof What Are Your Options

Metal

A metal roof is a good choice for your low-slope roof. A standing seam metal roofing system is a particularly good option as it includes panels that get locked together at the seams.

This enables the panels to contract or expand freely depending on the temperature, while keeping them resistant to water. 

Pros

  • Metal roofs are lightweight, which makes them easy to install.
  • They are durable to cracks and tears, as well as harsh weather conditions. 
  • They can last for between 40 and 70 years, which gives them a much longer lifespan than many other roof materials.

Cons

  • Metal roofs come with a color-match consistency issue. If you have to repair them in future, you might battle to find the perfect color match. 
  • Metal roofs can be a bit noisy during heavy storms or hail. 

Built-Up Roof

This roof contains multiple layers of roofing felt that are treated with hot asphalt or coal-tar pitch (bitumen) to produce a watertight membrane. This membrane then gets treated with a coating or embedded with gravel.

Since built-up roofs have many layers of protection, if the top layer gets damaged your roof will still have other layers to prevent water from getting into the house.

Pros

  • This type of roofing can last for between 15 and 30 years. 
  • It’s an excellent roof in terms of being waterproof. 
  • It has good impact resistance, as it contains a layer of gravel on top that shields the home from hail, bird pecking, and falling tree branches.  

Cons

  • This roof doesn’t provide as much protection against strong winds as compared to other roofing materials. 
  • It can take a longer time to install, which can increase your installation costs. 

Steep-Slope Roof Vs Low-Slope Roof 

You might wonder if a steeper roof design is better than a low-slope or flat roof. Let’s explore the pros and cons of both of these roof types.

Steep-slope roof

Low-Slope Roof What Are Your Options

This is a common roof you’ll see on many homes. To be defined as a steep-slope roof, it needs a pitch of 18 degrees or more. Most commonly, this type of roof is covered in asphalt shingles, but you can install natural tile, composite tile, metal, or other roofing materials to it. 

Pros 

  • Rain water falls easier off a pitched roof than a flat roof. This dry quality of a steep roof prevents mold and mildew. 
  • Snow doesn’t accumulate easily on a steep roof. Since water and moisture can’t build up on a steep-slope roof too easily, snow is less likely to cause ice dams.
  • This roof ensures a larger attic space because it’s usually built on an A-frame design. 

Cons 

  • A steep slope can make it difficult for you to reach your roof, which can also increase labor costs for repairs and installation. 
  • It’s not practical or cost-effective for large facilities or commercial buildings. 

Low-slope roof 

Low Slope Roof What Are Your Options 1

By comparison, a low-slope roof has to have a pitch that’s below 18 degrees. Common materials used for low-slope roofs include PVC, TPO, EDM, and metal. 

Pros

  • This type of roof is simpler to install and therefore requires less building materials than a steep roof. 
  • A low-slope roof reduces how much air enters your home, which will help you to better regulate your indoor temperature. 
  • A low-slope roof gives you more space for additional installations. For example, it’s easier to add a sun deck to your flat roof than to a steep roof. 

Cons 

  • Snow and ice can easily accumulate on a low-slope roof. This could damage it.
  • A low-slope roof will experience more moisture and leaks, therefore it needs to be inspected and maintained more regularly. 

Why You Can’t Install Shingles On A Flat Roof 

Roof shingles are similar to fish scales in how they work. When they are layered on top of each other, they provide protection against external elements such as the sun’s UV rays or water.

For shingles to achieve this, they have to be installed on a roof that’s got a steep pitch of 4/12 or more. This produces a gentle incline that’s a midpoint between a low- and medium-pitch roof. 

Building codes provide the minimum roof-slope requirements for different roofing materials. As an example, a 1/4 :12 minimum roof slope is required for asphalt built-up, bitumen, thermoplastic single-ply, and liquid-applied membranes.

As for asphalt roofs, you need a 2:12 minimum roof slope for installation. Bear in mind that a low-slope roof can have a slope from 2:12 to 4:12. 

