If you take a walk around your neighbourhood, you’ll probably notice that most people have square gazebos in their gardens. It’s not surprising, since they’re easier to build than round ones.
The only tricky part is how to build a four-sided gazebo roof. It needs to be symmetrical and also sturdy enough to resist all kinds of weather.
In this post, we’ll take you step by step through all the stages of building a four-sided gazebo roof. You don’t have to be an expert craftsman to pull this project off, having decent DIY skills will do.
So, without further ado, let’s get to work.
How to build a square gazebo roof step by step
If you want to get the job done quickly and avoid frustrating delays caused by unscheduled trips to the store, gather all the materials you’ll need in advance. Also, make sure you have the right tools ready. You can then go on to design the pitched roof, install the upper joists and rafters, build the roof and shingle it.
Note: This plan refers to building a 4 sided roof for a gazebo that has a king post. That’s the post right in the centre of the structure. Its main function is to support the roof.
Materials you’ll need
- 2×4 lumber pieces cut to the desired size
- Plywood sheets or wood boards
- Asphalt shingles or cedar shingles
- Tar paper
Tools you’ll need
Step 1 – Design the pitched roof
This is probably the hardest part. If you mess up the plan, you’ll end up with a lopsided roof or no roof at all.
A four-sided roof is practically a pyramid on top of your gazebo. The base of your pyramid is formed by the upper joists. The top is the point where the hip rafters connect to the king post.
Determine the height of the pyramid and calculate the length of the hip rafters. The rest of the rafters are easier to deal with. You can figure out their length once you’re done installing the main frame of the roof.
Make sure you have enough 2×4 lumber pieces. Don’t worry if you end up with some leftover pieces. You can always use them for another DIY garden project.
Tip: If you have a rectangular gazebo, you can still build a pitched roof, but go over your calculations carefully so that the rafters meet right in the centre. To avoid nasty surprises, it’s better to build a ridged roof over a rectangular gazebo.
Step 2 – Install the upper joists
For a square gazebo, the upper joists are all the same size, and they’re equal in length with the rim (or lower) joists. If you’ve managed to build the lower part of the gazebo, putting up the upper joists is a piece of cake.
The upper joists go on top of the four perimeter posts. Cut the ends of the lumber piece in an L shape so they fit nicely on top of the posts. Use 2 screws for each end for added strength.
Step 3 – Install the hip rafters
The hip rafters are the four lumber pieces that go from each corner of the gazebo to the top. The four hip rafters connect to the king post much like a teepee, and there’s really not much to it.
If your gazebo doesn’t have a king post, no worries. You won’t have to tear the gazebo down to place an extra post in the middle. You can do without one. Instead of connecting the hip rafters to the king post, screw them to a small piece of wood cut from a lumber piece.
However, if you don’t have a king post, it will be easier to build the roof frame on the ground and then lift it on top of the upper joists. You’ll need a couple of friends to help with that.
Step 4 – Install the intermediate rafters
The intermediate rafters are the lumber pieces that create the frame for each side of the roof. You’ll have to put up four rafters that connect the middle of each upper joist to the king post.
After that, you’ll have to place smaller intermediate rafters right in the middle of each section. These smaller rafters connect to the hip rafters rather than the king post.
Once again, since the four sides are equal in size, you only need to take a couple of measurements and then cut all the lumber pieces you need.
Tip: As a precaution, when you cut one of the intermediate rafters, climb up the ladder and make sure it fits nicely. In case there’s been a small error, you risk cutting the lumber wrong and you might have to buy new pieces.
Step 5 – Start building the roof
Up to now, you’ve been dealing with the frame of the roof. The actual roof consists of plywood sheets and shingles.
Using plywood sheets is the most affordable option, and they’re so much easier to cut than wooden boards. However, if you want to use wooden boards, the roof will be more resilient. Be aware that wooden boards are heavy, you need to make sure the structure can bear the weight and you must have a king post for the structure to be solid.
Most people just go with plywood. If you have large plywood sheets you need to cut four triangular pieces that make up the sides of the pyramid. Secure them in place using galvanised screws.
Step 6 – Shingle the roof
This is one of the easiest parts of building a four-sided gazebo roof. It’s also a crucial part because you need to insulate the roof well if you don’t want it to rot by next season.
The most common method to make the roof waterproof is to cover the plywood with tar paper sheets. It’s a small job as you can quickly staple the tar paper to the plywood boards and you’re done.
The final part is laying the asphalt shingles. For a really good job, you should use two layers of shingles. For the lower layer, place the shingles upside down, while for the upper layer, you need to place them with the right side up.
Place rows of shingles starting from the upper joists and work your way up, making sure that the rows overlap at least 1 inch, to help with drainage. Use a utility knife to trim the shingle rows as needed.
Use the leftover shingles to build rim caps that will seal the edges and cover the top of the pyramid.
Tip: You can also use cedar shingles, which not only look better but are also more resilient. It’s a little extra work, plus, they’re more expensive than asphalt shingles.
Learn more: How to Shingle a Gazebo Roof
How to build a 4 sided gazebo roof quickly
If you’re putting up a temporary gazebo and don’t care much about the way it looks, you can cut back on all the work and create a roof from a sheet of heavy-duty outdoor fabric.
You still need to install the rafters, at least the hip ones and those that are placed in the middle of each side.
Just cover the roof frame with the fabric and trim as necessary. The fabric should go at least 2 inches over the upper joists to allow the water to drain faster. Staple the fabric to the lumber pieces and you’re done.
This type of roof is suitable for temporary structures or if you live in an area that doesn’t see heavy rains. If too much water accumulates on top of the roof, the fabric will start sagging. Also, it will wear down quickly and the roof will start leaking.
How to make your gazebo roof water-resistant
Nothing damages the roof of your gazebo faster than water. If the roof frame starts to rot, there’s the risk your roof will start leaking or collapse altogether.
To make the roof water-resistant, you can use a self-sealing membrane to cover the plywood sheets, in which case the tar paper won’t be necessary.
Also, if you’re going to use cedar shingles, you should consider staining them as this makes them water-resistant. At the same time, you want to install a nylon underlay between the plywood sheets and the shingles.
The nylon underlay allows air to circulate between the two layers and the lower part of the shingles will dry faster. Good ventilation also keeps the plywood from rotting and breaking down.
Tip: A minor detail few people think about is that water might seep into the wood around the screws. It’s not much, but if the lumber pieces are constantly wet in that area, it can do a lot of damage. The easiest way to prevent that is to put a bit of silicone over the screws using silicone caulk.
Building a four-sided gazebo roof is easier if you have a king post, but you can manage without one too.
Installing the hip rafters and the intermediary rafters requires some work. But often, the most important step is just getting the measurements right and cutting your lumber to size.
If at any point in the process you begin to falter, think of all the pleasant days you’re going to enjoy with friends and family under the cooling shade of your new gazebo roof. That will make all the measuring and all the sweat worth it, right?