Adding a deck to your garden will provide both a focal point and a place to enjoy in good weather. If carefully constructed, it can also add value to your house. Decking isn’t suitable for shady areas however. When constructing, always use pressure-treated soft wood or hardwood.

What you need:

  1. Pegs and string
  2. Weed-suppressant membrane
  3. Graph paper and pencil
  4. Spade
  5. Decking boards 28mm x 145mm (1 1/8in x 5 1/2in)
  6. Joists ledger & noggins 47mm x 150mm (2in x 6in)
  7. Screws & nails
  8. Fine-toothed saw
  9. Hammer & screwdriver
  10. 6mm (1/4in) spacers

Planning

For your deck to be successful, consider the following:

  • Size: Mark out the proposed area and lay out your furniture to see if is large enough.
  • Location: Choose a position to catch the sun at the times of day when you will want to use the deck. South-westerly facing is usually a good choice but also consider the outlook, whether you will be overlooked, and the prevailing winds. Avoid any drains, underground pipework and cables.
  • Check to see whether planning permission is required.
  • Draw a scale plan and calculate the materials you will need.

Tip: This guide describes the construction of a simple rectangular deck attached to the house, but you could consider wrapping a deck around the corner of your house, around a tree, or siting it away from the house completely.

Step 1: Preparing the site

Clear away vegetation to prepare the site, then mark out the area with pegs and string, making sure it’s square.

Cover the area with a weed-suppressant membrane and grit over top to anchor it in place.

Tip: If you want to place your decking area on sloping land, make sure it is a very gentle slope (no more than 1 in 120).

Step 2: Attaching a ledger to the house

Attach a ledger joist to the wall using spacers for ventilation and drainage. This sets the height for your deck which must be at least 150mm (6in) below the damp proof course (DPC).

Fix securely as the ledger is load-bearing – the best method will vary according to your property’s construction so seek advice.

Step 3: Constructing the framework

Attach a joist at each end of the ledger using angle brackets or galvanised joist hangers and check that they are square.

Fix supporting slabs at the ends of these joists, to hold them level. Lay on 100mm (4in) hardcore and 50mm (2in) sand, then mortar. Allow the mortar to harden while fixing other slabs in place to support other joists every 1.5m (5ft) intervals.

Fit joist hangers (using galvanised nails or screws in every hole) along the ledger at 400mm (16in) intervals. Join to a further joist at the other end to form a supporting beam parallel with the ledger. Check that construction is square and level at all stages.

Nail noggins 400mm (16in) apart between the joists to strengthen and stabilize the framework.

Fit a second joist onto the end joist for further strength and join with coach bolts.

Tip: It is possible to use posts on concrete foundations or fence post bases if you wish to raise the deck.

Step 4: Laying the decking

Decking is the most visible part so take care to line up all fixings and lay straight with equal gaps between boards. You can lay the decking boards diagonally or in other shapes (e.g. herringbone) but this exposes more cut ends with risks of splitting. Always use continuous lengths if possible.

Decking boards with an end grain are best. Lay this way up for reduced warping using two galvanised nails, screws or deck clips at every joist.

Use 6mm (1/4in) spacers or nails on each side of decking board to ensure consistent gaps.

Tip: If any boards need joining, butt together on top of joists.

Step 5: Finishing

Extend the boards over the edges of the side joists and cut straight when all are laid. If you want, use a fine-toothed saw to avoid splitting.

Fix on a facia board to cover the ends.

Tip: If using nails, tap the ends first so they are blunt to avoid splitting the decking. Always drill pilot holes for all screws and nails.