How to build a pergola

Learn how to build a pergola: our guide is the simplest and the cheapest way to build a pergola – plus we've got all the kit you need

How to build a pergola: Acid drop light by Curiosa & Curiosa
(Image credit: Curiosa & Curiosa)

Want to learn how to build a pergola? While the hot summer days seem a while away, they will come, and building a pergola is an excellent way to create a secluded, shaded area in the garden that will be excellent for al fresco dining or lounging. Follow this practical step-by-step guide to building a pergola and enjoy summer outdoors in comfort and style. Oh, and did we mention that ours is the cheapest way to build a pergola?

For more garden ideas, head to our dedicated page; then check out our ultimate guide on garden design, from planning to costing. 

1. Line up the upright posts of the pergola

How to build a pergola by B&Q

(Image credit: B&Q)

Lay the three upright posts for one side of your pergola on the ground. Cut two lengths of timber to 1.22m and use them to mark the correct distance between the uprights, top and bottom.

2. Line up and mark the pergola rafters

How to build a pergola by B&Q

(Image credit: B&Q)

Lay a rafter in position, jutting 200mm from the edges of the outer posts. Then mark the outline of the post tops on the rafter. As the timbers may not be identical, it's a good idea to number each upright and the rafter in pencil so you can match them up again. Repeat this process with the other side of the pergola.

3. Cut and chisel out the rafter housing

How to build a pergola by B&Q

(Image credit: B&Q)

Cut out the housing with a saw, wood chisel and mallet. Make sure that it's a neat, tight fit.

4. Profile the ends of the rafters and crossbeams

How to build a pergola by B&Q

(Image credit: B&Q)

Profile the ends of the rafters and crossbeams. Then measure 25mm down from the top and 75mm in from the outer edge. Draw a line between these points with a pencil and extend it square down the adjacent faces of the timber. Then saw off the marked wedge - or if you prefer, you could design a decorative profile of your own.

5. Mark out the post holes

How to build a pergola by B&Q

(Image credit: B&Q)

Use the rafters as a guide to help you mark out the post holes. Square their ends with a length of timber and line them up exactly parallel using a 1.32m measure. This'll give you the precise position for the centre of each post hole. Mark these with canes, then remove the timbers and dig the holes to a depth of 450mm.

6. Fit the posts

How to build a pergola by B&Q

(Image credit: B&Q)

Fit the posts into the housings in the rafters. Then drill pilot holes and secure them with two 125mm galvanised nails.

7. Brace the pergola structure

How to build a pergola by B&Q

(Image credit: B&Q)

Use the 1.22m length of wood to space the uprights accurately and a try square to check they're square to the rafter. After that, brace the structure with three lengths of timber.

8. Raise one side of the pergola

How to build a pergola by B&Q

(Image credit: B&Q)

Raise one side of your pergola into the post holes and prop it up with temporary supports. Double-check the posts are vertical and in line with each other and that the rafter is level.

9. Check the levels

How to build a pergola

(Image credit: B&Q)

Raise the other side of the pergola and use a spirit level to make sure both rafters are at the same height. You may have to adjust the depth of the holes when doing this. Finally, concrete the posts in and leave them to set for 48 hours.

10. Fit the pergola cross bars 

how to build a pergola

(Image credit: B&Q)

Start by resting three crossbeams across the rafters at the post positions and nail them into position. Then nail the remaining four crossbeams in place, evenly spaced between the first three.

11. Fit trellis to enclose a pergola

how to build a pergola

(Image credit: B&Q)

Drill pilot holes and nail the first trellis panel into position using 65mm galvanised nails. Remember to leave a gap between the bottom of the trellis and the soil to avoid rot.

how to build a pergola

(Image credit: B&Q)

Finish the job by nailing the final three trellis panels into place.

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