How to make a pergola
You will need:
- Timber posts 100x100mm (4x4in) by 3m (10ft)
- Main and cross beams, approx 150x50mm (6x 2in) diameter and length to fit
- Galvanised nails sized 75mm (3in)
- Exterior wood glue
- Wood preservative
Time to complete job: 1-1.5 days
Approximate budget: £120 - £150
A pergola can be remarkably versatile in the garden. It can frame a view or cover a walkway linking different garden areas. It can provide shade in a sunny corner with climbers growing up the poles or it can support hanging baskets.
Pergolas vary widely - from long and narrow to rectangular - and can be designed to suit your garden style. Kits are widely available but if standard sizes don't suit you, here's how to make your own.
Pergolas work particularly well in cottage or traditional garden settings, or in oriental-themed gardens.
Step 1: Designing your pergola
The location of your pergola will affect the construction materials used. A rustic pole construction usually looks better at a distance, whereas one of planed timber is more fitting adjacent to a house.
If you use softwood, either buy pressure-treated or apply preservative yourself. Always apply extra preservative on cut ends.
The uprights should be at least 75x75mm (3x3in) wide and about 3m (10ft) long as they will need sinking 0.5 m (2ft) into the ground for adequate foundations. If you are placing the pergola on a firm concrete foundation, you could use metal fence bases which bolt through the concrete.
Your pergola can, if adjacent to a house, omit poles down the house side. The cross beams are then fixed directly to the wall using joist hangers, as illustrated.
If fixing on top of decking, you can either set the posts in the ground around the edge, or position through holes cut through the decking next to a joist. Use two offset coachbolts to attach the base of the posts to a sturdy joist for stability.
Your individual design may, if large, need additional supporting posts - every 2.5m (8ft) or so is about right.
Step 2: Fixing supporting posts
Dig foundation holes 450-600mm (1.5-2.5ft) deep and fix supporting posts with hardcore and cement checking they are vertical and in line with the direction of the pergola.
If you are fixing the pergola above a concrete floor, then you can buy metal post holders that bolt into the concrete, that the posts can fit into.
Step 3: Fixing the main beams
Main beams should now be attached to the top of the posts to form the side supports on which the crossbeams will sit.
This can be achieved either by fitting coach bolts straight through both pieces of timber - staggered as illustrated - or by cutting a rebate out of the top of the posts before fixing in place so that the joist rests on a ledge.
Secure with 75mm (3in) galvanised nails. Or you can could hold the timbers together with coach bolts.
Step 4: Fixing the crossbeams
Crossbeams can be fitted 600mm (2ft) apart along the length of the main beams, overhanging by about 300mm (1ft).
Carefully measure where they touch the main beams and cut out rebates so they slot over the main beams, then fix with galvanised nails and exterior wood glue.
If you wish to give an oriental look to your pergola, trim the bottom corners off the ends of each crossbeam and main beam - remember to treat all cut surfaces with wood preservative.
If you are fitting over decking it is a good idea to stain the pergola the same as the deck colour.