Can you put a pergola on a raised deck?

Are you making some renovations to your outdoor patio? If you’re an avid DIYer, an outdoor cover like a pergola is a great option. Perhaps you’ve seen people install freestanding pergolas on their outdoor patios. But, you have a deck on your patio. Can you put a pergola on a raised deck?

You can install a pergola on a low elevated deck as long as it has stable supports. For the best support, the banisters of your deck can support the pergola. They should run two to three feet into the ground and be set in concrete. In cold climates, dig three to four feet deep for additional support.

You can also install banisters through your deck to the floor, but it’s less common and can compromise the structural integrity of your deck. It’s recommended to hire a professional for the installation.

Another solution is to install supports on the deck itself, attached to the deck joists. Just make sure they can support the weight of your pergola. Use lightweight wood for the roof. On tall elevated decks, keep in mind that wind can be a problem. Make sure your pergola supports are securely attached to the joists in your deck.

Here’s a short video that walks through the installation process as well as some tips and tricks.

For a more fully involved walkthrough, check out the 90-minute video below. The homeowner installs the foundation for his deck along with the pergola.

Pergolas can be several hundred to several thousand pounds, so make sure your deck will support its weight. Each type of wood has different load-bearing properties. You can look them up online or ask a professional for help.

You’ll want to find out how much weight the wood your deck is made from can support per square foot. Then you multiply that weight by the square footage of your deck to determine the total weight your deck will support.

Most pergolas are eight to 12 feet off the ground. Keep in mind that this measurement is from the ground, not where your deck starts.

If you install a pergola that’s too tall, your deck may not support it properly. Also, in windy areas, the pergola could collapse! If you install a pergola that’s too short, it can be a fire hazard and be awkward to use.

You’ll also want the posts to be secure enough that guests can lean on them. You don’t want a guest to accidentally topple your pergola.

If you don’t want the trouble of ensuring your deck supports a pergola, you can install a free-standing pergola in another area of your backyard. Simple pergolas are DIYable with a little research.

Before you install yours, make sure it doesn’t cross property lines and doesn’t require a permit. Each city or county is different so contact your local government office to determine if your property requires a permit.

Here’s a short video that walks you through the installation process step-by-step.

Which decks cannot support a pergola?

A deck over water or soft ground cannot support a pergola. It will be unstable. It would take a contractor a lot of time and effort to ensure that the supports are stable and strong enough to support your pergola. Also, water and harsh weather can wear down these supports quickly. If you install supports in water, they can move over time causing the structure to collapse.

Use caution when installing a pergola on a tall elevated deck. The higher your pergola is off the ground, the more vulnerable it is to wind and harsh weather. One scenario where a tall elevated deck can more easily support a pergola is if one side is attached to the home. In this case, your home helps support some of the pergola’s weight.

On a tall elevated deck, the supports for the pergola need to be connected to the joists under your deck. You cannot use deck supports for the pergola because you end up with incredibly long posts. Long posts can introduce unnecessary sway and cause issues.

For example, if your deck is eight feet off the ground and you want an eight-foot pergola, you’d have 16-foot supports. That’s way too long to be safe, not to mention it may break building codes in your area. Supports longer than 12 feet can be quite unstable.

Here’s an example of how a pergola might look on an elevated deck.

Does a pergola need to be anchored?

Yes, a pergola must be anchored to the ground. The most secure option is to set your posts in concrete. You dig holes that are about ⅓ the height of your post and one foot wide. So if you have a 12-foot post, you’d dig a hole about four feet deep. Then you set your post in the hole, pour the concrete, and let it harden.

In cold climates, you may need to dig the hole deeper in the ground. Otherwise, the posts can become unsettled as the ground freezes and thaws over time. The point where the ground freezes is called the frost line. This point varies depending on where you’re located.

You can also anchor the pergola to the joists under your deck. On tall decks, make sure your deck wood is strong enough to support the pergola. Otherwise, the deck could collapse, which is catastrophic. Consult a building professional and you’ll have a much easier time installing your pergola.

That’s all for our post ‘Can you put a pergola on a raised deck?’ Low decks are OK but exercise caution when installing a pergola on a deck more than a few feet off the ground.

Click on the links below to get more of your outdoor renovation questions answered.

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