low slope roofing

Understanding low slope roofing

Roofing is generally broken down into two types: steep-slope roofing and low-slope roofing. A roof pitch of 3/12 or lower is considered low-slope while 4/12 and above is considered steep slope. (For an explanation of the term “pitch” and other terminology, please see our FAQ page) Composition roofing shingles and cedar shake are examples of steep slope roofing products, while single ply membrane materials are used for low slope roofing. Low-slope roofing is typically referred to as “flat roofing” even if the roof isn’t completely flat. Thus, low slope roofs are called flat roofs by most roofers. Around 10% of the roofs in the Seattle area are flat roofs.

Low slope roofing materials

Some of the most commonly used materials are Torch Down, Hot Tar, EPDM, TPO and PVC. Valentine Roofing proudly installs TPO and PVC low slope roofs over the other products listed. In an effort to familiarize you with each product, here is a brief run-down:

Three flat roofing products that Valentine Roofing does not recommend or install:

1.Torch Down Roofing: As the name suggests, torch down roofing is laid down with an open flame or “torch”. This torch is basically a mini flamethrower that melts the layers of torch down together. Not too long ago, torch down was widely used here in Seattle. Nowadays it is becoming more obsolete due to better products being introduced into the marketplace and the high insurance premiums needed for roofers to install it (many buildings have burned down during installations). For these reasons Valentine Roofing opts not to install torch down roofing.

Applying a torch down roof.

2. Hot Tar Roofing: Hot tar is another product that like torch down, is becoming obsolete in the Seattle residential roofing market. In traditional Hot Tar roofing, the tar is melted in a tar kettle, poured into a large bucket and then applied to the tar paper with a mop. The roofing product used with the hot tar is basically like the torch down material. The difference is that with the torch down, the tar is in the material already. With hot tar, the tar is mopped on during the installation. Both roofs usually last 10 years or so which is a short life span for low slope roofs. Valentine Roofing does not install hot tar roofs.

Applying a hot tar roof.

3. EPDM Roofing: EPDM stands for Ethylene Propylene Diene Monomer and is basically a rubber roof. This product is most popular in the Northeast part of the country and isn’t a very common residential roof in Seattle. If installed correctly, EPDM can last 10-20 years. However this is a very big “if”. EPDM roofing relies on adhesives or bonding agents to keep each seam of overlapping roofing from leaking. If the bonding agent isn’t applied just right, you will have a leaky roof. There is also a common problem with bubbling when the EPDM isn’t laid flat enough. Because EPDM is cheap and easy to purchase and doesn’t require specialized equipment to install, many roofers try their luck at this product and unsuccessfully so. The bottom line is: There are better options out there than EPDM.

A failing EPDM rubber roof.

Two flat roofing products that Valentine Roofing does recommend and install:

1. TPO Roofing: Thermoplastic Polyolefin or TPO is a single ply roofing material that is highly resistant to tears, impacts, and punctures with good flexibility to allow for building movement. TPO is also known as the most reflective and cool roof particularly in the color white. Each seam is heat welded which essentially creates one solid, seamless roof as the finished product. Seam strengths with TPO roofing are typically three to four times those of EPDM's adhesive bonded seams. Because of its relatively low cost, durability and long life span, (over 15 years) TPO is a very popular choice for Seattle roofing contractors. As such, Valentine Roofing proudly installs TPO roofs.

TPO roofs are among the most heat-reflective.

2. PVC Roofing: Hands down the best low slope roof is PVC. PVC roofs stay flexible over time which is the main characteristic that is quickly making PVC the most popular low slope roofing option in Seattle. As soon as a low slope roof becomes rigid, it will crack and leak. Low slope roofs are very unforgiving and can leak with even the slightest cracking. PVC roofing is highly- engineered to be supple, strong and reflect UV rays that break down flat roofs. The flexibility of PVC roofing also makes it easier for roofers to install the product around roof penetrations like vents, chimneys and skylights. PVC roofs can easily last more than 20 years.

PVC roof installation.

Which manufacturer is recommended for PVC and TPO roofs?

WeatherBond Roofing Systems is the preferred brand by Valentine Roofing. WeatherBond is the most trusted name nationally for low slope roofs. In addition to manufacturing high quality PVC and TPO roofing, their product line also includes a full line of accessories for each system.

Valentine Roofing is a WeatherBond Recognized Contractor. This means that every WeatherBond roof that Valentine Roofing installs comes with a 20 year extended warranty. This means that along with your Valentine Roofing workmanship warranty, WeatherBond covers both the labor and materials of your new Valentine Roof. This way you are covered by your local Seattle roofing specialist and a national brand.