Build a Perfect Pergola

How to Build a Perfect Pergola | While this weathered pergola at Benson Park looks challenging to build, you should think of it like eating an elephant. Pachyderms are best eaten one bite at a time. Copyright 2023 Tim Carter

How to Build a Perfect Pergola - It Starts With Planning

A few days ago I took my American Dirus dog for a walk in southern New Hampshire while my wife was shopping for plants with my son. Willow and I went to Benson Park, an old zoo in Hudson, NH that’s now a marvelous city park. It was alive with the laughter of children and I could sense the excitement that hundreds of thousands, maybe millions, of people who had walked the same pathways over the past seven decades. All those years ago they were about to see camels, alligators, bears, elephants and many more exotic animals.

Click here to see exotic Willow that looks like a wolf but has NO wolf DNA in her.

Park benches were as abundant within the park as popcorn would have been on a summer’s day. One particular one caught my eye as it was nestled under a weathered simple, yet elegant, pergola.

Rough Sawn Cedar is Exceptional

While Willow was using her nose to make a mental note of all the other dogs who had been to the same spot, I used my eyes to capture the timber eye candy. I thanked the architect or carpenter who had come up with the idea for the pergola’s interlocking 5/4 x 10 rough-sawn cedar used to create the shade screen that measured 12 by 16 feet. It was the perfect size in my opinion.

pergola interlocking roof shade screen cedar wood

The pieces of wood that create the shade screen interlock with notches created in the top and bottom of the timbers. Think about how cardboard does the same thing to make spacers for glassware. Copyright Tim Carter 2023

As strange as it seems, the first thing that I noticed was the extra simple trim lumber that had been used to fatten the four support posts. While it was unnecessary, this small touch created both visual appeal as well as a subliminal message of strength. Think about an elephant’s lower legs compared to a gazelle’s. The elephant telegraphs sturdiness, power, and stability.

Only Paint if your Pergola is in the Atacama Desert

Fortunately, no one had ever painted this masterpiece. Painted exterior wood almost always peels. The expansion/contraction coefficient of the wood is much greater than that of most paints. To prevent paint from peeling, you need to keep it dry. This is why you rarely see painted wood inside a home peel. But put that same piece of wood outdoors where water can get on it and you'll have peeling paint in no time. The wood used for a pergola is exposed to every drop of rain. Never ever paint a pergola unless it's located in the Atacama Desert where there's been no recorded rainfall for hundreds of years.

I’m sure the Benson Park pergola had been stained at one time but that was years ago as the cedar wood now sports a distinctive gray color much like my own hair. It’s vital the park staff clean and seal the wood soon in my opinion. Water and sunlight will eventually take their toll and the majestic pergola could end up as dumpster fodder or kindling wood.

When you seal your pergola, or any outdoor wood, always try to use a penetrating sealer made with synthetic resins. You also want one with a medium color. The color pigments act like sunscreen sacrificing themselves to the ultraviolet (UV) rays that contain photons. Keep in mind penetrating wood sealers don’t peel like film-forming sealers that seem to dominate the marketplace.

Film-Forming Sealers are BAD

The cynic in me thinks the sealer manufacturers promote film-forming sealers because when they fail, your deck, pergola, or outdoor wood furniture looks horrible faster. This means you need to buy more sealer in fewer years.

If you plan to build a pergola this summer like the one I saw at Benson Park, you only need a few tools. But before you buy any lumber, you need to visit your local zoning office to see if you’re even allowed to build one. Some cities, towns, and even HOAs have very rigid and restrictive codes that limit what you can do on your own land.

What Will Happen Under the Pergola?

Once you know you’re allowed to construct your pergola, it’s time to think about its primary purpose. Will it be simply decoration or will it be functional? What will you do under it? Sip an iced coffee, read a book, play harmonica, set up your outdoor amateur radio, or play chess? Give thought to the furniture you’ll need and make sure it fits with ease under the structure. You don’t want to be bumping into the support posts.

I can’t stress enough the importance of this planning step. All too often folks think a certain size will work because the space seems so large. But as you start to move furniture in, the large space shrinks more than a golf glove that gets soaking wet and then dries in the sun.

Stainless-Steel Fasteners are Best

Spend the extra money to use stainless-steel nails, screws, bolts, and nuts. Beware of cheap electroplated galvanized hardware. It looks great but that ultra-thin coating of zinc wears off faster than a two-week honeymoon. Once the metal begins to rust, it can permanently stain your expensive cedar or redwood.

Don’t underestimate the power of the wind. You’ll thank your lucky stars that you attached the pergola to concrete piers using hold-down anchors when you get an alert on your phone about an approaching severe storm packing wind gusts of 50 mph or more. The last thing you want is to see your pergola lift up off the ground and float or tumble into a neighbor’s yard.

I feel my best piece of advice is to go hunting for pergolas near your home. You might find them at garden centers, city or county parks, or in public gardens. Take your tape measure and notebook with you. When you spot one that makes you melt, it’s time to take measurements, photos, and even sketch it so you can re-create it in your backyard. Don’t try to reinvent the wheel, it’s better to just copy one or tweak one that you already love.

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