Is a Low-Slope Roof More Likely to Leak?

When you are having a roof installed or repaired, one of the biggest fears is probably having a leak occur soon after. Leaks in roofing can cause serious damage to not only the roof itself but the room and property the roof is covering. Issues like leaks can happen to any type of roof, but if you have a low-slope roof, you may be wondering if yours is more likely to experience this unfortunate situation.

Low-slope roofs have many benefits, but they also have a few potential risks. One of those risks is being more susceptible to leaking. Leaking can be more common in these types of roofs simply due to the way they are built.

Even though there’s a slightly higher risk than a roof with a greater slope, there are many things you can do to ensure that your low-slope roof remains leak-free, like working with the right professionals. People who work with experts like Interstate Roofing to have their roofs installed, repaired, and maintained can attest to the difference it makes when you have knowledgeable and skilled people to assist you.
Read on to learn more about low-slope roofs and how to keep them from experiencing leakage.

What Is a Low-Slope Roof?

After hearing that low-slope roofs may be more susceptible to leaking, you’re probably wondering if your roof is considered low-slope. Not many people know what kind of roof their house or property has, but knowing can help you to take preventative measures against leaks.
When you’re trying to figure out if you have a low-slope roof, you need to know what a roof pitch is. Roof pitch is the angle of your roof, and that angle relates to how much of a slope your roof has. Though it may be tempting to get on the roof and figure this measurement out yourself, you should avoid doing anything you don’t have the skills or equipment to do safely. A professional will be able to tell you what your roof pitch is and determine if it’s a low-slope roof.

A low-slope roof is one that is not steep enough to put shingles on and has below a 3:12 roof pitch. This ratio means that for every horizontal foot that the roof measures, it goes up no more than three inches vertically. If your professional roofing company tells you that your roof is measuring to this size or lower, then you’ll know you have a low-slope roof.

What Causes Leaks in Low-Slope Roofs?

There are a variety of reasons why leaks can occur more often in low-slope roofs. One of the most common causes is poor drainage. Unlike roofs with a high slope ratio, low-slope roofs are more prone to having water or snow sit on their surfaces. The lack of slope makes it easier for liquids to collect on the roof and can cause damage to an area. As the water pools in one spot, that spot of the roof becomes weaker and weaker, breaks down the roof’s compounds, and eventually finds its way into your home.

Another reason why low-slope roofs can be prone to leaking is due to a damaged membrane. When not taken care of properly and as a roof ages, it can form cracks and splits on its surfaces. These cracks are the perfect space for water to seep through to the insulation of the roof. As that liquid builds up in the insulation, leaking will begin to happen indoors.

How Can I Decrease My Risk?

One way to help decrease the risk of leaking for your low-slope roof is to schedule regular maintenance. Professional roofing companies often have maintenance programs available for customers so that their roofs can be thoroughly inspected on a semi-regular basis. At Interstate Roofing, the maintenance agreement program is designed to help customers prolong the life of their roofs through preventative maintenance.

For instance, if there is water pooling on your roof or damaged material, having preventative maintenance can help to catch that problem before any serious damage occurs. Without having those frequent checkups, home and building owners often don’t realize there is an issue until costly damage has been done and the roof is in need of large, expensive repairs.

Joining a maintenance program has other benefits too that can come in handy when it comes to leaking roofs. Many roofs and their materials have the option to be under warranty, which protects you in the case of an emergency. Though those warranties are useful, they often have requirements to remain active, and those requirements usually include maintaining some kind of regular maintenance or having an inspection of the roof completed. These types of programs protect your roof and your warranty, which may help you to avoid costly repairs down the road.

How to Find the Right Professionals

Because one of the reasons low-slope roof leaking occurs is due to poor installation, finding the right professionals to install, repair, and maintain your roof is important. Not everyone with a ladder and some tools is qualified to do work on your roof, so going through a thorough vetting process when searching for a roofing company is in your best interest.

When looking for a professional roofing company to work in your area, you should start by looking into how long they’ve been in business. Local businesses typically don’t last long in an area if they aren’t doing good work, so having a few decades of experience can speak greatly to the reputation and quality of a company.

Another thing you can look into is what type of credentials they have. A good roofing company will often have certificates, awards, and certifications that they readily boast about on their website. Lastly, you can rely on the reviews of others to help you make a decision. Ask your friends and neighbors who they use for their roofing needs and if they have been satisfied with their work. You can also check online for reviews from customers and testimonials on the business’s website.

Low Roof Pitch Options for Your Building

A roof has a “low pitch” if it slopes anywhere from 2/12 to 4/12 inches—meaning that for every foot the roof extends horizontally, the level of the roof rises two to four vertical inches. Some roofs have extremely low slopes and appear to be nearly flat. No roof, of course, should actually be completely flat. If it is, puddles of water will accumulate on the roof and ultimately damage it.

