Can My Deck Support a Pergola ( Facts and Contractor Guides)

Last updated on December 5th, 2022

You may have seen people install pergolas in their yards and may be wondering if you could add one to your deck too. So, you might ask, “can my deck support a pergola”?

Well, the short answer is…maybe! We wish we could say it’s a YES or NO situation, but it really isn’t. Factors such as the deck type, the age or condition, the height off the ground, and the weight of the pergola will determine whether you can add the pergola or not. But most likely, if your deck is built to modern standard, it should be able to hold a pergola.

Adding a pergola to your deck is a nice way to spruce up the area while providing shade from the hot sun. In this article, we will look at when and why you should add a pergola to a deck, how to add a pergola to a deck, and what to consider when setting up the structure. Keep reading to find out more!

How much weight can a deck hold?

This depends on several factors, such as the size of the deck, the material, and the age/condition. On average, a deck should be able to hold about 100 pounds per square foot. For areas with building codes and regulations, it’s usually lesser. A deck is required to hold a minimum of 50 pounds per square foot.

Knowing how much your deck can hold is a good idea as it allows you to determine what kind of pergola to build on it. Also, if you live in an area that gets a lot of snowfall, you will be able to ascertain whether the deck can hold both the weight of the pergola and several feet of snow.

Can my deck support a pergola?

Most decks, whether traditional or modern style, can support a pergola. Specifically, most modern decks are designed to hold at least 100 pounds per square foot. Depending on the size, most pergolas can weigh between 150 to 500 pounds. While some heavier pergolas may require additional deck reinforcement, lighter pergolas don’t usually require this.

Can My Wooden Deck Support a Pergola?

Yes, you can anchor a pergola to a wooden deck, but this depends on how well the deck footings are placed. Using the correct base structure (with regard to design) will make your job a lot easier. This doesn’t mean you can’t install the pergola if the deck is already there. It’s just that you will need to do more work in installing the right base parts. Choosing wood support beams that are pressure-treated is highly recommended.

Can My Composite Deck Support a Pergola?

Yes, you can, but you will need a ledger board. The ledger board is what holds the pergola beams in place so you can attach the roof. It’s also important to know the deck’s load capacity and not to go beyond this. Once you determine how much weight the deck can hold per square foot (we recommend at least 100 pounds per square foot), make sure the pergola weight is within this limit.

Can My Rooftop Deck Support a Pergola?

A rooftop deck is no different from any typical deck, so it should be able to bear a pergola. Just make sure each square foot of space on the deck can support at least 100 pounds of weight.

One of the many advantages of installing a pergola on a rooftop deck is that it can be used to showcase the greenery in your home.

Can I put a pergola on a raised deck?

While it’s OK to install a pergola on almost any deck, it’s not advised to do on a raised deck. This is because, unlike ground-level decks, raised decks are elevated and thus held together by support beams. As a result, they have a lower weight-bearing capacity than regular decks at ground level and therefore may not offer adequate support for large pergolas.

However, you may be able to install a small pergola on it. In this case, you should use lightweight wood for the roof.

If you do decide to erect a heavy pergola on raised deck, have a professional inspect the deck and ascertain whether you can proceed with the installation. Don’t attempt to build it on your own.

Can I install a Pergola on a Deck Built Over Water?

This is not recommended. A pergola built over water is, technically, a raised deck. So, unless you’re sure of the deck’s weight endurance, you probably shouldn’t install a pergola on it. The deck can easily collapse under the excessive weight of a heavy pergola, which could be very disastrous.

We recommend seeking expert opinion if you do decide to build a pergola on a Deck built over water.

Why Get a Pergola for Your Deck?

There are several benefits of adding a pergola to your deck. Here are the main ones:

Shade Your Deck

The most common reason people install pergolas over their deck is to protect them from the sun and rain. This is more obvious during the hotter months of summer. With a pergola roof over your head, you can sit outside when the sun is at its hottest and enjoy the cool summer breeze and nature with your loved ones or friends. Also, your outdoor furniture is kept from direct sun exposure, which greatly minimizes fading.

