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How to build a pergola

How to build a pergola

Sebastian, self-taught DIY-er, Exeter

Guide written by:

Sebastian, self-taught DIY-er, Exeter

246 guides

In this guide you'll find plans to help you build your own freestanding wooden pergola. Regardless of your DIY skills, we'll take you through each step from choosing the right timber for the structure all the way to anchoring the pergola post bases to concrete, read on to find out how to build a pergola.
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In this guide, we'll set out simple steps to follow to help you build your own pergola. The aim of this tutorial is to make the process as straightforward as possible bearing in mind that there is a huge variety of different pergolas available. In fact, pergolas come in all sorts of sizes with construction ranging from basic to complex and styles varying from traditional to contemporary.

Build a DIY 2x2m pergola

These steps will allow you to build a wooden pergola measuring 2 metres in length and 2.1 metres in height.

Building a custom-made pergola

If the dimensions set out here do not match your needs – in terms of length or width – you can alter them slightly. Reducing the length of the structure shouldn't pose any issues. However, making the pergola longer will be more problematic as the timber structure does have its limits.

The overall length of the joists shouldn't be any greater than 60 times their thickness.

In this example, the beams measure 32 mm (3.2 cm) in thickness so their total unsupported length mustn't exceed 192 cm (since 3.2 x 60 = 192). The total unsupported length of the beams is 172 cm since 14 cm of the beam rests on the posts on each side. If you need to make the structure longer than these recommendations, you will either need to:

  • add some struts (<1 m);
  • add an extra post to better distribute the weight (>1 m).

If you don't follow this basic rule, you may end up with structural weaknesses as the joists start to buckle under their own weight over time.

Materials and consumables

Buying wood for a pergola

To build this pergola, you will need:

  • 4 x posts (14 x 14 x 200 cm)
  • 2 x beams (3.2 x 175 x 200 cm) - A1
  • 2 x beams (3.2 x 17.5 x 193.6 cm) - A2
  • 4 x joists (3.2 cm x 17.5 cm x 193.6 cm) - all of which will have rabbets cut into the ends
  • 2 x crosspieces (50 x 50 mm x 172 cm)

You can choose between heat-treated planed timber and rough sawn timber which you will have to process yourself. If the timber is already planed you won't have to plane it yourself. If you get rough sawn timber, you'll have to plane it or at the very least sand it down using a belt sander (taking care to work with the wood grain). Don't forget to break the edges as you sand.

Choose the straightest timbers possible. Structural (or carcassing) timber often comes in lengths of 4 metres and offers the best value for money if you are able to transport it.
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Hardware

All hardware must be made of stainless steel. Choose countersunk screws with Torx drives to secure your beams and crosspieces. You'll need:

  • 16 x (8 x 60mm) screws - C
  • 16 x (8 x 120 mm) screws - D

The lag bolts that will be used to fit the beams should feature a hex head and a Torx drive for secure tightening. You'll need:

  • 16 (10 x 100mm) lag bolts - E

The posts will also be secured to the pergola post base brackets using lag bolts:

  • 16 x (8 x 20mm) lag bolts.

The post bases will be anchored to the ground using:

  • 16 x (8 x 60mm) through bolts - F

The post bases feature a square base measuring 13 cm on each side and 10 cm in height.
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Wood screws

Cutting your timbers to size

Measure the beams, posts, joists and crosspieces (A, A1, A2, A3, B) and cut them to match the dimensions stated above.

Assembling the beams and posts

  1. Mark the width and depth of the rabbets in the tops of your posts (A) and cut using a circular saw and hand saw.
  2. Mark the width and depth of the rabbets in the ends of your joists (A3) and cut.
To make your cuts, start with the circular saw and finish off with the hand saw.
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Circular saws

Mark out measurements on the roof structure

Mark your measurements on all the pieces of timber that will make up the roof of the pergola.

