How to build a pergola
By Tom Drake | 15th January 2024 | 5 min read
A pergola will be a beautiful addition to any garden. It can add shade to a patio space, encourage trailing plants to grow and will beautifully frame sections of your garden. In this guide, we take you through how you can build your own pergola.
Building a pergola steps:
- Dig post holes
- Fit posts
- Secure posts
- Fit support beams
- Mark up rafters
- Fit rafters
1. Dig post holes
The first step to building your pergola is fitting the posts. Before you start, measure out and mark the dimensions of your pergola and where you want your posts to go. If you're building your pergola over an existing patio, you may need to remove paving slabs and the sub base first. Once the area is clear, you can start digging.
Using a narrow shovel, dig a 0.5m deep hole for your posts. To make the job easier, you can use a post hole digger.
If you're building your pergola on a concrete surface, you could use post supports instead of digging post holes.
2. Fit posts
Once you’ve dug all 4 post holes to the correct depth, you can concrete them in. To give your posts a strong base, we recommend using post supports alongside concrete.
Fit your post support to your post and place it in the hole. Use a spirit level to check it’s level. Once you’ve got your post correctly lined up and level, use some pieces of wood to create temporary supports that can hold the post in place.
3. Secure posts
Postcrete is ready mixed and sets quickly, making it the ideal choice for securing your pergola posts.
First, backfill the hole with stones to give the post some extra stability. Partially fill the hole with clean water, then add enough Postcrete to cover the water. Use a piece of wood to remove any air pockets and level the Postcrete. For more help with Postcrete, check the instructions on the packaging.
Check again that your post is level and adjust your supports if required. You can then repeat the process for the other three corners and give each post 30 minutes to set.
4. Fit support beams
The support beams are the two beams either end of your pergola that the rafters sit on. First, cut these support beams to the correct length. You want them to overhang your posts by an equal amount on both sides.
Next up, you'll need to hammer in a nail on your posts for the support beam to sit on while you secure it. Measuring from the top of the post, mark the width of the support beam. You can then hammer in a nail at this marker on both ends.
You can now sit your support beam on top of the nails and use clamps at both ends to hold it in place. If your support beams are particularly heavy, ask for help when lifting. Use a spirit level to check the beam is level and make sure that the overhang is equal on both sides.
You can now mark where the centre of the post is on your support beam and drill two equally spaced pilot holes. Then, use coach bolts to secure the beam to the post.
5. Mark up rafters
Rafters are the beams which run perpendicular to your support beam. They should overhang the support beam by the same amount on both sides.
Lay your rafters out and align them all at one end. Make sure they’re all the same length and cut down any that are too long.
Measure and mark up the point where the rafter will sit on the support beam. Do this at both ends. You can then drill pilot holes on these markers to make securing the rafters easier once they're sat on the support beam.
6. Fit rafters
With your rafters marked up it’s time to fit them. First, cut a piece of wood to use as a spacer. This will allow you to keep the gaps between your rafters uniform across the pergola.
Before you start fitting your rafters, measure the width of one rafter and your spacer. With this information, you can mark up where you're going to fit your rafters to ensure equal spacing at both ends.
You can now use woodscrews to secure each rafter using the pilot holes you previously drilled. Use your spacer to ensure the distance between each rafter is the same and if your rafters are heavy, make sure you ask for help lifting them onto the support beams.
Complete these steps for the remaining rafters until you're left with a beautiful pergola.
Now you’ve finished your pergola, you may want to use paint or a wood stain to protect it from the elements. We also have a great selection of outdoor lighting and furniture which will help you complete the look of your new pergola.
