Which Roof Material Is Best on a Low-Slope Roof Near the Ocean?

Are you worried that living near the ocean or having a low-slope roof limits your roofing options and that choosing the wrong material could lead to rust, leaks, or premature roof failure? Have you been told that asphalt shingles are "good enough" for a low-slope roof while others say they’re not, leaving you unsure what to believe?

At RoofSmart, we pair hundreds of homeowners every year with the right roof material for their home by taking into account their budget, aesthetic preferences, and their roof’s needs. It’s our goal to be upfront about the pros and cons of each product so that you can make an informed decision.

In this case study, we'll explain which roofing materials perform best on low-slope homes near the ocean, why some products fail prematurely in Seattle's coastal climate, and what one Gig Harbor homeowner did to protect their home with a roofing system built to withstand both salt air and standing water.

Seattle Coastal And Low-Slope Roofing Problems and Solutions

Can you install a steel roof on an oceanfront home?

Steel is not naturally corrosion-resistant, so if you want to install it on your home near the ocean, then you need to make sure that it is protected with the right type of coating.

Recently, we installed a steel standing seam roof for a customer living in Gig Harbor. She originally had an asphalt shingle roof, but wanted something that she wouldn’t have to replace again in another 20 to 30 years.

Here’s how it turned out:

We gave her some recommendations, and she chose steel. And since steel is prone to rusting, especially in the salty ocean air, we made sure to order the panels with the manufacturer’s marine-grade coating that even comes with its own warranty.

A lot of Seattle homeowners are hesitant to install a metal roof on their home near the ocean because they worry that it might rust. This is a valid concern, but as long as you choose the right material and take the proper precautions, then a metal roof can work great.

What other precautions should you take when installing a steel roof on a home near the ocean?

The protective coating works great on the steel panels, but if your roofer has to cut the panel and leaves the cut edge exposed to the ocean air, it becomes vulnerable to rusting.

It’s important to make sure that you hire an experienced roofer so that there are no exposed cut edges.

A roofing contractor who has installed several roofs near the ocean knows that you need to take extra precautions to protect the exposed edges of the panels. They also make sure that every detail is taken care of, like using marine-grade screws that won’t rust.

At RoofSmart, we’ve installed hundreds of metal roofs, including many on homes along or near the ocean. As a result, this customer knew that she could trust us to get the right kind of material and do a top-quality installation.

This expertise, paired with our recommendations for protecting the steel panels from the ocean air, confirmed to this customer that we were the right roofing company for her.

Will a metal roof work on a home with a low slope?

The other concern we had with the house in Gig Harbor is that it had a low-slope roof, which means that you need to be cautious about which roofing material you choose to use. Metal roofing can be installed, but it needs to be mechanically seamed.

A lot of low-slope roofs in the Seattle area have asphalt shingles on them, but this is one of the worst options you can choose because asphalt shingles absorb moisture and take forever to dry out. Plus, they are not meant to handle standing water.

When they’re installed on a low-slope roof, especially in a rainy, humid area like Seattle, they retain moisture, deteriorate prematurely, and start leaking like crazy.

Even though manufacturers say that you can install asphalt shingles on some low-slope roofs, we don’t recommend them on anything lower than a 4:12 pitch.

Our customer had asphalt shingles on her low-slope roof, and we ended up needing to replace pretty much all of the plywood decking on the roof because it was all rotten. The asphalt shingles were very worn out, and some parts of the roof were growing a lot of moss:

We also ended up tearing off the siding around the chimney because it was incredibly rotten. We built a new chimney chase to go around it.

Metal is the nicest-looking of all the options that you can put on a flat roof. You can choose to install these materials:

• Torch down
• PVC
• TPO 

However, our customer did not like the way that any of these looked, so she chose mechanically seamed metal panels. This means that after the panels were installed on her roof, we went over every seam on the roof with a special tool to fold the seams over multiple times.

Mechanical seaming is a great way to ensure that your metal roof is watertight. It is ideal for low-slope roofs because they don’t drain as well and tend to collect water more easily.

Here’s a video of one part of the roof being mechanically seamed:

Mechanically seamed metal roofs are more expensive and take longer to install, but after dealing with asphalt shingles, our customer was happy to invest in a roof that would provide superior protection on her home for a long time.

Comparison Table: Best Roofing Materials for Low-Slope Oceanfront Homes

Is a metal roof really the best choice for a low-slope roof?

As you've seen, choosing a roofing material for a home near the ocean with a low-slope roof requires balancing several factors at once. Salt air, standing water, wind-driven rain, and poor drainage can all shorten the life of the wrong roofing system.

While marine-grade mechanically seamed metal proved to be the right solution for this Gig Harbor home, it isn't automatically the best choice for every low-slope roof. Some locations make more sense with a more premium material, such as copper or aluminum, depending on the level of salt spray.

The roof's pitch, your home's location, your budget, and your long-term goals all play an important role in determining whether metal is the right investment.

Read next: Can You Use Metal on a Low-Slope Roof?
https://getroofsmart.com/blog/metal-on-low-slope-roof

In this article, we'll take a deeper look at when metal roofing is appropriate for low-slope roofs, explain why mechanically seamed panels are often required, and compare metal to other low-slope roofing options so you can confidently choose the best system for your home.