Low-Slope Roof Maintenance 

Low-Slope Roof What Are Your Options

If you have a low-slope roof, you will have to follow some important maintenance tips to keep it in good condition. Here are some good things to do and some things to avoid. 

Make sure you keep your roof clean

This is general roofing advice that you should follow for every type of roofing material you’ve installed. If your roof is flat or has a low slope, it will collect dirt and debris more easily than a steeper roof, which is why you have to regularly check it and remove debris with a roof rake.

Check the roof for leaks

While many roofing materials that are used for flat roofs are designed to be watertight and prevent leaks, such as rubber and PVC, you still need to regularly check your roof for any leaks.

A flatter roof is more prone to water accumulation, which can cause water damage to the roof and inside the home. Therefore, if you notice any leaks, you must repair them immediately, whether you do it yourself or you call a professional.

Inspect the roof for blisters 

This point is also linked to water damage. Blistering is when water becomes trapped between membrane layers of the roof, which causes vapor to expand when the temperature rises.

This pushes the membrane out so it bulges. If you don’t fix your blisters, these can cause problems to the structure of your flat or low -slope roof, so you have to repair them immediately. 

Remove snow from your roof 

Low-Slope Roof What Are Your Options

Snow should never accumulate on any kind of roof because it can lead to issues such as water damage. The weight of the snow can also be dangerous for the roof structure.

On a low-slope roof, snow won’t be able to slide off the roof as easily as on a steeper roof, so it will stick around for longer. It has to be removed, such as with a roof rake, because even if it does melt it can still cause problems.

The excess water won’t be able to flow off the roof. Make sure you remove snow when it’s about 12 inches thick to prevent such problems from happening. 

How Much Does A Low-Slope Roof Cost? 

When you’re thinking of installing a flat or low-slope roof, you’ll naturally wonder if it’s more or less expensive than a steeper roof pitch.

Generally, flat roofs are more cost-effective than steeper roofs. This is because you will require fewer materials to build them. Since you’ll need more roofing materials, such as shingles, when getting a steeper roof installed, this will not only mean you require more shingles but other materials too, such as roofing cement and nails. 

Low-slope roof installation can also be cheaper because a flat or low-slope roof doesn’t have angles and hard-to-reach areas that can make it more difficult to place shingles or other roofing materials on it.

However, the installation of flat roofs might require you to add an extra layer of insulation, which does come with extra costs. 

A low-slope or flat roof is known as a walkable roof. This is a term used in the construction industry to refer to how it can be walked on safely with the requirement for basic safety measures without anything additional, such as scaffolding. This is a bonus for roofing professionals – and it makes your job easier when you want to inspect or repair your roof! 

When it comes to working out how much you’ll have to pay for a low-slope versus a steep roof, let’s consider this example. If the roof is 40×50 feet in size, a flat roof could cost you about $6,000 to have installed, whereas a low-slope roof will cost about $7,000.

By comparison, a roof slope that has a slope of 5/12 could cost more than $7,200 to install. The prices keep increasing as the roof becomes steeper, so a low-slope roof will definitely keep your costs down.

Related Questions

How long can a flat roof last?

A flat roof can last for decades, but this does depend on the materials used to make it. 

How much underlayment is required for low-slope roofs? 

You should have felt underlayment that overlaps by a minimum of 19 inches on a low-slope roof. This will give the roof a double layer of underlayment to protect it. 

Conclusion 

If you own a low-slope roof, you have to ensure you look after it correctly to increase its lifespan. When it comes to installing a low-slope roof in your home, you have a variety of roofing materials from which to choose.

In this article, we’ve broken down your options, while also looking at the pros and cons of having a low-slope roof.

Sources:

James

James Weldon is a professional roofing contractor with many years of experience on the job. He does not only handle large projects and provide excellent services for his company’s many clients; James Weldon also dedicates his spare time to teaching others useful tricks of the trade. Using BuildCampus as an avenue to reach many roofers and aspiring roofing contractors, James Weldon continues to provide high-quality educational posts and buying recommendations for anyone who visits the website.