How to lay decking

Inspired by a helpful YouTube guide. This walk-through draws on the popular Wickes video "How to Lay Decking with Wickes", which covers the whole job clearly from sub-frame to finished boards. Good watch before you price up the timber — the section on joist spacing alone is worth a few minutes of anyone's time.

1. Plan the layout and check beneath the surface

Mark out where the deck will sit and think about drainage before you do anything else. Decking should slope very slightly away from the house — around 1 in 80 is enough to let water run clear without being noticeable underfoot.

Check for underground cables, pipes, and drainage runs before digging or driving posts. If you are not sure, call 0800 96 93 35 (Dial Before You Dig) or use a cable detector. This bit is not exciting, but it really matters.

2. Set out the posts or base

Deck posts can go into concrete, be fixed to concrete pads with post bases, or sit on adjustable deck feet if the ground is solid. Post bases keep the timber off the ground and help it last longer. Worth the small extra cost.

Get each post or base level. A long spirit level and some patience here will save you grief when you come to lay the boards and they sit at an odd angle.

3. Build a sturdy sub-frame

The sub-frame is the frame of bearers and joists the boards sit on. Use pressure-treated timber — brown-treated C16 or C24 structural timber is fine for most domestic decks. Do not use untreated softwood outdoors; it rots surprisingly quickly.

Space joists no more than 400 mm apart if boards run perpendicular to them, or closer if they run at 45 degrees (diagonal patterns look great but put more stress on the frame). Screw or bolt everything together rather than nailing if you can — it is easier to adjust and far easier to take apart if you ever need to.

4. Fix the first board carefully

Start against the house wall or the straightest edge. Fix the first board dead square, because everything else follows from it. Use stainless-steel screws — standard steel rusts quickly outdoors and stains the deck a rusty brown colour. Two screws per joist crossing is the right pattern.

Pre-drill pilot holes near the ends of boards to stop the timber splitting. This is especially important with hardwood decking or anything dried out after sitting in a merchant's yard in the sun.

5. Work across the deck with consistent gaps

Leave a gap of around 5 mm between each board for drainage and to allow for any movement in the timber. Use off-cuts of decking board or spacer clips to keep the gaps even as you go.

Timber moves with moisture, so if you are building in summer during dry weather, err slightly wider on the gaps. In wet weather they will close up a little. That said, do not go too wide or the gaps become a trip hazard for heels and small feet.

6. Cut the edge boards neatly to length

Once all the boards are laid, snap a chalk line along the edge and trim everything in one pass with a circular saw. This gives a much cleaner edge than trying to cut each board perfectly before fixing.

A guide batten clamped along the chalk line will help you keep the saw running straight, especially on longer decks. Mind the blade depth — set it just a touch deeper than the board thickness so you are not nicking the joist below.

7. Finish the edges and treat the timber

Fit a fascia board around the perimeter to hide the frame and give a tidy, finished look. Mitre the corners at 45 degrees if you want the edges to look neat rather than just butted together.

Apply a good-quality decking oil or preservative once the build is done, and plan to repeat it annually or when the wood starts to look thirsty. Properly maintained softwood decking will last 15 to 20 years. Neglected decking starts going at the edges within three or four.

When to call a handyman

Call Richard if the ground slopes awkwardly, if you need a raised deck with balustrades, or if the project has grown beyond a weekend's work. Decking looks straightforward on paper but the prep — levels, posts, drainage — takes experience to get right first time.