Flat Roofs Versus Pitched Roofs: Which Will Work Best for You?

Posted on by Dr Roof Inc
Roofing Vancouver WA

Flat Roof or Pitched Roof

One of the most important decisions to make when buying or designing a new home is what sort of roof will work best for the homeowner. Generally speaking, homeowners must decide between flat or pitched roofs. While the aesthetic of the home is essential, of course, homeowners should contact qualified roofing contractors to determine the best type of roof for the home in question. That said, concrete advantages and disadvantages come with both flat and pitched roofs.

Measuring a Roof’s Slope

It’s important to realize that flat roofs are not truly flat. All roofs must have some slope to drain after it rains. A more accurate way to describe “flat” roofs is low-slope roofs. Roof pitches are measured by their fall over twelve inches. For example, if a roof falls two inches vertically over a horizontal width of twelve inches, it’s called a 2 and 12. Flat roofs are usually 3 and 12 or less, while pitched roofs are 4 and 12 or more.

Flat Roofs

Membrane Systems

Flat roofs require membrane systems. Because of the low slope of the roof, flat roofs are at risk of leaking after rainfall or other precipitation. A membrane system is a roof covering installed on top of the roof that allows for standing water to drain. Torch-down, single-ply, and built-up membrane systems are the most common types of membranes installed on flat and low-slope roofs. Roofs with pitches below 3 and 12 cannot have shingles; low slope roofs with pitches at 3 and 12 must have shingles installed in a specific way to prevent leaks.

The Disadvantages of Flat Roofs

Flat roofs are generally regarded as troublesome. But, like any roofing system, the quality of a flat roof depends on the quality of its installation. Disadvantages to flat or low slope roofs include difficulty locating leaks, increased likelihood of leaks, shorter useful service life, and a more expensive installation cost. However, new single-ply membrane systems come with 50-year warranties. While it’s unclear if these membrane systems last half a century, they are undoubtedly superior to older membrane systems which often only last 15 to 20 years.

The Advantages of Flat Roofs

While flat roofs can cost more than pitched roofs and often require more maintenance, lower-sloped roofs have a clear advantage to homeowners. Flat roofs have large overhangs that do not block light because of their low slope. Natural light has plenty of physical and mental benefits, and lower-sloped roofs make natural light a bit easier to obtain inside of the home. Additionally, the overhangs protect the exterior of the house. While a flat roof may result in higher roof maintenance costs, it will save homeowners money concerning siding, window, door, and deck maintenance. Also, flat roofs are considered to be one of the most energy-efficient roofing options available for homeowners.

Pitched Roofs

Roofers Vancouver Wa

The Disadvantages of Pitched Roofs

Pitched roofs have slopes that typically measure at 4 and 12 or more. If the home has more than one pitched roof, referred to as complex rooflines, this can result in higher costs related to maintenance. Complex rooflines often contain other things, like HVAC systems, ductworks, skylights, and vents. Simplicity is vital when it comes to considering future roof maintenance costs. Another downside to pitched roofs is that the overhangs may block light from entering the home. Additionally, pitched roofs can result in higher costs in areas with high winds.

The Advantages of Pitched Roofs

Pitched roofs have plenty of advantages. First, they are usually less expensive to install than flat roofs. While the surface area of a flat roof is smaller than that of a pitched roof, shingles are much cheaper than membrane systems. Shingles are also much easier to install than membrane systems which reduces the installation cost. Another advantage of pitched roofs is lower maintenance costs associated with long-term use. This is because shingles are simple to replace, and water leaks are easier to locate than on flat roofs. Lastly, pitched roofs are less likely to leak due to their ability to shed water quickly after it rains.

Types of Pitched Roofs

Mono-pitch roofs

Also referred to as “lean-to” roofs, mono-pitch roofs are the purest form of pitched roofs. Mono-pitch roofs should only span a short distance, and they are a popular choice for garages and sheds.

Couple Roofs

Couple roofs are simple roofs that include rafters and a ridge beam. However, they are not often used because of their lack of lateral support which can lead to roof failure.

Collar Roofs

Collar roofs are similar to couple roofs, but they include a collar to help prevent roof spread, a common problem with couple roofs. However, the collar roof doesn’t work for structures with spans larger than 4.5 meters.

King Post Truss Roof

King post truss roofs have additional supports including a king post and struts. They are often used for projects that require a larger span.

Mansard Roofs

Mansard roofs have complex rooflines, meaning that they have more than one pitch. They also have the added support of a king post. They are used most often when homeowners require additional space under the roof (such as attic or storage spaces).

Modern Truss Roofs

Modern truss roofs are the most common roofs in modern roof construction. Their supports include webs for bracing, and they come pre-manufactured from a roofing company. Modern truss roofs are the easiest type of roofs to install, though it is still recommended that someone with significant roofing experience install them.

What to Do?

Flat roofs are often associated with more modern design, while pitched roofs are more practical choices for areas that receive a lot of precipitation. Homeowners have both design and practical things to consider when deciding between a pitched roof or a flat roof. However, generally, flat roofs are more appropriate for areas that receive little rainfall, and pitched roofs are more suitable for wetter climates due to their ability to resist moisture damage.



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