Picture-Perfect Pergola
Built from locally sawn hemlock, this functional outdoor feature uses structural screws and metal connectors for fast, sturdy construction.
Builder Jeremy Kassel shares how he constructed a sharp-looking, durable pergola using locally sourced hemlock and Simpson Strong-Tie hardware. Instead of traditional joinery, he used decorative structural screws and metal connectors for faster assembly and a clean look. Thoughtful choices — like using planning software, forming square concrete footings, and mocking up the purlin layoutâhelped speed up the process while ensuring long-term stability. The result is a low-maintenance, good-looking outdoor structure that balances ease of build with strong performance.
Pergola Perks
A pergola is a great addition to a garden, deck, or outdoor living space. It can offer shade, complement an architectural design, or provide a structure on which grapes or hop vines can grow. My wife and I have wanted one for years, but as a hands-on contractor during the workweek and a busy dad to two kids always, I didn’t want to spend a lot of my free time building it.
A sponsored video for FineHomebuilding.com was the motivation I needed to get our pergola structure built. The sponsor, Simpson Strong-Tie, provided me with its Outdoor Accents metal connectors and fasteners. This black powder-coated hardware has decorative washers that make it look like a system of bolted connections.
In reality, the connectors use structural screws that don’t require drilling pilot holes. The system goes together quickly and creates a timber-framed look without labor-intensive hand joinery or special timber-framing tools. This hardware allowed me to complete the entire pergola in just three days. I’ve built pergolas using structural screws from other manufacturers and a combination of through-bolted and lag-screwed connections.
These methods of construction work fine too. You could also go the traditional route with timber-frame joinery, which I have not done. Assuming the pergola you’re building uses spaced purlins and not continuous roof sheathing, snow load is not a factor, so inspectors should accept common construction methods.
Plan for Sturdy Connections
No matter which method you use for connecting the framing, the pergola—which is naturally top-heavy—has to be built sturdy enough to resist flex and racking during high winds and when kids or adults are looking for a climbing challenge. If the load path connecting the roof and posts to the ground isn’t strong enough, the structure can break up or topple in high wind or when someone starts climbing it.
Our pergola isn’t attached to the house and is near the center of our property, so we didn’t need a permit, but rules vary by location. Many municipalities require permits for pergolas built on decks or when they’re attached to the house. In addition, outdoor structures built on permanent footings often must adhere to zoning-enforced setbacks from property lines. Check the rules before building to make sure you don’t have to remove the structure or make changes later.
Because a pergola has little surface area for catching wind (or “sail area”) and no live load, some amateur and professional builders may be tempted to simply set it on grade or on solid concrete blocks to speed construction or avoid zoning or building rules. I would insist on burying the posts at least 18 in. in the ground for better racking, overturning, and wind resistance. Embedding the posts in concrete provides even more wind and racking resistance.
Unfortunately, putting the posts in soil or concrete will keep them wet, making them rot quicker. To combat this, for my pergola I used raised concrete footings with post bases that prevent the wood posts from absorbing water. I dug the six 48-in.-deep footings by hand, choosing to excavate to frost depth so the structure would stay plumb and level. I find that cardboard building tubes are tough to keep level and their tops become oblong or delaminate when saturated, so I formed square tops for the footings using four 2x4s arranged to form a square in the center. It is easy to shim the ends of the 2x4s so that the top of the cured concrete will be level, and the resulting 12-in.-square concrete pier provides ample room for me to install post bases and square the building.
My helper and I prepared about 30 bags of ready-mix concrete in an electric mixer, placed it in the post holes and formwork, and gave it a smooth finish with a magnesium float. After letting the concrete cure for about 30 minutes, we steel-troweled and edged a second time. The following day we removed the forms and cleaned up the concrete’s sharp edges with a stone brick rub.
Finalize a Design
I created the design for this pergola using Simpson Strong-Tie’s Pergola Planning Software. The free, web-based program provides architectural plans, 3D elevations, and material takeoffs for lumber and Outdoor Accents connectors. I found the program easy to use and helpful for creating a design on my own. I suspect the renderings and material lists it generates would be enough to satisfy many municipal inspectors for building permits.
