A pergola or gazebo can be a fantastic addition to any garden, creating structure and separating the garden into distinct areas with unique purposes.
Pergolas can be adorned with privacy screens and roofed with temporary or permanent waterproof surfaces to make then usable in all weather.
This DIY pergola guide will save you a heap of money compared to getting one installed by experts or even buying most kits.
Of course it involves more work but for the handy amongst us it will be an enjoyable experience. If you aren’t keen on doing all this hard work but still want to save some money then check out our pick of the best pergola kits.
This is a no nonsense guide to building a freestanding pergola from scratch with minimal tools.
I will walk you through at each stage what you need and anything you need to watch out for along the way.
I will walk you through how to build a 3.1m x 3.6m pergola as seen in the image above however the general process will work for the dimensions you choose as not as the design is not too different.
Tools you will need
- Hand saw
- Electric drill / screwdriver (10mm and 6mm drill bit)
- Trenching spade
- Post hole diggers (optional but recommended to save your back)
- Tape measure
- Spirit level
- Step ladder
- Someone to help out (probably best if they are not a tool)
- Wheelbarrow
- Construction pencil
- Adjustable spanner
- Paint brush
- Hammer
Materials
- 4 x 20kg post mix
- 4 x 3m treated timber posts (150x150mm)
- 9 x 4.3m treated timber joists (100 x 200mm)
- 8 x Galvanised coach bolts
- 30 x 80mm screws
- Marking spray
- Sand paper
- Pins / nails (to hold joists in place temporarily)
All materials can usually be ordered online or from a local builder merchants
Step by step guide to building a freestanding pergola
Step 1: Measure out the area and dig the post holes
When you have decided how big you want your pergola to be measure out a square with the corners where you want the corners of the post to be.
Mark out where the post will go (a 150 x 150mm square) then draw another square around this but 50mm wider. This will be the area you will dig out to allow room for the post and the post mix.
Using a post hole spade dig out each square to 0.45 or 0.6m depth (the deeper you go the more securely it will be held).
Using the trenching spade to loosen the earth then post hole diggers to remove the earth is the fastest and easiest method we have found to dig deep holes.
Important: Cables and utilities can run under any area, make sure you survey the area for signs and use safe digging practices to avoid any dangerous and expensive accidents.
Step 2: Cut and set the posts
Materials: 3m x 150x150mm treated timber posts, 4x 25kg of post mix
First, cut each post to the length you want it, the barer beams will be 200mm lower than the top of the post and the top joists will be 200mm higher than the top of the posts. For this design we have gone with 3m posts which will make to top of the posts 2.4m above ground.
Mark out and cut a 100x200mm notch in the top of each post as seen in the image. This is where the barer joists will sit.
Place each post in to the hole pour in the post mix and enough water to completely saturate the post mix. Use a stick to make sure the post mix completely surrounds the post.
Use a spirit level to vertically and horizontally align each post.
Perfectly aligned posts may not need support but if necessary use bits of wood to stabilise the post until it is set.
Step 3: Cut and fit the baring joists
Once the posts are properly set as per the post mix manufacturers instructions you can cut and fit the barer joists. Don’t cut these before had in case your posts are not exactly the right distance apart (small variations will not be noticeable).
We have opted for a 300mm overhang and taper on the end of each barer joist.
First, set up the barer joist on the notches you cut from the legs, move the barer joist until the end is 30cm from the edge of the post, mark the 30cm point.
On the other leg mark the 30cm point (where the barer meets the the outer edge of the post, mark 30cm from this point.
Next cut the joist the length.
To get the right taper (the slope on the end of the joist) simply measure and mark the middle of the end of the joist (100mm down for our 200mm wide joists). Draw a line from this point to the 30cm point. Cut down this line and sand the rough edges.
Finally lift the barer joists back onto the legs and position them. Mark where you want the coach bolts to go and use the 100mm drill to make two evenly spaced holes. Inset the coach bolts and tighten using the adjustable spanner.
Step 4: Cut and fit the top joists
Using the same cutting process in step 3 measure, cut and taper the top joists to fit your pergola. Thankfully you can just measure one and repeat the same cuts on each of them.
To get the top joist spacings correct begin by lining up the two end joists so the corer of the top joists lines up with the outer edge of the barer joist and the outer edge of the posts.
Fix the joist in place with a nail or pin (don’t hit this in too far as it will need to come out soon.
Measure the inner gap between the two outer top joists. Divide this by 5 (or however may top joist you opt for) and mark a line at that point then another 50mm to the left of that point.
Line each joist up with the outer edge line you have just made and fix them in place with a pin or nail.
Make any adjustments until it looks how to you want it
To securely fix the top joists you will nee d 2 screws for each end of each joist. Get the 6mm drill bit and attach some duct tape or electrical tape 1cm from the end of the drill bit so there is just 1 cm showing.
Drill a 45 degree diagonal hole in to each side of each joist where you will need to insert a screw to attach the top joist to the barer joist.
In the holes you have just drilled screw in a 80mm screw to attach the top joists to the barer joists.
This method fixes the joists more securely and hides the heads of the screws for a nice finish. Its tempting to skip the shallow pilot holes but that little bit of extra effort will make for a much nicer result.
How to build a pergola
I hope you have found this guide on how to build a pergola useful, We frequently bring out new guides and recommendations to help you make the most of your garden.