Assemble and secure the components of the roof

  1. Fasten the beams together ensuring they sit flush with each other. Make sure to pre-drill holes in them and to drill countersinks where the screws will go.
  2. Position the 50x50mm crosspieces on the inside of the beams (A1) 14 cm from each end. Secure the crosspieces and don't forget to pre-drill 15mm deep holes using a drill bit that more or less matches the size of the screw head. These timbers should be screwed (C) into place so that they sit flush with the bottom edge of the beams.
  3. Place the joists over the beams so they are sitting on the crosspieces at intervals of 40 cm (starting 40 cm from each end). Secure the joists to the beams using screws (D).

Securing the metal connectors and brackets

If you don't want your screw heads to be visible along the beams, you can use metal brackets and connectors as set out below. Otherwise, you can use screw caps or wood filler to cover the holes.

Insert the posts into the roof structure

  1. Lift the roof structure and slot the posts one by one into place (you will need to work with someone for this step).
  2. Use a flat wood drill bit to drill holes that are wide enough for a socket head to fit in to tighten your bolts.
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Wood drill bits

Secure the posts to the beams

  1. Start tightening using a cordless screwdriver fitted with a Torx bit and finish off using a ratchet. Repeat the process for all four posts.

You can place bolt caps over the lag bolts to cover up the heads.
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Screwdriver bits

Mark out the position of your post bases

  1. Mark out two lines 199 cm apart on your concrete slab where the post bases will be installed. The outside edge of the post bases should line up with your marks to make up for the 1 cm difference between the size of the post bases (13 cm) and the posts (14 cm), meaning 0.5 cm on each side.
  2. Mark out your drill holes on the ground.

Check the post base layout is square

Be sure to check that everything is square as you are taking your measurements.

Drill and secure the post bases

  1. Drill a hole using an 8 mm masonry drill bit fitted to a drill on hammer mode.
  2. Insert the through bolts.
  3. Put the post bases in place and insert screws using a ratchet spanner followed by an open ended spanner (or a box spanner if you can't around the bolt with a ratchet).
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Spanners and sockets

  1. Position the pergola onto the post bases making sure to position it so that the posts overhang the post bases by 5 mm on each side. You will need four people for this step.
  2. Secure the post bases to the posts using lagbolts and a ratchet spanner.

If you are only working with one other person, screw a crosspiece between two posts and then one on each side to create enough leverage to lift the structure. Once the pergola is standing, you can remove these pieces and fill the holes with wood filler.
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Lag bolts

Hiding the screw heads

Depending on the type of finish you want – and whether or not you have used metal hardware – you have a few options when it comes to finishing the pergola. You can:

  • use screw caps to cover up the screw heads on the beams;
  • apply a wood filler over the holes and sand down once dry;
  • leave the screw heads on show.
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Nut and screw caps

Choosing your finish

Depending on the finish you're after and the wood you have chosen, you can either stain or paint the pergola.
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Exterior wood stain

Required skills

To build your own pergola, you will need to know how to:

  • use a cordless screwdriver;
  • use a circular saw and hand saw;
  • take accurate measurements and use various hand tools.

Time required

  • 1 day

Number of people required

  • 2 people

Tools and equipment

Safety and workwear

Please note: this list is non-exhaustive; be sure to match your PPE to the task at hand.
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Pencils, markers and chalk

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Guide written by:

Sebastian, self-taught DIY-er, Exeter, 246 guides

Sebastian, self-taught DIY-er, Exeter

Redo a roof with wooden beams? Check.Advise Mister everybody in the DIY shop? Check.Redo the bathroom plumbing? Check.Fit together, build the walls, paint a partition, throw my hammer in a rage thinking that it will fix the problem? Check. The DIY motto ? Learning is better than delegating… well, it's also a question about your wallet! The satisfaction? The beer at the end of the job! What do the best have in common? The influence of Gyro Gearloose, Mac Gyver and Carol Smiley depending on your generation, a good dose of curiosity, a average hand-eye coordination and a taste for risks… and if it doesn't work, try again! Advise you? I'll do my best!