Back door deck, 4 x 3 m
Sits about 300 mm above the garden, so it meets the back door without a guard. One step runs off the front. This is the size most people search for and the one most merchant lists get wrong, because the joist spacing is set by the board, not by the timber size.
Rectangle · pressure-treated softwood · 4.0 x 3.0 m · 305 mm above ground
What you buy
Worked out from the measurements above by the same take-off the designer uses, with the rule behind every line. No prices: costs only appear once you enter your own supplier rates.
- Decking boards
- 40 at 3.6 m
- Joists
- 11 at 400 mm centres
- Beams
- 3 (12.0 m)
- Posts and footings
- 12 posts, 12 footings
- Concrete
- 36 bags at 20 kg
- Fixings
- 260 clips
- Railing
- None
- Steps
- 2 risers, 3 stringers
- Deck area
- 12.0 sq m
Rows packed into stock lengths, 5% waste included
Spacing from UK timber decking practice (BS 8579)
Carrying the joists down to the posts
Posts at most 1.8 m apart
Post-set concrete for the footings
Counted from the board and joist crossings
No guard needed at this height
Rise about 152 mm per step
Finished deck, measured to the outside of the frame
Open this project and make it yours.
The designer opens with this deck already drawn. Change the size, the height, the material, railing, steps or country, inspect the full take-off and save a summary PDF. The complete pack adds the merchant order file and site documents.
Open in the designerFree, no sign-up. This is a material take-off, not a structural design; spans, footings and guards still need checking against local rules.
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