Low-slope roofs are seen on both commercial and residential buildings, although they are primarily associated with businesses. There is a reason for this: in commercial buildings, it is generally considered more prudent to maximize the use of space, leading to a flatter roof. Residential homes, on the other hand, tend to have a much steeper incline for cosmetic reasons.

Regardless of whether you’re looking for low roof pitch options for your home or your place of business, you’ll need to consider what materials are best. In this article, we’ll take a look at the choices available to you and other variables to consider when putting in a roof.

The Trouble with Low Roof Pitch

The primary advantage of a low roof pitch is maximizing space. It will allow you to utilize the space in your area all the way up to the top. This can create a number of advantages. Heating and cooling are easier in a building with a flatter roof, for example. However, low-slope roofs come with disadvantages that don’t trouble steeper roofs. The primary problem with a low slope has to do with drainage: water damages roofs, and water can begin to pool on a roof with too low of a slope. Ice and snow can also be a problem, depending on the climate. If water accumulates on your roof and can’t drain properly, it will eventually cause decay.

Direct sunlight can be another problem for a low-pitch roof, although this is certainly not an issue unique to these types of roofs. In fact, ultraviolet light can do a number on any type of roof, unless the proper materials are used.

This brings us to the primary disadvantage of a low slope roof: you are somewhat limited in the materials you can use to construct them. This is because of the importance of waterproofing. On a roof with a higher pitch, water will easily roll off, and that means you don’t need to concern yourself as much with waterproof materials. A low-pitch roof, on the other hand, absolutely must be waterproofed.


Low-pitch roofs are usually waterproofed through the use of a roof membrane, which can be made from synthetic rubber, a thermoplastic such as PVC, or modified bitumen. Any of these materials can effectively carry water off the roof without allowing it to pool anywhere or penetrate vulnerable areas and cause damage. Occasionally, asphalt roofing systems are also still in use, and while these types of roofs were extremely common in the past, they’ve largely been supplanted by synthetic membranes. This is because asphalt roofs don’t seal as effectively as other membranes do.

Types of Low-Pitch Roofs

There are several options when having a low-pitch roof installed for your building. These options, however, are more limited than those for a gable roof or other higher-pitch roof. Even so, there are several choices you can make as far as the construction of your roof, each with its own set of pros and cons.


Asphalt shingles are, as their name suggests, shingles made from asphalt and layered on your roof over felt, a synthetic underlayment, or thicker “ice and water shield”–type membrane. Shingles can be a controversial option for a low-slope roof. Most manufacturers allow shingles on slopes of 2/12 and greater, but most roofing contractors insist on greater slopes, as shingles aren’t “waterproof” but water shedding. Shingles are popular primarily because of their relatively low cost, ease of installation, and aesthetic benefits. However, installing shingles on a low-slope roof might be asking for problems. Consult a professional roofing contractor with many years of experience.

Single-Ply Membranes

Unlike with other roofing systems, where the material is built up over the membrane or layered on top of other materials, single-ply membranes are installed without the help of other layers. A thermoset or thermoplastic membrane is laid across the surface of the roof (generally over rigid insulation) and hot-air welded together. The most popular materials for single-ply membranes are PVC and TPO, which are usually reinforced with the addition of polyester or fiberglass. Single-ply membranes are a great, relatively inexpensive option that’s easy to install. However, because they’re only one layer, maintenance is critical.

Torch Down Roofing

This roofing system is made from sheets of modified bitumen—a hydrocarbon-based material—which is then sealed to the surface of the roof through the use of a handheld propane torch. The seams of the bitumen will melt and fuse together as a result of the welding process, creating seams that are completely waterproof.

This roofing material is great if you live in a particularly harsh climate. While other materials may expand or contract if the weather is hot or cold, modified bitumen will not. This material also has a long life span and is easy to repair, though it can be extremely difficult to install due to the use of the torch. As most of the roof decks in the Pacific Northwest are made of wood, the risk of fire should be a significant consideration. Only use a contractor with the CERTA certification.

Coated Roofs

For commercial buildings, one of the other popular low-pitch roof options is coated metal. Metal roofs aren’t waterproof in and of themselves, but they can be treated with a coating that makes them so. This coating helps reduce the instances of rust, increasing the life span of the roof. Generally, the coating that’s applied is a fluoropolymer paint, which allows the metal roof to become resistant to water and ultraviolet radiation. This option, of course, isn’t practical for commercial buildings that don’t have metal roofs.

If you’d like to discuss roofing options for your building, contact the professionals at Interstate Roofing. We’ve been serving Pacific Northwest for over 20 years and are always ready to share our expertise.