Add A Pergola

Prepare the site using stringlines to set out a 6 x 2.4m rectangle.

Check the area for square with a builder’s square and take diagonal measurements between corners.

Mark the positions of the footing holes and excavate the holes to the required size then fill with concrete.

INSTALL three 135 x 135mm posts secured to concrete footings on galvanised supports and attach a ledger to the side of the house.

ADD a roof by bolting front and side beams to the posts and ledger.

SECURE rafters set at a 5º angle between the ledger and front beam.

TOP the rafters with six equally spaced battens for lateral stability, set parallel to the front beam.

BRACE the structure with knee braces positioned parallel to the house wall off the corner posts. Footing sizes vary with soil type and wind ratings. In high-wind areas, specific post supports that must be anchored in the concrete footings are needed, so check all requirements with your local building authority.

For an exterior build, it is essential to finish the timber correctly.

SEAL all cut ends, drilled holes, notches and rebates using an APVMA registered timber preservative end sealer.

PRIME all sealed surfaces once they are dry to ensure the treatment area is thoroughly sealed.

To give the pergola structural strength and a solid look, we chose treated pine posts with a large 135 x 135mm section size, but 88 and 112mm square posts are also available.

Before erecting and securing the three posts, secure supports to the bases and brace the posts in position. Establish the finished height and mark it on the post tops.

Cut the housings in the top of the posts to carry the front beam, then seal all cut ends ready for installation.

To finish, apply two coats of semi-gloss exterior acrylic to the posts and all pergola components to provide protection from the elements. We used the Colorbond colour Dune to blend in with the house.

TIP To make finishing quicker and easier, apply at least one coat of paint before building starts.

The post bases had 5mm wide slots cut 110mm deep to accommodate the centre-fix supports, then bolt holes were drilled through the posts to align with the holes in the support plates.

TIP Seal the cut ends with timber preservative.

Step 1. Cut slots

Cut slots for the support plates, 110mm high and 5mm wide with a circular saw, then a handsaw. Centre the support to mark bolt hole locations on both sides of the post.

Drill the holes to 20mm deep with a 25mm spade bit to make recesses for the washers and nuts. Use a twist bit matching the bolt size to drill through from both sides.

Install the supports by tapping the plate into position. Align the holes and secure using stainless steel cuphead bolts, washers and nuts, tightened with a socket wrench.

Brace the pergola by adding knee braces inside the corner posts. Use a mitresaw to cut them with opposing 45º angles on the ends. Position between the front beam and posts, drill 8mm countersunk clearance holes and secure with screws.

Step 1. Set out rafters

Mark the rafter setout on the ledger, aligning the first and last rafter with the ledger ends and locating the rest at 832mm centres.

Position the ledger on the beam, setting it 65mm in from each end, then transfer the setout to the beam with the rafters 60mm from the base.

Mark hole locations at 450mm centres on the ledger, drilling recesses 25mm in diameter and 20mm deep, finishing with a 12mm twist bit.

Flick a level chalkline to show the height, then prop the ledger in position. Use a hammer drill to bore 12mm holes, securing the ledger with Dynabolts.

Brace an end post in position, then cut a 5º bevel on one rafter.

Butt the cut end of the rafter against the ledger so it slopes at 5º past the post, then clamp it to the post and mark the position.

Repeat for the other end post, checking for level using a water level.