Elevate Your Outdoor Space

Pergolas don’t only shade you from the sun’s hot rays; they also make your property look great. Adding one to your deck is a nice way to transform the area and make it more inviting. You can add beautiful greenery such as hanging vines or flowers to create a peaceful and pleasant extension of your home, perfect for relaxing.

The good thing is that there are so many pergola styles, colors, and materials available, which you can customize to your taste.

Perfect for Entertaining

With a deck pergola, you can create an interesting outdoor living room or space which gives you more options for entertaining. You can host big parties and utilize the extra space provided or you can use it as your outdoor dining space. You can also invite neighbors or friends over to enjoy a few steaks or some tasty burgers together on hot summer evenings or during the cooler months. To make things more interesting, consider adding fairy lights, a sound system, or chandeliers, and you will be amazed at the transformation.

How to add Pergola Deck?

Building a pergola on a deck is not the same as building it directly on the ground. The former is a bit more complex and requires more planning and preparation.

With “ground pergolas,” you have to bury each post in the ground and then add concrete, dirt, or gravel to give it more stability. Whereas, with deck pergolas, you connect wood to wood, which potentially makes the structure less stable. Our recommendation for building such pergolas is to hire a contractor.

You should only build one yourself if you have advanced DIY skills and knowledge about the safety and structural requirements. In this case, getting a pergola kit built to specifications might be better.

What You Need

  • Screwdriver
  • Saw
  • Power drill
  • Hex bit sockets
  • Fasteners
  • Gloves
  • Safety goggles
  • A helping hand

Get the Dimension

Start by measuring the area you want to place the pergola. Depending on whether you’re building an attached or free-standing pergola, you will need at least two or four support posts. For an attached pergola, you will need a support board to hold the horizontal beams. Measure the length of the support board needed. Likewise, measure the places where you will connect to the deck joists. Depending on the pergola type (attached or freestanding), this could be two or four.

Choose Your Pergola Size

Pergolas come in different sizes – 10×10, 10×14, 12×12, 12×14, 16×16, 20×20, and so on. The right size for you will depend on factors such as the available space on your deck, the weight it can handle, the placement of support joists, and what you intend to use the pergola for.

For the pergola material, we highly recommend using pressure-treated wood or cedar, at least for the supports. Besides being strong, these woods are resistant to termite attack or rot.

In addition, choose fasteners that are designed for wood. Consider the weight and thickness of the joists and supports, and make sure the fasteners come with washers. Popular choices include carriage bolts and lag screws.

Installing the Posts

Once you resolve the pergola size and footprint, the next thing is to locate where you want to attach the support posts, which is usually the deck joists. This makes sense since the joists support the deck. The best way to go about this is to have a friend hold the post in place where you want to connect it to the joist. Then, mark the area and cut through it to create the hole where you will fit the post through.

If you’re building an attached pergola, you will need to cut out two holes for the two support posts. But to install free standing pergolas, you will need four posts.

Connect the Posts to the Joists

Now that you have the area marked out and cut, lower the post in place. It’s best to have someone hold the post while you drill holes through the post and joist. The screw size will depend on the pergola size but in most cases, 2½ “x6” lag screws and washers will serve the purpose.

Do this for each support post.

Attach the Crossbeams.

Once you’ve connected the pergola posts to the deck joists, you can now attach the horizontal crossbeams. The beams help to support the rafters and need to be affixed to the pergola posts. To do this, create an indent into the top of the posts that is about the width and thickness of the beam. Then set the beam into the indent, drill, and screw it into place.

Attach to the House

This step is applicable if you’re attaching the pergola to your home. Mount the ledger board to the side of the house where you want to connect the pergola. This should be done using the wall studs. The board should be the same width as the pergola.

Next, attach joist hangers to the board. They should be the same width as your rafters. Once this is done, insert the rafters into the hangers so that it overhangs the horizontal beams between the two support posts. You can use 9×1½ lags screws or suitable hurricane ties and common nails to connect the rafters to the supports.

The above method can slightly change if you want to attach a pergola to a house with gutters. It is recommended you consult a contractor or an expert in pergola installation.

Connect the Rafters

The next thing is to connect the rafters to overhang the beams. But you have to keep them centered. The best way to do this is to lay each rafter in place before you fix them down. Begin with the rafter at the center, then lay others on either side till they overhang the beams. This will take a lot of time and effort but is crucial because it can make or mar the overall look of the pergola.

