How to build a basic, ground-level deck
Step-by-step advice on laying a simple deck
A simple deck at ground level is a straightforward project – a perfect starting point if you're new to carpentry.
Before you start laying, check out our guide to planning your decking project. This covers everything from decking structures to board designs, and offers an essential introduction.
Our example is of decking that is:
- Laid on flat, soft and level ground
- Laid on the ground floor, not raised
- Not joined to a building
- Without any extra touches like a balustrade or decking lights
- Designed with the boards in a horizontal pattern
If you plan to lay decking that's raised, adjacent to a building or wall, or would like to add a balustrade, head over to our article on laying a raised deck for more information.
Ready to start with your project? Let's go...
- We recommend undertaking any decking project with the help and assistance of a friend.
- Always wear protective safety gear when necessary.
- If securing your decking with footings, make sure there are no cables or pipes underneath where you want to dig. Rent a cable avoidance tool (CAT) to conduct these checks and if found, we suggest reconsidering your decking plans. Or consider installing a hinged trap door in your decking to allow future access to the area.
- Don't burn the off-cuts of pre-treated timber decking as the smoke and ash produced is toxic. Dispose of them as you would ordinary household waste.
The following list of tools and materials includes everything you will need to lay a basic, ground-level deck. Some items are needed for multiple stages in the process, but are only listed once, so be sure to check the steps for further detail.
You might need:
To prepare the site
- Tape measure
- Builder’s line or string and pins
- Club hammer - to drive in the pins
- Edger - also known as a half moon lawn edger or edging iron
- Spirit level - we recommend one at least 450mm in length
- Quick-drying concrete - if making concrete pads
- Brick trowel - to make the concrete pads
- Damp-proof course - to sit on the concrete pads
- Weed control fabric and pegs - to prevent weed growth, but still allow rainwater to reach the water table
To lay sub-frame and cut deck boards
- Decking joists
- Coach screws - 8 or 10mm x length required dependent on what you're securing together
- Coach bolts - 8 or 10mm x length required dependent on thickness of joists
- Combi drill
- Socket set - for the coach bolts and screws
- Panel saw - for a small project or cutting a few very thick pieces of timber, if necessary. Finer-toothed saws leave a neater finish, but take longer to cut with.
- Jigsaw - for making fiddly cuts in timber, if necessary
- Mitre saw - for a large project
- Circular saw - for cutting lots of thick timber, if necessary
- Combination square
- Workbench - if necessary
- Decking end grain protector
- Sandpaper or sander
- Paint brush - to apply the end grain protector
To lay timber deck boards
- Timber decking boards
- Decking screws - we recommend choosing screws that are at least 2.5 times longer than the surface they'll be secured to (the deck boards). And if laying Grassedeck boards, opt for green-coated decking screws to minimise the appearance of the screw heads.
- Twist and flat wood drill bits - to countersink the holes
To lay solid composite deck boards
- Solid composite deck boards - includes start clips and fasteners when purchased online.
- Start clips and hidden fasteners set - only needed as separate purchase if solid composite deck boards are bought in-store.
- Solid composite decking screws
- HSS 3.5mm diameter drill bit
- Protective gloves - for mixing the cement, if required
- Rigger gloves - for handling the boards
- Safety goggles
- Dust mask - look for ones that are suitable for cutting timber
- Ear plugs - when using power tools. Check they work with other safety wear. For example, ear defenders worn over goggles may create a gap, which will let the sound in, so we recommend ear plugs.
- Knee pads
- Decorator gloves - for applying the end grain protector
Before you build the deck, the site needs to be properly prepped.
Measure out the site according to your plan and hammer a peg into each of the four corners.
Run a builder's line from each of the four pegs. This will help you visualise the site.
Clear away any plants, rocks or weeds.
Use an edger to cut into the lawn for a straight cut, and then use a spade to remove the turf.
Use a straightedge (a deck board is perfect for this) with a spirit level on top to check that the whole area is level, and level out any slight unevenness in the ground.
Choose what surface your decking is going to be laid on. There are two options when building on soft ground:
- add concrete pads for extra stability
- or lay straight onto the ground for a simple project
We recommend adding concrete pads as they're not only great for stabilising your deck; they'll ensure your decking lasts longer.
If laying straight onto the ground, jump to Step 3b.
If you’re adding concrete pads
It's key that the concrete pads are positioned in the exact places and that they're all square for the deck joists. For help on this, head to the 'How to square a site' section of our How to build a raised deck article for more advice.
Work out where exactly the pads are required and dig holes roughly 150mm square and 150mm deep at intervals of 1.2m around the deck.
Fill the holes with a quick-drying, ready-to-use concrete to just above ground level. Use a spirit level and straight edge to check that the pads are level with each other, and if not, use a brick trowel to level off the highest points while the concrete is still semi-dry.
When the concrete has hardened off (is completely dry), cover the whole area with weed control fabric (making cut-outs for the concrete pads) and a layer of gravel (40 to 50mm in depth).
Cut and lay squares of damp-proof course to sit between the concrete and the deck joists.
