How to Lay Garden Decking

Do You Need Planning Permission for Decking?

Decking generally doesn't require planning permission if: it is no higher than 30cm above ground level and covers less than 50% of the garden area. Raised decking over 30cm, or decking in conservation areas or on listed buildings, may require permission. Check with your local council.

Choosing the Right Decking Material

Pressure-treated softwood (pine): most affordable at £15–£30 per square metre, lasts 10–15 years with maintenance. Hardwood (ipe, balau): premium at £30–£60 per square metre, lasts 25–30 years, very low maintenance. Composite decking: £40–£80 per square metre, virtually maintenance-free, lasts 25+ years. Many consider composite the best value long-term.

Planning Your Deck

Decide on size, height, and orientation. Check for underground pipes and cables before digging (use Dial Before You Dig). Plan the frame direction so boards run perpendicular to the main frame joists. Calculate materials and add 10% for waste.

Step 1 — Prepare the Ground

Clear vegetation and level the ground. For a ground-level deck, lay weed membrane over the area to prevent growth underneath. For a raised deck, prepare concrete post bases or use ground screws (faster and no concrete required).

Step 2 — Build the Frame

Set out and fix the outer frame first, checking for square using the 3-4-5 method. Fix internal joists at 400mm centres for softwood boards or 500mm for composite. All timber must be pressure-treated. Use structural screws or post hangers for all connections.

Step 3 — Fix the Boards

Start at the house wall and work outward. Leave a 5–8mm gap between boards for drainage and expansion. Fix with two screws per board per joist. For hidden fixing systems, use the manufacturer's clips. Keep the first and last boards parallel to the house.

Step 4 — Finish and Maintain

Trim the outer boards flush with a circular saw. Sand any rough edges. Apply a quality decking oil or stain within 2 weeks of installation. Reapply annually or when the wood looks grey and dry. Clean annually with a decking cleaner to prevent algae.