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How to waterproof the exterior of your Portland home

The Pacific Northwest is known for its wet climate. While 36 inches of annual rainfall is great for the lush greenery, it can also present a challenge to homeowners. Water leaks in your home’s siding can result in major damage and cost thousands of dollars in repair. That’s why it’s important for you to make sure your Portland home has a waterproof exterior that can hold up against the infamous Pacific Northwest weather.

At Lamont Bros. Design & Construction, we’re no strangers to home exteriors. Our team has performed hundreds of home remodels across the Portland area, including dozens of additions and exterior renovations. We know how to waterproof an exterior — in fact, many of our Portland remodel projects feature exterior waterproofing warrantied for 50 years. 

If you want to know what it takes to properly waterproof the exterior of your Portland home, you’ve come to the right place. In this article, we’ll cover everything you need to know about installing a weather-resistant barrier (WRB) that keeps your home safe. You can expect to read about:

Why is exterior waterproofing so important in Portland?

When it comes to your home’s exterior, waterproofing is so much more than just keeping out the water. We use the term colloquially, but a properly installed exterior envelope shouldn’t just be waterproof — it should keep out pests, prevent rot, and insulate the home.

Preventing water damage

Because of the constant rainfall, your home will probably spend a lot of time being wet. Unfortunately, if rainwater sits in the wrong place for too long, it can cause parts of your home to warp or even rot.

 In Portland, dry rot is an especially common issue in homes without a waterproof exterior. The issue with dry rot is that it can spread deep into your home’s structural members. Once inside, it rots away the studs and beams that support your home. Repair on dry rot is also costly because it often requires stripping areas of the home down to bare studs and replacing everything affected by the rot. In some cases, dry rot repair can cost over $100,000. 

When it comes to water damage and dry rot, an ounce of prevention is worth a pound of cure. A good exterior waterproof system may not be the most glamorous feature to include in a remodel, but it will help prevent expensive repairs in the future.

Energy-efficient heating and cooling

An effective weather-resistant barrier also prevents air from traveling through the walls of the home. Your home should hold its air in as much as possible. When the weather-resistant barrier isn’t properly sealed, air will be able to travel between the inside and outside.

Escaping air means a transfer of heat energy between the inside and outside air. When this happens, your heating and cooling systems will have to work harder to maintain the home’s internal temperature. As a result, your end up spending more on your utility bills. 

Though it is a sizeable investment up front, paying to upgrade your exterior waterproof barrier could save you hundreds of dollars annually in power costs. The US Department of Energy estimates that 40% of home heating costs are due to air leakage. So, if you’re looking to cut back on your power consumption, your WRB might be a good place to start. 

What is the best way to waterproof your Portland home’s exterior?

Due to the constant rainfall, building a waterproof exterior in Portland often involves more steps than it might in other regions. At Lamont Bros., we’ve built exteriors that we warranty for 50 years. Below is a method we have used to ensure our clients’ homes remain protected from the elements.

Huber Engineered Zip-System Plywood Sheathing

The first step in our process is to install Zip-System plywood sheathing on the home. This product offers excellent protection as a last line of defense against the elements. 

Traditional sheathing methods involve installing oriented strand board (OSB) or plywood sheets to the exterior of the home and covering it in a house wrap membrane. Zip-System simplifies this process by combining the sheathing and membrane into one. 

The engineered wood material used as the base for this sheathing has much greater water resistance than OSB or plywood thanks to resins used as a binding agent. This makes it less prone to warping and rot, while still remaining waterproof. 

Zip System sheathing attaches to the exterior of the home.

Zip System Seam Tape & Liquid Flashing

Zip System Seam Tape (black)

Once the sheathing is installed, we then apply seam tape to cover the gaps between the sheets. This creates a waterproof surface from wall to wall and prevents water from getting between the sheathing boards.

In addition to the tape, we also use a liquid flashing product to fill in nail holes and intersections where the sheathing connects to the frame. The liquid flashing is made of a silicone-polyurethane hybrid material that is both waterproof and extremely durable.

 It’s a great addition to a waterproof exterior wall because it applies as a liquid, allowing you to seal irregular or hard-to-reach surfaces. When paired with seam tape, you’re left with very few openings in your home’s exterior for air or water to pass through.

Benjamin Obdyke Slicker Classic Rainscreen

BenJamin Obdyke rainscreen before siding installation

Over the top of the Zip-System sheathing, we’ll typically add a rainscreen. The Benjamin Obdyke product is a 3-dimensional, vertically-channeled rainscreen that offers several benefits to an exterior waterproofing system.

A rainscreen provides an air gap and drainage channel between the sheathing and siding. This is a very important feature, especially in the Portland area, because the rain screen directs water down and away from the home. Without it, water that gets behind the siding could get trapped, resulting in water damage and possibly even rot.

Exterior Siding (You Get to Choose!)

Once the rainscreen is installed, the exterior siding goes over the top and provides the outermost layer of the waterproofing system. The exterior siding takes the hardest beating when it comes to rain and weather. You’ll want to choose carefully when it comes to your exterior siding — it makes up a bulk of the home’s visual style and acts as the waterproof system’s first line of defense.

In the Pacific Northwest, some of the most popular types of siding include cedar, fiber cement, and engineered smart siding. The 50-year exterior warranty mentioned above involved LP Smart Side, an engineered wood siding product. While the product has a warranty of 50 years, if maintained properly, it can last for over 100 years. 

Different types of sidings have different strengths and applications — what works for one homeowner might not work for another. Check out this article to learn more about the different types of exterior siding. 

Ready to talk to a professional about how to waterproof the exterior of your Portland home?

Now that you understand more about the importance of a waterproof exterior and what goes into it, keep up your research. To learn more about remodeling and building home additions, check out our Addition Portfolio. There, you can find photos of past Lamont Bros. projects and star gathering inspiration for your own remodel. 

Do you want to start talking with a professional remodel designer about remodeling your home? If so, click the link below to connect with a member of our professional design team. We’ll guide you through the challenges of remodeling so you never have to face them alone.