When you are planning to build a pergola, take time to think about how it will fit in with the rest of your garden. What size, shape, material and size do you want it to be? Do you want it wide enough so that two people can walk through it side by side?

You can construct a pergola simply by using wooden pergola kits or by spacing a number of metal arch kits along a path. If you have good bricklaying skills, pergolas can also be built using brick piers with timber crossbars. In this article, we'll show you how to erect a wooden pergola.

Design

Pergolas should be high enough for adequate head clearance, remembering that climbers will also take up head room: 2.1 m (7 ft) at a minimum. They should be generously wide (about 1.2-2 m or 4-6 1/2 ft) with their posts a minimum of 45 cm (18 in) from the edge of the path. Uprights should be positioned every 2 m (6 1/2 ft). Choose wood that has been pressure-treated with preservative or is naturally durable such as western red cedar.

Materials

• Uprights: 10 cm x 10 cm x 3.2 m, in pairs, the length of your pergola space
• Side beams: 2.5 cm x 15 cm, two - to run the length of your pergola space
• Crossbeams: 2.5 cm x 15 cm, long enough so that there is a 20cm overhang on each side of the upright pairs
• Rafters: 5 cm x 2.5 cm or 5 cm x 5 cm, the same length as the crossbeams
• Trellis panels to fit between uprights (optional)

Method

1. Paint or stain all the wood with two coats before you start building. It's easier to cover every part before you have put them into place.
2. Mark out where you want to place the upright posts using pegs and string. Make sure that pairs of holes line up across the pergola.
3. Dig a hole for each post - this must be deep enough for about a quarter of the post to be underground. Complete the holes in pairs, to ensure they are square with each other.
4. Fill the bottom of the hole with a 15 cm (6 in) base of hardcore, then stand the post in the hole and pack it round with more hardcore to hold it in position.
5. Pour in concrete and tamp down. Finish the mortar about 5 cm (2 in) below soil level.
6. Check that all posts are upright using a spirit level, and then leave to set for a couple of days before fixing the crossbeams and sidebeams. Alternatively, use metal post holders.
7. Make a mark on the front and the reverse side of each upright post 10 cm (4 in) from the top.
8. Take the first crossbeam (this will go across the path) and hold it across the front of the first pair of posts, so that the top of the beam rests on the 10 cm mark you made.
9. Use nails underneath the beams to help support them while you screw them into place. Check it is level using a spirit level before fixing.
10. Secure the second crossbeam on the other side of the first pair of posts in the same way.
11. Repeat with each pair of uprights. You will now have a series of archways.
12. Fix the side beams underneath the crossbeams so that they run the length of the pergola. You could make a notch joint in them so that they fit snugly under the cross beams.
13. The rafters can now be fixed on top of the pergola side beams; these can also be notched to provide a neater finish.
14. Trellis may be optionally secured to the uprights so that they connect each archway, forming a tunnel
15. Check that all post tops are level - you may have to trim them. Apply a coat of wood preservative to any sawn ends.
16. Fill the top of each post hole with soil around. Your pergola is now ready to plant up.