How to add a pergola to an existing deck?

My advice would be to check with your county building codes to see if you can build it and if a permit is required, also check with a homeowners association and your homeowners insurance company. We required none of these since the structure was 12x12 and lower than the roof line of the home that it is attached.

My experience: We added a pergola to our concrete patio using a kit purchased from Costco. The kit included instructions for both concrete and wood installation. The instructions were available online (without purchasing) and stated what additional items needed to be purchased depending on the type of ground (concrete, wood) you plan on installing the pergola over as well as attaching to another structure. We purchased the kit which was basically plastic sleeves that cover the 4 wooden posts plus the rest of the structure and concrete attachment bracket kit from Costco, 4x4 wooden posts from the hardware store that set into the the brackets plus I think 4 other wood pieces that were covered by plastic sleeves for a total cost of about $1200. It took us 2 days to assemble and then the roof was another day. The roof was a separate purchase of materials for about $100. It's a somewhat clear wavy plastic to protect from the sun uvs. Costco delivered the kits to our house in 16 boxes so be ready for that. It has been 3 years and I still love it. The best part is that it cleans off with a hose even on areas that turned green over the winter and doesn't chip so no painting/staining required.

It looks a bit like this one but ours is smaller:

https://www.costco.com/Valencia-12'-x-16'-Attached-Pergola.product.100243910.html

Vicki - I had the same situation. I bought the metal pergola at Lowes and had it anchored to the deck. Worked great.