Trellis Calculator — Panel Quantities & Fixings

Use galvanised trellis clips or treated timber battens screwed into the fence posts, not the panels. For face-fixing, drive 4.5 × 50mm screws through the trellis frame into the post — minimum two per side, typically 6–8 screws per 1.83m-wide panel. Leave a 25–50mm gap behind the trellis so climbers can twine through.

Yes — adding trellis on top of an existing fence is common, but the combined fence-plus-trellis height counts as a single structure under permitted development. A boundary adjoining a road must stay below 1m; any other boundary below 2m, or you need planning permission.

Standard UK trellis is 1.83m (6ft) wide and sold in finished heights of roughly 0.3, 0.6, 0.9, 1.2, 1.5 and 1.83m (Jacksons Fencing). You buy the height you want as one panel — you do not stack short panels to build up height. Square and diamond lattice patterns are both common.

Panels run along the length only: divide the wall or fence run by the panel width (1.83m as standard) and round up. For a 3m run that is two panels. Choose the panel height to match the screening you want — taller panels do not need more posts or panels per metre.

Clematis, honeysuckle and jasmine are popular for scent and flower. For evergreen screening use ivy, star jasmine (Trachelospermum) or evergreen clematis. For an edible crop try climbing French beans, runner beans, peas or a grape vine on a warm, sunny aspect.