How to build a raised deck

This list includes everything you will need to build a raised deck. Some of the items are necessary for more than one stage of the project, so do check the steps thoroughly for the tools and equipment needed.

You might need:

To prepare and square the site

• Tape measure
• Builder’s line
• Club hammer - to hammer in the pins
• Edger - also known as a half moon lawn edger or edging iron
• Spade
• Spirit level - we recommend using one over 450mm in length
• Weed control fabric and pegs - to prevent weed growth, but still allow rainwater to drain through
• Gravel
• Builder’s square
• Line level
• Pencil
• Masking tape

To attach a deck to a building

• Stainless steel washers
• Combi drill
• Flat wood drill bit
• Anchor bolts - also known as expansion bolts
• 22 x 100mm (approx.) lengths of timber - for profiles
• 22 x 50 x 1800mm (approx.) length of timber - to make the builder’s square
• 90 x 90mm joist support posts

To build the sub-frame and cut deck boards

• Quick-drying concrete - if required
• Brick trowel - if making concrete pads
• Aerated blocks
• Metal joist hanger
• 50mm nails
• 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 for joining joists together, if needed
• Socket set - for the coach screws
• Panel saw - for a small project or cutting a few very thick pieces of timber, if necessary. Finer-toothed saws offer a neater finish, but take longer to cut with.
• Jigsaw - for making fiddly cuts in timber, if necessary
• Mitre saw - ideal for larger projects
• Circular saw - for cutting lots of thick timber, if necessary
• Workbench
• Sandpaper or sander
• Decking end grain protector
• Paint brush - to apply the end grain protector

To lay deck boards

• 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 bits
• Hand plane or electric planer - if necessary

To add a balustrade

• Quick-release clamps
• Decking posts
• Decking hand rail
• Decking base rail
• Balustrade screen or spindles
• 12mm wooden dowels, cut to 75mm long
• Exterior wood adhesive

To add decking steps

• Paving slabs or block paving - for a secure footing
• Decking step risers
• Decking step timber treads
• Claw hammer
• Coach screws - 6 or 8mm in diameter, with the length dependent on what's being secured
• Reciprocating saw - if necessary
• Chisel

To fit solid composite stair treads

• 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

To add skirting panels

• Lattice panel
• Panel frame - if required
• Wire mesh - if required
• Wire cutters - if required
• 30mm exterior screws
• 20mm wood staples

Protective kit

• Protective gloves - if mixing concrete
• Rigger gloves - for handling the timber
• Safety goggles
• Dust mask - look for ones that are suitable when cutting timber
• Ear plugs - when using power tools. Check they work with other safety wear. As for instance, ear defenders worn over goggles may create a gap which lets the sound in - therefore we recommend ear plugs.
• Knee pads
• Decorator gloves - for applying the end grain protector

Before you build the deck, the site needs to be prepared.

Step 1

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.

Step 2

Clear away all vegetation and rocks within this marked site.

If clearing turf, use an edger to cut into the lawn (it provides a clean, straight cut) and remove the grass with a spade.

Lift the turf in manageable strips, and save it somewhere out of the way (it could be used around your completed deck later on).

Once the site area has been prepared, it's essential to ensure that the sides of the deck are completely square. This is key as the decking will be laid with joist support posts concreted into position. Once these are installed there's no way to move them if they've been put in the wrong place. It will also ensure that your finished deck will look professional. So a bit of extra time spent now on checking the site can help prevent any unwanted problems later on.

The easiest way to achieve this is by using the 3-4-5 triangle method.

The 3-4-5 triangle explained

The 3-4-5 triangle method uses simple geometry to create perfect right angles at the corners. For example, a triangle with sides exactly 3, 4 and 5 metres long - a right angle will form at the corner where the shorter sides meet. Any multiples of 3, 4 and 5 will follow the same pattern.

In our steps below, we will measure 900mm - 1200mm - 1500mm (or you could measure 3ft - 4ft - 5ft).

When the lines are perfectly level and square, mark the position of the string on each crosspiece with a pencil.

Move it to one side and make a small saw cut at the pencil mark. Then tie the line firmly in position at the cut.

This stage involves fixing one joist directly to the wall. You can skip this section if your decking is not being fixed to a wall. The rest of the decking's sub-frame is then aligned with it.

Before starting, check that you won't be blocking off any air bricks or interfering with the damp-proof course (DPC) by attaching the joist.