If you’re laying straight onto the ground
Cover the area in a layer of weed control fabric and then 40mm to 50mm of gravel.
Both timber and solid composite deck boards are cut in the same way. We recommend the following products based on the scale of your project.
Lots of cuts: Use a mitre saw (also known as a chop saw). The diameter of the saw's blade determines how wide and thick the cutting material can be. When cutting solid composite boards, we recommend a 254 to 305mm saw blade with 40 teeth or less for the best results.
A few cuts: Use a panel saw.
Fiddly cuts: Use a jigsaw. They're ideal if there's a shape to cut and work well cutting notches and curves in deck boards around obstacles such as posts.
Deep cuts (the timber is thicker than the cutting depth of the mitre saw): Use a panel saw if only making a few cuts, or a circular saw if making lots of cuts.
When cutting Walksure or Grassedeck boards, check that the decorative surface is facing up when you’re cutting them. Don’t worry about the surface lifting - it’s glued down with several continuous lines of glue, so the risk of this lifting is minimal.
Measure and mark the deck board at the desired length.
Use a combination square to mark an accurate line across the deck board. Measure twice before cutting.
Step 2: If using a mitre saw
Position the saw on a sturdy, flat surface (such as a workbench) and clamp it into place.
Set the saw’s angle for the cut required. Unlock or release the saw so that the deck board can be placed against the saw's back rest and clamped into place.
When cutting long boards, ensure the board is adequately positioned and safely held in place so the timber does not drop or get ‘thrown’ by the blade.
Slowly lower the blade and cut the board.
Step 2: If using a panel saw
Clamp the deck board in a workbench and saw.
If cutting a wide or thick piece of timber, clamp a straight-edge along the marked line to provide a straight, accurate cut all the way through the timber.
Step 2: If using a jigsaw
Clamp the deck board, face side up, in a workbench and slowly cut along the line.
Don't go too fast when using a jigsaw or the cut might not be as straight as you want it.
Apply a protective treatment to any cut or recessed timber - be it deck boards, joists or posts - before assembling.
This is applicable to all timber, including Walksure and Grassedeck boards. There's no need to sand or treat solid composite deck boards
Don’t cut down a tree - build your deck around it by including a bit more sub-structure to frame the trunk. Block off the area around the tree by positioning joist off-cuts between the inner joists, secured either end with two coach screws. Then cut and fix the deck boards to fit around the tree. Remember to leave enough space for the tree trunk to thicken and for it to sway in the wind. And consider or research the species as some trees can by very fast growing.
The following instructions show you how to assemble a sub-frame. These steps are necessary for laying both timber and solid composite deck boards.
Even a small deck will be very heavy, so do build it on site and remember when measuring and cutting the outer joists, that the timbers will overlap at the corners.
Before you commit yourself to the build, it’s a good idea to do a dry run of the decking first as you don't want to finish the last row with a thin slither of deck board.
Lay out the joist frame and position the deck boards on top, creating the necessary deck board expansion gaps.
Timber deck boards require a 5 to 8mm expansion gap along the length of the deck boards and a 3mm gap along the ends of the deck boards.
Solid composite deck boards require a 6mm expansion gap along the length of the deck boards and a 3mm gap along the ends of the deck boards.
A gauge screw makes an ideal spacer or use off-cuts of wood. And check that all gaps created are the same for a uniformed finish.
If the deck boards on the end row overhang the joist frame, consider increasing or reducing the expansion gaps of timber deck boards by the recommended amount. This isn't possible for solid composite deck boards as they have one standard size of expansion gap. Alternatively, shorten or increase the outer frame so that your final decking row will finish flush to the edge of the joist frame.
Work all this out before you cut and assemble the deck frame or add concrete pads.
Measure your deck frame and cut to size.
Make two pencil marks on each end of the deck frame's two outer joists - these are at right angles to the inner joists. These marks are where the coach screws will go. Make the marks to align with the centre of the adjoining outer joist. This will total eight marks - two in each corner of the outer joist frame.
Use a flat wood bit to drill recesses into each of the eight marks. These should be the depth of the screw's head and wide enough for a ratchet or socket attachment to tighten them. Also known as countersunk holes, these recesses ensure the screw heads will be flush with the joist surface for a neat finish.
Replace your drill bit for one that's thinner than your coach screw's shank. Line up the adjoining outer joists and drill a pilot hole through the centre of the recess, from the outer joist into the adjoining outer joist. A pilot hole provides a guide hole to help direct the screws and prevents the screw from splitting the wood.
With the pilot holes drilled, it's now time to fit the coach screws. Use either a drill driver with socket attachment, or socket and ratchet to tighten the coach screws into place.
You might find it easier to drill and secure a corner at a time.
Once the outer frame is assembled and in position, it's time to secure the inner joists.
Repeat the process to secure two coach screws through the outer frame into each end of all the inner joists.
The spacing of your inner joists is dependent on your chosen decking design. For more on this, head to the 'Which decking design?' section of our planning article.
Top tip: Conceal joists
If you want to minimise the appearance of joists through the spaces between your deck boards, paint the top of them black.
