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House One editor Jenn Largesse continues her backyard renovation project. After installing beautiful composite decking and handrails around her shipping container pool, Jenn works with a contractor to install a vinyl pergola with aluminum reinforcement on her pool deck.
Footing choices can also influence overall project cost. On a recent This Old House project, the team used pre-cast footings buried four feet deep in the ground rather than pouring concrete into forms on site. As Roger explained on that build: “They brought them to us just like this. We hook them up to the Bobcat, dig down to the right height, and simply just lower them down in place.” Prefabricated footings can streamline installation time but may add to material costs depending on the number of posts your pergola design requires.
How to Build a Pergola
- Start by laying all of the individual parts to the pergola kit out and take inventory of what’s there. Be sure all of the parts and hardware are included. Also, if the weather was chilly overnight, allow the vinyl to warm a bit in the sun to prevent possible cracking.
- Slide the aluminum rafters and support beams inside the PVC sleeves and use the PVC glue to attach the end caps.
- Place the two support beams together to be perfectly even on the ends. Starting in the center, measure and mark the beams at 16-inch intervals and attach brackets at these points.
- If the pergola will integrate into an existing railing, detach the railing from the existing post. Pad the existing wood post with 2×6 lumber to build it out to the width of a 6×6 (this will require trimming one 2×6 to width).
- For new decks, plan ahead and attach extra 4×4 blocking between the joists at the locations of the posts before installing the decking. For existing decks, it may be necessary to remove the decking boards or access the deck from underneath to add support. In either case, use lag screws driven through the joists and into the blocking to hold them in place.
- Place the aluminum posts in place on the decking and lag them into the blocking using the impact driver and the lag screws included in the kit. Slide the collars over the posts followed by the vinyl sleeves.
- Clamp scrap pieces of lumber to the posts at the correct height for the support beams. Place the support beams on the scrap lumber and attach them to the posts using the hardware in the kit.
- Lay the rafters across the support beams and situate one at every set of support brackets. Screw through the bracket and into the rafters to hold them in place.
- Lay the shade slats on top of the rafters and space them evenly. Screw through the top of each shade slat and into the rafters to hold them in place.
When installing the pergola onto brackets, keep the back of each purlin a good ¼ inch from the siding to allow for expansion and water drainage. Use a combination bit to bore angled pilot holes through the sides of the rafters and into the brackets before driving deck screws to fasten the pergola in place.
During a This Old House project in Westerly, Rhode Island, pergola contractor Mark Bushway demonstrated how cellular PVC columns — solid all the way through — can actually be milled with the same router bits used for wood. Because the material is solid, builders can use many of the same fasteners, molders, and routers they would with traditional lumber, but the columns for a larger structure like a pergola need internal aluminum reinforcement to carry the weight.
Resources
Jenn and Luke from Dream Decks tour her deck built from Trex Decking in Havana Gold with universal hidden fasteners and Trex Transcend railings in Classic White with square white balusters, post cap lighting, and stair riser lights. Together they install a steel-reinforced vinyl pergola manufactured by Superior Plastic Products and sold by Plastic Lumber Yard.
