A pergola is a long, narrow outdoor structure that consists of two to four columns of pillars supporting a roofing grid of rafters and beams.
It’s often used to enhance the features of a garden/backyard, with the added benefit of protecting homeowners from harsh elements.
Though mostly built directly on the ground, some homeowners place the structure on a raised surface. But is this safe? Can you put a pergola on a raised deck?
In this article, I’ll discuss everything you need to know about pergolas on raised decks.
This includes essential dos and don’ts to ensure you and your family’s safety before and after the building process!
Yes, you can put a pergola on a raised deck as long as it’s strong enough to hold the weight of the entire structure.
On low elevated decks, the pergola’s banisters should be positioned at least two to three feet into the ground and be set in concrete.
On decks with higher elevations, the banisters can be installed on the deck itself. Just make sure the banisters are attached securely to the deck’s joists to prevent structural issues.
Some raised decks are more suited to hold pergolas than others, such as:
Traditional wooden decks are raised just a few inches off the ground so they’re level with the backdoors. They’re the sturdiest types of decks, with ample support from beneath.
These types of decks are usually made from pressure-treated wood to decelerate the process of deterioration and decay.
However, they’re not completely immune to warping, splitting, splintering, and eventually rotting, especially when constantly exposed to excess moisture.
As such, they require regular maintenance and sealing every with or without the addition of the pergola.
During installation, the deck’s preinstalled corner beams can be removed and replaced with the pergola’s vertical beams.
The beams should be dug two to three feet into the ground and stabilized with concrete for optimal support.
If that’s not an option, you can instead cut out square or circular holes into the deck’s existing boards and insert the pergola’s beams into them.
Concrete decks are often tougher than traditional wood decks, so they can easily support the weight of a pergola.
Installation is more of the same; simply cut through the concrete and sink the pergola’s beams into it.
You can also install the beams on top of the concrete directly, but this may pose structural issues if not done right.
Concrete decks don’t need as much maintenance as their wooden counterparts, but they still need to be resealed and retained at least once every other year with the pergola installed.
Composite decks are made from man-made composite lumber consisting of plastics, wood fibers, and bonding agents.
They’re slightly more expensive than wood decking, but offer greater durability and less maintenance.
Since they’re primarily made of plastic materials, they’re not as prone to damage from wood-destroying insects like termites.
They also don’t splinter as much as their wooden counterparts, so they’re perfectly suited for pergola installations.
When installing a pergola to a raised composite deck, a ledge board must be used. This board helps support the beams of the pergola.
Use a strong bolt to fasten the beams to the frame of the joists.
Though most decks can support a pergola, there are certain situations that make installation a little trickier than others. These decks are a little less likely to support a pergola:
Raised decks built over ponds, lake beds, or similar bodies of water can’t feasibly support pergolas atop them.
It isn’t impossible, of course; experienced contractors can make it work with a bit of extra planning.
However, it’ll require quite a bit of time and money to safely install a pergola over such a deck.
Moreover, the water currents could slowly sink the deck’s base deeper into the soil over time due to the pergola’s additional weight.
Caution must be used when installing a pergola on an elevated deck with tall supports.
The higher the pergola is off the ground, the less stable it’ll be. High winds and harsh weather can very easily compromise its balance.
Even if stability wasn’t an issue, installing a pergola on such a deck can be extremely difficult and costly.
Homes with tall, elevated decks rely too heavily on their support beams, making it near-impossible to replace said beams with the pergola’s own beams.
Freestanding pergolas aren’t an option, as they’re far too heavy to be positioned on top of stilted decks.
In such instances, there are two possible solutions.
The first solution is to fasten the pergola’s beams outside the deck’s existing beams and dug into the same foundation.
The second solution is to attach half of the pergola to the home. This way, the home supports some of the pergola’s weight.
Still, tall elevated decks aren’t the best candidates for pergolas, especially if the deck is over seven feet off the ground.
If the pergola is, say, eight feet tall and the deck is seven feet tall, you’ll need 15-foot supports at least. That’s way too long to be safe, especially if you live in an area with fluctuating weather conditions and high winds.
Supports over 12 feet can be quite unstable so you should be careful when constructing them on your property.
Now that we’ve discussed the types of decks that can properly hold pergolas, here are our top tips to follow during the installation process!
- Make sure the roof isn’t too heavy. If the pergola’s roof is too heavy, you might face stability issues. So rather than canvas cover or heavy wood, use fabric panels or light wood lattice for the roof.
- Similarly, make sure the roof isn’t too light. Since the pergola is installed on a raised deck, a too-light roof could be blown away due to strong winds.
- Opt for pergolas made of pressure-treated wood as much as possible to ensure long-term stability. Posts made of anything other than pressure-treated wood are vulnerable to wood rot or termites, making them expensive and time-consuming to maintain.
- Securely attach all four of the support posts to the joist structure under the deck rather than the floorboards. The floorboards must be either removed or cut into to make way for the beams. If you don’t, the pergola might tip over with the slightest gust of wind.
- If you’re not confident with the pergola’s stability, surround it with railings. Railings not only strengthen the structure of the pergola but also secure the space against accidental falls.
- Pergolas (and similar overhead structures) are subject to building codes, so always get planning permission before building a pergola on a raised deck.
- Don’t attach the beams to the decking board as merging wood to wood can cause stability issues. Instead, neatly cut the board and insert the post directly into the deck.
- If in doubt, always consult a professional. Though experienced DIYers can install a pergola on a raised deck, only a professional can guarantee its safety and stability.
Installing a pergola on a raised deck comes with several advantages, with the biggest being that it adds beauty and sophistication to a home.
With its brilliant sculptural and architectural design, it adds eye-catching visual interest to an otherwise standard deck.
Another benefit is privacy. Since the pergola is installed on a raised surface, it’ll shield you from the prying eyes of passersby and neighbors. Plus points if the deck is surrounded by railings.
Finally, a pergola installed on a raised deck can increase the value of your home.
Outdoor living has become more popular than ever, so homes with comfortable outdoor space can raise the price to about 50% to 80% for your ROI.
There are also the standard advantages of a pergola overall.
It provides shade from harsh sunlight and rainy weather, giving you a safe space to chill outdoors.
It can likewise lend support to other lovely landscaping features like ivy, vines, and climbing flowers.
They’ll weave their way through the pergola’s supports and roof beams.
These plants add further beauty to a home, making it appear lush and colorful.
As long as it can support the extra weight, you can certainly install a pergola on a raised deck.
A pergola can be placed on a wood deck, a concrete deck, or a composite deck that isn’t too high up or built over a body of water. Low-rise decks are the best candidates for pergolas.
Installing a pergola on a raised deck can be tricky, so we recommend hiring a professional contractor to do the job for you.
This ensures that both the deck and the pergola stay stable even after years of use and harsh weather.
Ben has a bachelor’s degree in construction engineering. When not constructing or remodeling X-Ray Rooms, Cardiovascular Labs, and Pharmacies, you can find him at home with wife and two daughters. Outside of family, He loves grilling and barbequing on his Big Green Egg and Blackstone Griddle, as well as working on projects around the house.
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