Once you’re done setting the rafters, you’re almost through with the installation. You may want to paint the pergola the same color as the deck so they blend well together.

How Much Does It Cost to Build a Pergola on a Deck?

This depends on several factors such as the size, style, materials used, where it’s being installed, and whether or not you hire a professional. Generally, the cost can be anywhere from $500 to $7,000 or even more. So, we can approximate the average pergola cost to about $3,600.

Installing the pergola yourself will reduce cost since you will only pay for the materials, not labor. You can save about $500-$1,000, or even more if the structure is more elaborate. So, if you have the time, building the pergola yourself is the best way to cut down on cost. But make sure you know the safety and structural requirements before undertaking the project.

You can make the work easier by purchasing a pergola kit built to your specifications.

What Kind of Deck Can Support a Pergola?

When it comes to what kind of deck to install a pergola, the best options we’ve found so far are concrete decks and wooden pergola decks.

Wooden Deck

Most traditional wood decks are built at the same level as the back door of the house. This allows you to attach a pergola to the roof and existing deck.

It helps to know that wooden decks built low to the ground usually provide the most support. This also applies to other types of decks. In addition, low decks don’t require much work initially before installation.

You can replace the corner beams of the wood deck with the pergola posts. When this is not possible, you will need to cut out holes in the deck boards and sink the wood support beams or posts into the foundation. This is best handled by a contractor.

Concrete Deck

Just like a low wooden deck, a concrete deck provides ample support for a pergola. The deck could be made out of concrete or stones, or it might feature a wooden board (deck) over a stone or cement slab.

To install a pergola on the concrete deck or pavers, you can cut through to sink the posts. Or you can extend the posts outside the perimeter of the deck or patio; that way, you won’t need to cut into the concrete.

What Kind of Deck Cannot Support a Pergola?

Any deck built over water or soft ground can’t support a pergola. The structure will be highly unstable and could collapse at any time. It would take a contractor a lot of work and time to sink a permanent foundation into the water, which would cost a lot of money. Not to mention that floods and bad weather can wear down the supports before you know it, which might eventually lead to the total collapse of the structure.

The same thing applies to decks built several feet above ground level. Pergolas built on such decks are more vulnerable to the wind and extreme weather.

If you decide to add a pergola to a high elevated deck, make sure one side is attached to the house. This way, the building can bear some of its weight. The pergola posts would need to be connected to the joists under the deck and sunk into the same foundation; else, they would be highly unstable. For extremely tall elevated decks, this may still not be safe, not to mention that it would be costly to build.

What to Consider Before Building a Pergola on Your Deck

Deck Type

As earlier indicated, there are different types of decks – wood, composite, concrete, rooftop, raised deck, etc. Depending on the one you have, you may find the installation process easy or tricky. Generally, it’s easiest to install pergolas on decks at ground level, whether it’s a wooden deck or composite. On the other hand, raised decks are trickier to build on since they don’t provide much support.

Deck Condition

Another thing you should consider when building a pergola on a deck is the age and condition of the deck. A deck made out of wood and one made out of composite will not break down at the same time. So, if you have an older deck, you may want to rebuild it before adding a pergola. Otherwise, you run the risk of the entire structure collapsing and causing more damage than you could have imagined.

Attached or Freestanding Pergola

Most deck pergolas usually have one side attached to the house. If you don’t like this option, you can opt for a freestanding pergola. The main factors to consider here are the size and shape of your deck as well as the placement. How you plan to use the pergola will also influence your decision.

The main advantage of an attached pergola is that it’s easy to integrate into your home’s architecture. But with a standalone pergola, you have more freedom with size and shape.

Pergola Weight

The pergola weight is another thing to consider when building a pergola on a deck. You don’t want to build something heavier than what the deck can support. The pergola weight will depend on the material. For example, a pergola that is made out of reinforced steel would weigh a lot more than one made out of wood or composite. Before choosing a particular pergola material, make sure you know how much weight your deck can hold.

