A simple pergola construction can be turned into an arbor by adding trellis panels on three sides. You can place a bench or other seat in this enclosure or you can build an integral bench instead; many pergolas with integral benches are available in kit form. Climbing plants can be tied to the trellis for support, and fragrant types are particularly desirable. Additional trellis panels built onto the side of the arbor ensure that the structure links into the surrounding planting; cover these with climbers as well. Be aware that flimsy do-it-yourself arbors will not last as long as more solid constructions. Some companies sell and install magnificent hardwood structures, but they are expensive. The following instructions are based on an arbor with integral bench in kit form.
Before starting, site the arbor against a backdrop of shrubs and to give views across the garden. To add comfort and privacy, build a bench of smooth, planed lumber across the narrow part of the pergola; this is particularly nice when placed at the end of a covered walkway. Adding side trellis panels for climbers will allow you to tie in adjacent plantings.
hammer or mallet
A constructed Freestanding Wooden Pergola
2 backrest supports, as supplied
2 seat supports, as supplied
planed lumber seat and backrest, as supplied
2 spiked metal post supports
2 treated lumber posts, as supplied
5 trellis panels, as supplied: 2 narrow for sides, 1 large for back, 2 medium for front
Begin fitting the seat by joining 1 backrest support and 1 beam to support the seat together by means of a simple half-lap joint. The angle at which this joint is cut determines the slope of the backrest.
It will ideally be about 18 inches (45 cm) above ground level. Remember that ground level may be higher if you pave beneath the seat at a later date. Screw the two seat supports to the inside of the pergola at the correct height first. Make sure the two supports are level with each other and that the backrest support is flush on the back posts. Screw in.
Evenly spaced slats, as supplied in the kit, are already joined by screws to battens on either side for both the seat and backrest. Screw the backrest to the backrest support, making sure it is even along the top.
Trellis panels can then be fitted into the two sides and onto the back of the pergola to enclose the seat, and at right angles each side. Attach the panels by following the steps outlined in this tutorial. You can also attach ball finials to the top of the posts if you wish.