● Material Selection

For outdoor use, aluminum alloy or galvanized steelkeel are recommended (corrosion-resistant and durable).Wood-plastic composite keel or C4-grade preservative-treated wood keel are also acceptable (economical and practical).

Keel cross-section dimensions should be ≥40mm x 20mm (wood keel)or≥30mm x 30mm (metal keel).

● Spacing Specification

For standard-thickness boards (20-25mm thick), the keel spacing should be≤300mm;for thicker boards (>30mm), the spacing can be increased to 350-400mm, depending on the board manufacturer's instructions.

● Joint Requirements

Leave a 3-5mm expansion joint between boards (5-8mm for outdoor use to accommodate thermal expansion and contraction);leave a 10-15mm buffer joint between boards and walls/obstacles, illed with elastic adhesive strips;if the joint is a right angle, cut a 45°bevel at the four corners to prevent edge damage and cracking.

● Fixing methods

Snap-on fixing(recommended for outdoor use): Use stainless steel snap-ons and screws for fixing. Each board should have at least 2 snap-ons with a spacing of ≤300mm. Screw fixing: Pre-drill holes (the hole diameter should be 1mm larger than the screw diameter to prevent the board from cracking). The screws should be recessed 1~2mm into the board surface.