Installing timber decking is a great way to create a space in your garden which can be used for relaxing and entertaining. Timber decking can either be freestanding or attached to your house, and it really gives you a chance to be creative with design and function. A single level deck is relatively straightforward to plan and build, however something a bit more complicated can include balustrades, railings and steps.
Learning how to lay decking is a great idea if you're a competent DIYer — it's pretty achievable and a low-risk project, and will save you a lot doing it yourself in comparison to hiring in a tradesperson.
This first step is something you will want to take a considerable amount of time on. Deciding on the size, shape and style of your garden deck is very important regardless of what you intend to use it for.
Do you want the deck to be attached to your house or set back in your garden? Where will it receive the most/least amount of sunshine? Do you want it to be on ground level or raised up? Will it be just a flat deck or do you want balustrades? Do you want built in seating? The list is endless!
Knowing exactly what you want and where you want it will help you understand the costs and time scales involved.
Creating a decked area can be quite heavy in its use of materials. For example, a 4.5 x 3.3m deck project took:
48 linear metres of wood
36 deck boards
800 screws
Something worth costing up is how much a similar project would cost for a professional to make against the investment in the required tools for future projects if you don't already own them.
Tool List:
Tape measure
Drill
Jigsaw
Hammer
Nail gun (optional)
Spirit level
Screwdrivers
Battery drill/ screwdriver
Workbench
Gloves
Mitre saw
Materials:
Weed control fabric
Wood for framework
50mm number-8 decking screws
100mm nails or nail gun ‘clips’
Wood preserver
25mm x 50mm wood for stakes
Decking
Slabs
Measuring out the size of your new deck should not only be done on paper. We recommend laying out some string to the exact positioning of where your deck will be. Seeing it on a piece of paper or on your computer is one thing, but seeing it where it will eventually be will really drive home the scale of the project.
Most people find that seeing it in ‘reality’ makes it look much larger than on paper, so being able to see exactly the scale of the deck is very beneficial.
Once you are happy that the size of the deck you want and that it will fit into the space you have, you’re ready to go!
Prepare the ground
Preparing the ground, or ‘oversite’, is vital to the whole integrity of the structure.
If you do not intend on utilising an under deck drainage system (which can be very expensive) then you need to build your deck on an oversite with free draining. The industry standard is a gradient of 1 in 40.
Using grooved wooden boards that run down the slope of the deck will also help with draining. Having them run across the slope means they may collect water and make the surface slippery.
Measure out the site
Measure out the oversite according to your plan and hammer a peg into each of the four corners.
Next, run a builders line from each of the four pegs. Doing this will help you to visualise the site.
Once you have mapped out your site, you are ready to begin!
Clearing away
Be sure to clear away and rocks, weeds and vegetation. Use an edging iron to cut the lawn in a straight line with the required dimensions. Next, use a spade to remove the turf. Doing this also allows you to re-balance your surface if you do not have a natural slope.
Laying straight onto the ground
If you are laying your frame straight onto the ground, simply cover the oversite with a layer of weed control fabric and then a layer of gravel 40-50mm deep.
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Ground level deck
Firstly, you want to measure your deck frame, loosely assemble it to the size you want and then lay it on the oversite.
Once you have done this, we recommend you lay your decking boards down onto the frame to check that the boards will sit flush with the end of the frame. Doing this correctly will ensure that you won’t be left with a slither of a board at one end!
If necessary, you may prefer to extend or reduce the size of your frame to accommodate the decking boards to allow them to sit flush and neat.
Remember, different types of wood will require a different amount of space between each board.
For instance, timber boards will require approximately 5-8mm gap for expansion along the length of the boards and a 3mm gap along the ends.
You could use something like a spacer or piece of metal that is of the similar size of thickness, to measure along and assure a uniform gap between the boards.
To assemble the frame together, make marks with a pencil on the two outer joists – this is where the screws will go. Make sure to align these screws with the centre of the adjoining outer joists.
You will then be left with 8 marks in total – two on each corner.
Next, using a flat wood bit, drill countersunk holes into each of these pencil marks. Make sure these countersunk holes are at the depth of the coach screw’s head but also wide enough so you can use a ratchet or socket attachment so you can tighten them.
Creating countersunk recesses will allow for the screw heads to sit flush with the joist finish. It will also allow you to quickly and easily attach a fascia should you wish.
Swap over your drill bit for one that is thinner than your coach screw’s shank (the section with no thread that starts immediately after the head). Then create pilot holes into the countersunk holes, from the outside, into the adjoining joist post.
You can now assemble the frame. Use a socket attachment on a drill driver or a ratchet to help tighten the coach screws into place. We recommend you drill and secure one corner at a time.
Once the outer frame is assembled and in position, it’s time to secure the inner joists.
Simply repeat the process to secure the two coach screws through the outer frame and into each end off all the inner joists
The spacing of the inner joists will depend on your decking design and size.
To fix your boards to your decking frame, start in one corner and position the first board across the inner joists (so the deck board is in the opposite direction of the inner joists). The board should be flush with the frame.
Be sure to position the end of end joins between the boards halfway across an inner joist. This will mean that both boards can be screwed into the joist for extra stability.
When cutting any boards, make sure to allow for an expansion gap of 3mm for when the boards are laid end to end.
You’re now ready to secure your board into the joists.
Securing the joists
The decking board must be secured to every joist that it covers along the sub-frame. Make sure to use two decking screws where each board meets a joist.
Ensure the screw locations are at least 15mm from the end of the board and at least 20mm from the outside edges.
If your decking boards is grooved, insert the screws into the bottom of the groove to allow the finish to the flush.
Once you have secured the first row into place, you can then continue with the rest, remembering to include the appropriate expansion gap between each board.
Try to stagger the deck board joins across the deck (his will add greater strength) and arrange them in a pattern for an attractive finish.
If necessary, use sandpaper or a sander to smooth over any cut ends.
Once the ends are smooth, apply an end grain preserver to protect the wood from rot.
Your deck is now ready for a finish.
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