What You Need to Build Decking: Tools and Materials Checklist (UK)
Most garden decking is built with a mitre saw, a drill and an impact driver, plus a spade and a spirit level for the supports. Little needs hiring unless you are concreting posts in hard ground. A 4 × 3 m deck takes 31 deck boards of 144 mm by 3 m, 11 joists at 400 mm centres, about 462 decking screws and 13 m² of weed membrane. The checklist is below, and the decking materials calculator works out your own size.
The tool checklist, stage by stage
1. Set out and prepare the ground
| Tool | What it is for | Own or hire |
|---|---|---|
| Tape measure and builder's square | Setting out the deck square, and checking the diagonals | Own |
| String line and pegs | Marking the outline and the height | Own |
| Spade and a rake | Clearing and levelling the ground | Own |
| Stanley knife | Cutting the weed membrane to fit | Own |
| Post hole spade, or an auger | Digging holes for posts or pads | Own, or hire an auger |
2. Build the frame
| Tool | What it is for | Own or hire |
|---|---|---|
| Mitre saw | Square, clean cuts on joists and boards | Own or borrow |
| Circular saw or a hand saw | Longer cuts and notches | Own |
| Combination square and a pencil | Marking cuts and joist positions | Own |
| Spirit level (1.2 m) | Levelling the frame, with a slight fall for water | Own |
| Combi drill and an impact driver | Pilot holes, frame screws and coach screws | Own |
| Clamps | Holding joists while you fix them | Own |
3. Lay the boards
| Tool | What it is for | Own or hire |
|---|---|---|
| Spacers | Even gaps between boards for drainage | Own |
| Chalk line | Straight screw lines and trimming the ends | Own |
| Countersink bit | Neat screw heads that do not split the board ends | Own |
| Jigsaw | Cutting round posts and corners | Own |
4. Finish and protect
| Tool | What it is for | Own or hire |
|---|---|---|
| End-grain preserver and a brush | Treating every cut end of treated timber | Own |
| Decking oil and a pad or brush | Protecting the boards once they have weathered | Own |
Safety kit
- Safety glasses for every cut, and ear defenders for the mitre saw.
- Gloves when you handle treated timber, and a dust mask when you cut it.
- Keep the saw's guard working, and clamp short pieces rather than holding them.
- Check for buried services before you dig, using the free LSBUD service.
- A deck higher than 30 cm above the ground needs planning permission in many cases, so check before you build.
Materials for other deck sizes
144 mm boards with 5 mm gaps, joists at 400 mm centres, 10% extra. The tool list stays the same, but the screws climb with the area: the 6 × 4 m deck takes 864, so buy them in tubs rather than small boxes.
| Deck | Deck boards | Joists | Decking screws | Weed membrane |
|---|---|---|---|---|
| 3 × 3 m | 24 boards of 3 m | 9 | 378 | 10 m² |
| 4 × 3 m | 31 boards of 3 m | 11 | 462 | 13 m² |
| 5 × 4 m | 50 boards of 3 m | 14 | 756 | 22 m² |
| 6 × 4 m | 60 boards of 3 m | 16 | 864 | 26 m² |
See the decking materials list for how each number is worked out, how many joists do I need, the common mistakes when building decking and the decking, fencing and sheds planner. Estimates only: follow the timber supplier's guidance on spans.
Frequently asked questions
What tools do I need to build decking?
A tape measure and builder's square, string line and pegs, a spade, a spirit level, a mitre saw, a circular saw or hand saw, a combi drill, an impact driver, clamps, spacers, a chalk line and a jigsaw.
Do I need an impact driver for decking?
It is not essential, but it drives 462 decking screws far more easily than a drill and is less likely to strip the heads.
How many decking boards for a 4 x 3 m deck?
31 boards of 144 mm by 3 m, with 5 mm gaps and 10% extra, on 11 joists at 400 mm centres.
Do I need planning permission for decking?
Often not, but under permitted development in England decking more than 30 cm above the ground, or covering more than half the garden, needs planning permission. Check with your council, and the rules differ in Wales, Scotland and Northern Ireland.
More guides
Tools & materials for this project
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Estimates only. Quantities depend on your materials, site and supplier. Confirm important numbers before you order, and check the Building Regulations and any planning rules for anything structural or close to a boundary.
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