If you’re looking for design inspiration, FineHomebuilding.com has a lot of resources for building good-looking outdoor structures. The web is also loaded with images of attractive pergolas that can jump-start a design. I ask clients considering a pergola, trellis, or other outdoor feature to snap photos of any they like when they are driving around town or traveling.
When you’re thinking about siting or sizing a pergola, it’s important first to think about how you intend to use it. Many outdoor structures go unused because they don’t suit their intended purpose. When clients express interest in a pergola for outdoor dining, I suggest building it close to the kitchen. If they have an expansive property, it often makes sense to make the pergola a destination for walks. If shade is part of the design, I can test purlin spacing on a mockup to make sure it provides sufficient shade at the right time of day. I can mark out the footprint to see if it’s large enough for the collection of furniture planned for the space.
Once you have a design, you’ll need to pick the lumber to build it. The most readily available and least-expensive option east of the Rockies is pressure-treated yellow pine; in the West, it’s incised Douglas fir. PT works fine, and I’ve built a lot of decks and outdoor structures with it, but for this project we wanted something produced nearby with a natural color that wouldn’t require finish, so we picked hemlock from a local sawmill that was planed to standard dimensional lumber sizing. We had it planed so that we could use standard-length fasteners and standard-size metal connectors for joining parts of the load path.
Hemlock is abundant in upstate New York, where I live. I like it for outdoor projects because of its natural weather and insect resistance, and I think it looks attractive both new and as it ages. Red cedar is another common rot-resistant choice for outdoor structures and is available in clear and knotty grades. White oak, ipe, and black locust are also good choices.
As mentioned above, we chose not to apply any finish to the pergola and to let it age naturally, enhancing its rustic character. If you do plan on staining or applying a clear finish, talk to local painters for guidance.
My painting contractors and others I’ve talked to have favorite products for coating common outdoor wood species. I trust their advice, as they are familiar with what works locally.
Keep in mind that refinishing may be difficult or impossible if you choose to grow plants on the structure, which would necessitate removal or aggressive pruning.
Inside the posts, we laid down landscape fabric to block weeds and covered it with stone dust. Stone dust is inexpensive, and after it is watered it provides a stable surface for furniture.
Lessons Learned
If I had to do this build again, there is not much about it that I would change. I might have chosen to make the tops of the footings all level to each other, which would have made raising the posts easier—but then the amount of concrete footing above grade would not have been uniform, which is an aesthetic trade-off. I could also have leveled the site, but that wasn’t in my time or material budget.
My advice to anyone building a pergola or outdoor structure is to start with an accurate layout for the footings and post bases. Get that right and the rest of the build will be smooth and the framing will look correct, not crooked.
Mount the Bases
After using a similar process to find the footing locations, we made sure layout was dialed in before installing the post bases. To do this, we stretched a stringline parallel to a nearby cabin to align it with one side of the pergola. From there, we had to find the pergola’s planned 10-ft. by 12-ft. footprint and make sure that it was square.
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Raise the Posts
After setting the post bases, we use a rotary laser to establish a level plane for measuring the footing heights relative to each other. With the height of the footings determined, we can adjust the post lengths so the post tops are the same height.
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Cut and Fit Beams and Rafters
On the sides of the posts, 2x12s span the width of the pergola, creating beams on both ends for the rafters to bear on. Cantilevered overhangs add mass and balance for a pleasing look. The beams and rafter tails could be cut square or given a scroll, but we like the look of clipped corners.
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Add Braces
The diagonal knee braces for this pergola were made using the same 6×6 hemlock stock as the posts. These braces keep the entire pergola from racking laterally, as there are no walls with sheathing like there would be in a house.
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Top With Purlins
Shade and a climbing structure for vines are created by 2×2 hemlock purlins. You can adjust how much shade they provide by shrinking or widening their spacing. We decided 8 in. on center was the right amount of shade for our pergola, and we marked this spacing before installing the rafters.
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— Jeremy Kassel is the owner of Kassel Construction in Glenmont, N.Y. Photos by Andres Samaniego.
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