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Decking Project Calculator

Enter your deck size, pick a board and colour, and we'll itemise everything the job needs: boards, subframe joists, hidden fixings, fascia trims and membrane — with guide pricing. Then send the whole lot to us as one enquiry.

Your Deck Size

Measure the area you want to deck, in metres. Not sure? Start with a preset.

a · Length (m)

b · Width (m)

Choose Your Board

Both profiles are woodgrain-finished composite in 4.0m lengths. Solid core carries more weight for heavy-traffic and commercial decks.

Choose Your Colour

All five colourways are stocked in both profiles. Free sample packs are available on request.

Finish the Job Properly

Everything below is calculated automatically from your deck size. Switch off anything you already have.

Fascia boards 2.4m matching trims around the deck perimeter to hide the subframe edge. Corner trims 2.4m L-profile trims around the deck perimeter to finish exposed edges and steps. Weed control membrane Heavy-duty 10m² rolls laid under the subframe to stop growth beneath the deck. 5% cutting wastage Recommended Allows for off-cuts and trimming. Most installers order 5% extra board.

How we calculate your estimate

Decking boards — your area ÷ coverage per board (0.56m² hollow, 0.60m² solid), rounded up, plus 5% wastage if selected.
Joists — composite subframe at industry-standard 400mm centres across the deck width, supplied in 2.4m lengths.
T-clip fixings — one clip per board per joist crossing (11 per 4.0m board), supplied in packs of 100 with screws included.
Fascia boards — the full deck perimeter ÷ 2.4m lengths, rounded up.
Corner trims — the full deck perimeter ÷ 2.4m lengths, rounded up, in your chosen board colour.
Membrane — your area ÷ 10m² per roll, rounded up.
Dimension labels — each measurement on the diagram is tagged with a letter (a, b, c, d) so it's clear which input controls which side or cut-out.
L-shaped decks — enter the overall bounding rectangle (a × b), then the size of the corner cut-out (c × d). We calculate area as a × b minus c × d (perimeter is unaffected by a single corner notch, so fascia and corner trim quantities use the same formula as a rectangle).
U-shaped decks — enter the overall bounding rectangle (a × b), then the width and depth of the cut-out notched into the middle of one edge (c × d) — e.g. to wrap around a hot tub or bay window. Area is a × b minus c × d, and the perimeter gains an extra 2 × d for the sides of the notch.

Quantities are a planning guide based on a simple rectangular deck on a standard subframe. Send your basket as an enquiry and we'll check it against your drawings before anything is confirmed.