How to Build a Gazebo on an Existing Deck

By   | Last Updated :   September 13, 2021 | Filed In :   DIY & How To

Want to have a place to relax and get a breath of fresh air? Why not build a gazebo on an existing deck? It’s a great option when you don’t want to ruin your garden or if you don’t have a wide flat section to place a gazebo on.

One of the advantages of building a gazebo on decking is that you won’t have to worry about the gazebo floor. It’s already there, and this saves you a lot of money and hard work. The process is not too complicated, but you’ll have to pay attention not to ruin the deck.

build a gazebo on a deck

Building a gazebo on deck can be a shrewd move. Credit: Shutterstock

In this post, we’ll guide you through how to build a gazebo on a deck, from staking the posts to putting the finishing touches on the roof.

How to build a gazebo on an existing deck

The key to any successful DIY project is good planning. Here’s what you need to know if you want your gazebo project to run smoothly:

You’ll need:

Step 1 – Finding the perfect location

The first thing you need to do is go out on the deck and figure out a convenient space. The deck section should be wide enough to accommodate the gazebo, but that’s not the only factor to consider.

Imagine how the finished structure will look and make sure it doesn’t obstruct the view from your living room window or block any doors.

Another important step is to check with the local authorities and find out whether you need a building permit to build a gazebo. Otherwise, you risk hefty fines or having to tear it all down.

In terms of size, you need to consider what you’re planning to use it for. If all you want is a cool place for you and your partner to relax and have a glass of wine after work, a small gazebo will do.

On the other hand, if you have a large family or like to entertain, you should go with a spacious gazebo, wide enough to fit in patio sofas or deck chairs, and even a table.

Step 2 – Anchoring a gazebo to existing decking

Wherever you live, you have to find a way to anchor the gazebo to the deck so it won’t be blown away by the next storm.

A wooden structure is heavy, but not heavy enough to withstand strong gusts of wind. If it’s not secured, it might be destroyed during a storm, or it might be smashed against the house causing significant damage to your property. The problem is how to do this without destroying the deck. Here are your options:

Bolting the gazebo to the deck

This is by far the safest choice. Once you bolt down the posts to the wooden deck, the whole structure is guaranteed to stay in place even if the area you live in is prone to severe storms.

There’s only one problem. You have to think carefully before starting to build the gazebo, as moving it would be a very hard job, to say nothing of all those holes in your beautiful deck.

Securing the gazebo with metal straps

If you use metal straps to secure the gazebo, moving it or taking it down would be much easier than removing the bolts. Still, this option is less secure if your area sees severe storms every year.

Using containers to anchor the gazebo

This solution is optimal if you don’t want to risk ruining the deck. And it allows you to move the gazebo easily if you decide to push it to a different part of the deck.

You can use concrete containers or even large flower pots, which look nicer. For a regular square gazebo, you need to make sure the containers weigh between 100 and 200 lbs each.

a sturdy white gazebo with a dining set beneath it and festoon lighting around the outside

Heavy planters are an attractive option when it comes to anchoring your gazebo. @thankmyluckystar

You will have to place the containers of your choice in the exact spots the posts will go. Once you put the four posts in place, you can fill the containers with rocks, earth, and also pour concrete to weigh down the containers.

Tip: Fill the top part of the containers with garden soil so you can later plant some flowers or maybe a climbing plant. It will make your gazebo look amazing.

Step 3 – Choosing the shape for a gazebo on a deck

You can always order a gazebo kit, but if it’s your own construction, you can customise it however you want.

You probably don’t want a gazebo that looks exactly like the one your neighbour has, do you?

If you’re not sure of your DIY skills, it might be better to stick with an easy shape—square or rectangular. But if you want your gazebo to stand out, go for a rounded octagonal shape. This type of gazebo requires nine posts, but the process is the same after all. Once you place the first one, the rest should be easy.

Step 4 – Building a gazebo on a deck

Start with placing the posts. For a small square gazebo, 4 posts will do. A rectangular gazebo might require 6, and an octagonal one 9. On the market, you’ll find wooden posts in standard lengths, like 8, 10, or 12 feet.

Choose a height that won’t obscure the view from the upper floor rooms. And don’t forget there’s also a roof that goes on top of the gazebo.

Important: If you use concrete to anchor the posts, allow one day for it to dry.

Once you’ve completed the posts, it’s time to put in the lower joists, which you will have to cut to size from standard length posts.

Building railings and a baluster are optional, but these elements can add some elegance to the gazebo and also strengthen the structure.

Whether or not you add railings and a baluster, don’t forget to put in the upper joists, which will also support the roof.

How to build a round gazebo roof

what is a gazebo

Shaped gazebos add a touch of elegance to your outdoor space. Credit: Shutterstock

Rounded gazebo roofs are very much in style as they give a slightly exotic look to your gazebo. Building a round roof isn’t much more complicated than building a square one.

The upper joists function as support beams for the roof. Your first step is to select resistant wooden beams, like pine, to use as rafters. Go back to the planning board, find the centre of the roof, and calculate the length of the rafters.

Start by working with pairs of opposite rafters. Fix them to the rafters using galvanized screws. Once the rafters are in place, take a plywood sheet and cut it into eight triangular pieces that will go on each side of the octagon. The plywood pieces will make up the base of the roof. Cover the outer layers with tar paper, to keep moisture from seeping in.

You’re nearly there! All that’s left is to cover the roof with shingles. Create a two-layer roof for better insulation and a more impressive look.

Don’t forget to create ridge caps and use them to seal the line where two sides of the roof meet and find something nice to use as a cap for the top of your roof.

Tip: To make sure rainwater won’t damage the structure of the roof, don’t forget to seal the screws with silicone.

Tips on how to build a gazebo on a deck

wooden deck with railings and gazebo

A deck provides an ideal base for a gazebo. Credit: Shutterstock

Here are a few other things you want to consider when building your gazebo on a deck:

Style Matters

Ideally, the gazebo on your deck should match the style of your house. Contrast is good, but only up to a point. For instance, a rounded gazebo will make a nice contrast with the straight lines of the house. Still, you don’t want the gazebo to seem out of place.

You can paint the gazebo posts, or you can use the same type of shingles as those on the roof of your house. This serves to tie in the two structures and make them look like they’re part of a whole.

Check out nearby trees and climbing vines

Consider the trees in your garden and any invasive plants growing near the deck. See that the branches of any nearby tree aren’t too close to the roof of the gazebo, as they might damage it.

Also, if you have climbing vines in your garden, there’s a risk they’ll invade and take over the gazebo. This might look nice. Or not. A vine might also damage any mosquito net that you have fitted.

Rent heavy equipment

There’s no point in buying an electric saw or other power tools for just one project. If you cannot borrow some from a friend, consider renting them.

Closing thoughts

Building a gazebo on a deck makes for a beautiful and functional addition to your property. If the gazebo is right on the deck, you have easy access to it and you can extend your living room space. At least during the warm season.

As for the actual job, there’s not much of a difference between building a gazebo in the garden or on a deck. Actually, it’s easier than building a gazebo on your lawn since you’d have to pour in a concrete floor or build a wooden one from scratch.

Building a gazebo on a deck can be a one-weekend job if you plan in advance and buy all the necessary materials. You can get it done on your own, but having someone to help you will make things much easier, especially when you get to the roof.


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