Pergolas are a great backyard addition, and we field a lot of questions about the best lumber to use when building this type of outdoor structure. Our top two recommendations are always the same: western red cedar or Douglas fir.

Western Red Cedar Pergolas

Cedar is our number one choice for pergola lumber because we believe it’s the ultimate outdoor building material. It’s beautiful, takes stain and finishes well, and is dimensionally stable — so it won’t twist and warp like other types of lumber. It’s also light, making it easier to work with. 

Douglas Fir Pergolas 

While we’re partial to cedar pergolas, it’s not the only option. Another beautiful species is Douglas fir. Just a few notes about this sturdy species: 

• Douglas fir is much heavier than cedar, so you might need an extra pair of hands during the build.  
• Use free-of-heart-center posts to help prevent twisting and warping. 
• Douglas fir might check or crack as it dries but don’t worry, it won’t affect the structural integrity.  

Dressed or Rough Lumber? 

If you’re using a pergola kit or post brackets, make sure to read the lumber specifications. Many products (including the popular Toja line) are designed to work with dressed lumber. This means that the actual dimensions are smaller than the named dimensions. For example, a 4×4 dressed post doesn’t actually measure 4” by 4” – it measures 3-½” by 3-½”. 

If you’re building a pergola from scratch and using hardware like the Outdoor Accents collection from Simpson Strong-Tie, you can choose either dressed or rough lumber. Both are structurally sound, it’s more of a design preference. 

Interested in learning more about pergola hardware? We’ve outlined the benefits of Toja Grid brackets and Simpson Strong-Tie hardware in our article, Pergola Hardware Options.

Other Wood Options

Another option is pressure treated lumber. This is the most cost-conscious lumber of the three, but a word of caution: it can be tricky to stain pressure treated lumber and it is more susceptible to cracking and twisting. 

Tips for Finishing Pergola Lumber

• CUTEK is one of the best finishing oils for cedar and Douglas fir. It’s a deep-penetrating oil-based wood stabilizer that helps minimize warping, cupping, and splitting. To help prevent UV damage, add a Colourtone (there are 18 colours to choose from) to protect and enhance the natural beauty of the wood. 
• While some people apply a finish before assembling the pergola, we find it’s easier to wait until the pergola is assembled. It’s easier to reach all four sides and allows for even drying.  
• Always wait for a hot day to apply CUTEK and allow it to fully penetrate before applying a second coat. Thin coats are better. 

Whatever lumber you choose, we have everything you need to build the perfect pergola for your outdoor escape. We sell dressed and rough cedar and Douglas fir and stock both Toja and Simpson Strong-Tie hardware. We’ve even created Toja pergola kits that include everything you need to build a pergola on a weekend.  

If you have more questions about cedar, Toja, or Simpson Strong-Tie hardware, don’t hesitate to reach out. We can answer any questions you have or put together a quote for materials. 

If you’re ready to start building, shop for our pergola options online or send us an email and we’ll get an order put together for you!