Additional Tips For Pergola Installation on Deck

Opt for pressure-treated wood

A deck pergola has greater exposure to the wind than one installed at ground level. So, you need wood or material that can guarantee structural wood. It’s highly recommended to use pressure-treated wood or cedar, even if it’s only for the pergola posts. This is important because the weight of the whole structure rests on the posts, so you need wood that can withstand that much pressure.

Besides providing stability, pressure-treated wood is resistant to rot and bad weather, which makes it ideal for long-term use.

Consider adding railings or crossbars

If you have doubts about the stability of the pergola, you can add railings between the posts to provide additional support. Railings or crossbars help to strengthen the whole structure, making it safer for everyone.

Choose a lightweight roof

One way to make your pergola more stable is to use a lightweight roof. Using a roof that is too heavy will not only stress the posts but the deck as well, leading to a shorter lifespan of the whole structure. The best way to avoid this is not to go top-heavy with the roof.

Opt for light wood lattice or fabric panels

Instead of using a canvas cover or heavy wood to create additional shade, consider using light wood lattice or fabric panels. This is another way to reduce the weight of the pergola. You can also add light decors (such as hanging vines) to the roof or walls to spruce up the area.

Choose the best style but don’t compromise on quality

It’s always a good idea to choose a pergola style that blends well with your aesthetics. Notwithstanding, you should be able to do this without compromising on practicality. This means using the best available material for the job.

So, if you live in a place that gets a lot of rainfall or humidity, you want to stay away from wood that absorbs water or is prone to termite attack. Likewise, if you’re using metal supports, you want to use something that is treated against rust.

Connect the support posts to the deck joists

Ensure you attach the pergola posts to the joists under the deck, not the floorboards. This is similar to locating the stud in a wall when you want to hang a heavy object.

Not attaching the posts to the deck joists could cause the floorboards to pull away, resulting in a total collapse of the entire pergola.

Check your local municipality for any special permissions

While most areas don’t have any restrictions on building pergolas and other outdoor structures, some do. To be on the safe side, it’s recommended you check your HOA or local council to see if there are any special requirements for building a pergola before you start the project. Failure to do this could result in a heavy fine from your local government down the road. In some cases, the pergola can be taken down altogether.

 

FAQS: Can My Deck Support A Pergola?

How Tall Should a Pergola Be on a Deck?

The standard height of pergolas is around 8 to 12 feet. It could be taller depending on the size of the pergola, where you plan to build it, and the available outdoor living space. If you plan to build a pergola taller than 12 feet, make sure to check your local municipality for any restrictions or special permits.

Do I Need a Permit to Build A Pergola?

This depends on your local area. Permit requirements vary by city and state. In most cases, you won’t need a permit to build a pergola, especially if it’s small or a standalone unit. However, it’s best to check with your local municipality or HOA before you start the project.

Does a pergola need to be anchored?

Yes, it’s highly recommended you anchor your pergola to the ground, primarily for safety and stability. Pergolas that are not properly anchored can be moved in high winds or warp over time. The most secure option is to set the pergola posts in concrete.

Can My Concrete Slab Patio Support a Pergola?

If the concrete slab is at least 4-inches thick, you can install a pergola on it. To do this, you will need anchor brackets to bolt the posts to the concrete. Make sure there are at least 12-inches of space between the posts and the outside edge.

Can my Pavers Support a Pergola?

Pavers, by themselves, do not usually provide enough support for a pergola, especially in high wind conditions. If you wish to install a pergola on pavers, then it’s recommended to use concrete footings or post fittings. You can also concrete the base if you don’t want to drill or remove the existing pavers. Leg weights can also be used to anchor down each beam, but this should be used as a temporary solution.

Conclusion

That’s all we will cover in this post “can my deck support a pergola.” A pergola is a perfect addition to a deck, especially if you want something a bit extra or sophisticated. Most modern decks will hold at least 100 pounds per square foot, while the average pergola weight is approximately 350 pounds.

Low decks usually provide the best support for a pergola, while stilts or raised decks are less stable and difficult to build on. So, if you plan to add to a deck a few feet above ground level, have a contractor evaluate its structural integrity, and prepare a plan if possible.

Let us know if you have any more questions about building pergolas on decks. In the meantime, tell us what type of pergola appeals to you the most for a deck

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