Top tip: Joining joists
If you're extending your deck further than the length of a joist, clamp the joist sections end to end in a workbench.
Place a joist off-cut about 600mm long across the join, and clamp it temporarily to the joists. Secure it with eight coach bolts sunk from the outside of the frame.
When joining lengths of internal joist (which will be hidden by the deck boards), use two 600mm sections of joist off-cut sandwiched either side of the join for a stronger fix.
The following step-by-step instructions show you how to lay all timber deck boards, including Walksure or Grassedeck boards.
Start in one corner of your sub-frame and position the first board across the inner joists, so that the deck board is in the opposite direction to the inner joists. The board should be positioned flush with the frame.
Position any end to end joins between the deck boards halfway across an inner joist so that both boards can be screwed into the joist for extra stability.
Mark a cutting line for the end of the first board and cut it to fit.
Don’t forget to allow for an expansion gap of 3mm in your measurements when the boards are butted up end to end.
You'll now secure your first deck board to the joists.
The deck board has to be secured to every joist it covers over along the sub-frame. Use two decking screws where each board meets a joist.
Mark the screw locations in pencil, ensuring that they're at least 15mm from the end of the board and at least 20mm from the outside edges.
There's no need to create recesses or countersunk holes for the deck screws, as they're designed to create their own recess when screwed down for a flush finish.
We recommend drilling pilot holes for the screws to help prevent the wood from splitting. Select a drill bit for your drill driver that's thinner than the deck screw's shank and drill pilot holes into the pencil marks - being careful to drill through the deck board and not into the joist.
Screw the decking screws into the pilot holes.
If laying grooved deck boards facing upwards, position the screws at the bottom of a groove.
With the first row in place, you can now start the second row - remembering to include the relevant expansion gap between the boards.
Stagger the deck board joins across the deck for greater strength, and arrange them in a regular pattern for an attractive finish.
If using Grassedeck boards, lay them facing the same direction for a uniform shade of green. Or switch them around for a contrasting look.
Use sandpaper or a sander to smooth over any cut ends if necessary.
Once smoothed down, use a paintbrush to apply an end grain preserver to protect the timber from rot and decay.
Once the preserver is dry, protect your decking further by applying decking stain, oil or wood paint. For more on caring for your timber decking, check out our how to guide.
Fitting solid composite decking doesn't require any specialist tools – you can use the same as if you were fitting a timber deck - the fixings just require a different technique. The grooved side edges of solid composite boards accommodate a hidden fastening system, which allows for a smooth finish across the deck floor.
Like timber decking, solid composite boards require expansion gaps. The hidden fastening system creates a uniformed 6mm expansion gap between boards when fitted width to width, and a 3mm gap fitted end to end. And remember that if you’re fitting solid composite decking next to a wall, you’ll need to leave a minimum of 10mm gap there too.
Starting in one corner of your decking area, fit start clips along one edge of the outer joist. Each start clip should be centred on each outer and inner joist.
Secure the clips with screws (these are supplied as part of the start clip) using a long number 1 square drill bit, also supplied in the pack.
Push the grooved long edge of the solid composite deck board into the start clips, checking that the first board is perfectly straight and well secured.
With the first board in place, slide the hidden fastener into the grooved edge of the deck board.
Align the screw hole in the fastener with the centre of the joist and, using the drill bit supplied, screw half way down. Do not fully tighten at this stage.
Continue along the length of the board, semi-fixing at every joist.
Slide the second board into place, making sure the fasteners fit into the groove.
Install the next set of hidden fasteners on the other side of the second board in the same manner as before. Again, do not fully tighten the screws.
Tighten the screws of the fasteners in the first row.
Continue with steps three through to five, tightening down each row after the board that follows is in place.
The fasteners create the required 6mm expansion gap between the deck boards when fitted width to width.
Top tip: Solid composite drilling
When drilling large or deep holes into solid composite decking, periodically lift the drill bit out of each hole and remove the shavings with a gentle blow.
When installing the last board, there are two options. You can install it:
- flush with a fascia board
- or with an overhang over the outer joists (see step 7b)
For a fascia board fixing
Pre-drill pilot holes at an angle through the grooved edge of deck board into the outer joist. They require pilot holes (by 90% of the length of the screw with a HSS 3.5mm diameter drill bit).
Attach the fascia board flush with the deck surface and screw in the 63mm solid composite deck screws.
For an overhang
Pre-drill pilot holes at a 45 degree angle from below the deck surface through the outer joist.
Position the last board into fasteners, overhanging the outer joist. An unsupported solid composite deck board overhang should not exceed 13mm.
Drill pilot holes and secure the board with solid composite deck screws.
Fit a fascia board below the overhanging deck board for more stability and a neat finish if you fancy.
Top tip: Fixing boards end to end
You may need to stagger the boards across your deck, and when the ends of the deck boards meet, they will need to be fastened to a joist with four hidden fasteners (two for each end of the board).
If the joist is 50mm or wider, the join and 3mm expansion gap will be in the middle of the joist, surrounded by four hidden fasteners.
If the joist is less than 50mm, widen the joist with an off-cut joist and fix the hidden fasteners to the joists as shown.