Which Roof Beam Material Is Best for You? Parallam vs. Glulam vs. Steel

Are you trying to choose the right roof beam for your home but feeling unsure which material will hold up best in Seattle’s rainy climate? Does the idea of spending thousands on a structural beam that might warp, rust, or require constant maintenance make you nervous?

At RoofSmart, we do more than just install shingles on your roof. We also do carpentry and framing work on flat and sloped roofs. We’ve helped over 100 customers resolve framing issues on their roofs and choose the materials that work best for them. 

In this article, we’ll compare parallam, glulam, and steel roof beams by breaking down the pros, cons, and price considerations of each type of beam. 

You’ll learn which beam performs best in moisture-heavy conditions, which offers the best aesthetics, and how to decide which option makes the most sense for your roofing project and long-term goals.

When is a parallam roof beam right for my Seattle home? 

Image from Great Central Lumber

Parallam (parallel strand lumber) is made of long wood strands that are glued and compressed together. This method makes the beam consistently solid and strong.

Pros: 

• More stable: Parallam is made of a bunch of smaller pieces of wood that are compressed together. This makes it less likely to act like natural wood, which dries out over time and can warp. Parallam rarely has this issue.
• Can be modified easily: Parallam is more adaptable because it can be cut or modified on-site without risking the structural integrity of the beam. 

Cons:

• More expensive: In most cases, parallam costs more than glulam. One factor that increases the price is that people often choose to wrap it, which adds to labor and material costs. 
• Rough texture and appearance: Parallam isn’t everyone’s style, so you might want to cover it up. It looks like OSB, which is usually not popular for its appearance. You typically plan to paint it or wrap it with an exterior trim, like cedar. 

Why do Seattle homeowners choose glulam roof beams? 

Image from Timberlab

Glulam (glued laminated timber) is made of a bunch of 2” x 6” (or similar, more traditional-looking dimensional lumber boards) glued together. It still has a lot of the same features of real dimensional lumber, but it's a lot stronger than if you just got a 4” x 16’ piece of wood because it's laminated into different layers.

Pros: 

• Aesthetically pleasing: A lot of people like glulam as is because it has the classic wood grain look. If all you wanted to do was stain or finish it, it would look great. 
• Easier to stain and finish: Because of the way glulam is made, the process of staining it is much smoother. 
• Cheaper than parallam: Typically, glulam is the less expensive choice because it is easier to make. The only exception to this is some higher-end varieties of glulam that can be more expensive than parallam. 

Cons: 

• Might twist or bow over time: As wood dries out, it can twist or bow. Unfortunately, that’s just how wood is. Glulam is potentially susceptible to this because it is made of several long pieces of wood that can warp. 
• Limitations for modification: Glulam is made to be used as is. You’re not supposed to cut it or make other modifications to it unless you have approval from an engineer. 
• May need to be pressure-treated: If it’s in a place to receive direct water, like an outdoor exposed patio cover, then the beam will need to be pressure-treated to protect it from rotting.

Is a steel roof beam a good option for my Seattle home?

Image from Service Steel Warehouse

Steel is a popular alternative to using wooden beams. These beams are long and have a distinct shape that looks like a capital “I”, which is why they are commonly referred to as I-beams (except this does not translate over very well in every font). 

Pros: 

• Strong and lightweight: Although steel beams are lightweight, they are still strong and durable enough to be used as beams. 
• Smaller than wooden beams: Steel beams are usually smaller than wooden beams. This is useful if you don’t want the beam to be visible in your home, but you don’t have a ton of space to work with. 
• Versatility: Steel beams can easily be cut and modified to fit the structure of the building that you are working on. 

Cons:

• Susceptible to rusting: If the beam is used in a humid, moist environment, it will be prone to rusting. This can be prevented if it is properly coated (in the same way that a metal roof made of steel needs protective coatings). 
• High maintenance costs: In order to prevent rust, you need to regularly reapply paint coatings. This can get expensive, but it will make sure that your beam lasts for a long time. 
• Not aesthetically appealing: It really needs to be concealed by a trim wrap for appearance, unless you’re going full industrial or loft style. But it’s more difficult to do this, because you can’t nail into it. This is a major reason it’s often recessed into the structure or ceiling rather than left exposed.

How much do roof beams cost in Seattle?

Parallam and glulam beams typically cost around $20 to $30 per foot, with parallam on the higher end of the cost spectrum. The steel beam costs about the same amount. 

However, this is just the cost for the beam itself. You also have to consider these other factors when calculating the total cost for the wooden beams: 

1. Labor to install the beam 
2. Labor and material costs to wrap or finish the beam

How do I know which beam material is right for my Seattle roofing project?

Most of the time, Seattle homeowners choose the glulam beam because it is a bit cheaper and it looks nicer. It’s easier to stain and finish, so you pretty much instantly have a nice-looking beam. 

Roof replacement costs in the Seattle area are on the higher end, so homeowners often choose the lowest cost option. 

However, make sure you take into consideration what’s best for your budget and needs. For example, if you’re in a wet environment, the wooden beams might be at risk of rotting. So, you can choose to use a steel beam. 

Or, if you want a durable option that will maintain its shape and can easily be modified, then parallam or steel are good options. 

What should you expect to pay for a new roof in Seattle?

Understanding the risks and costs of different options for beams to reframe your roof is only one part of the equation. 

If you're starting to wonder what a full roof replacement might cost in Seattle, especially with today's labor rates, material options, and moisture-heavy climate, you're on the right track. If you need to redo the framing in your roof, that means you're replacing the entire roof. 

Whether you’re budgeting ahead, comparing quotes, or dealing with roof damage that’s beyond repair, it’s important to understand what the average Seattle homeowner is actually paying for a new roof.

Read our article “How Much Does a Roof Cost in 2025? Prices for Seattle Homeowners” to learn how much your new roof will cost and the factors that increase prices (like installing a new beam).