Step 1

Drill holes at 400mm intervals along the length of the joist being fixed to the wall. Arrange the holes alternately at the top and bottom. Make sure that they are not too close to the edges, or else they will weaken the joist. Check that they don't coincide with the eventual positions of the joist hangers. Measure and plan the position of the holes so that the bolts are secured into the brickwork and not the mortar.

Step 2

Use a flat wood bit to drill recesses in the joist - just deep enough for the nuts and wide enough to allow access for a socket spanner. Make sure you’ve measured and drilled accurately or else the bolts won’t work.

Step 3

Position the joist on the wall using a spirit level to ensure it's level. Make a mark on the wall through each hole.

Remove the joist and select ‘hammer action’ on your drill to drill through the masonry at the marked points. If you've measured correctly in Step 1, drill into the brick - not the mortar.

Step 4

There must be a gap between the timber and the wall to allow rainwater to run down the wall and not pool on the decking.

To create this gap, make a spacer from a few stainless steel washers - they should measure a minimum of 10mm when fitted together.

Place the spacer between the joist and the wall and secure the joist to the wall by inserting expanding masonry bolts into each of the holes. Tighten the bolts with a socket spanner - taking care not to over tighten.

As well as posts at the four corners (corner posts), an elevated deck is also raised on joist support posts. The corner posts don’t sit right in the corners of the sub-frame. They are offset by the width of a post to allow deck posts (which will be needed when attaching railings or balustrades) to be slotted in later. A lot of the work at this stage requires two pairs of hands.

The sub-frame forms the deck’s outer skeleton. Joists run in the opposite direction to the deck boards, so it's important to have settled on a decking design. For more on the different deck board arrangements, head back to our planning article.

And don't worry if there are any existing features (such as trees or posts) that you can't, or don't want to remove - just work around them. Include a bit more sub-structure to frame the obstacle and support the deck boards. Block off the area around it by positioning joist off-cuts between the inner joists (secured either end with two coach screws). Then simply cut and fix the deck boards to fit around it.

If it is a tree, leave enough space for its trunk to thicken and for it to sway in the wind. And be sure to swot up on what species it is, as some can be very fast growing.

It's important to attach balustrades (or railings) to a deck after you've built the sub-frame, but before you lay the deck boards. This is because the decking posts slot in and are fixed to the corner posts, and then the deck boards fit around them.

We're going to run through attaching:

• decking posts
• a handrail
• a base rail
• and wooden spindles (also known as balusters)

But there are plenty of other options. Instead of spindles, opt for a balustrade screen. Finish your decking posts with post caps or ball tops. Add a gate to keep young children and pets safe in one place. Or keep things simple with a complete railings kit. For more on these, and other, decking accessories, check out our decking buyer's guide.

Work out how high you would like the balustrade to be. Cut the wooden spindles down to size if necessary, bearing in mind all safety considerations and Building Regulation requirements.

And don’t forget to allow space beneath the base rail for the deck boards.

When the railings are in place, you're ready to lay your deck boards. Remember that they need to run in the opposite direction to the joists.

For help on cutting deck boards, head to the 'How to cut deck boards' section of our article 'How to build a basic, ground-level deck'.

A basic open stair is all that’s necessary on a low deck, but for higher ones you’ll need handrails. Be sure to check the most up-to-date Building Regulations.

The easiest way to build steps is to buy pre-formed kits that include two stair risers (side panels) and step treads. They're available in three, four and six step options.

Alternatively, build your own with two risers (side panels) and as many separate step treads as you require. We're going to take you through this process for timber deck boards. If looking to lay solid composite decking steps, follow steps one and two below and then jump to the section 'How to fit solid composite stair treads'.

If building your own steps, we suggest:

• A step tread width (the width of the steps) of 900mm - it should not be less than 760mm.
• Stairs wider than 900mm will need to add a central step riser to support the steps and prevent them buckling.
• A step depth (the vertical distance between each step) of between 150 and 180mm if building your own riser. This ensures the steps are a comfortable depth and not so deep that they're an effort to climb, but not so shallow that you trip on them. This is especially important for the bottom step - between the step support pad (the step's foundation) and the first riser.

Step 1

Check that the site for your steps is level and firm - anything uneven or too soft and the steps won't be secure enough and might sink into soft ground.

If no hard landscaping exists there already, consider laying an area of concrete or paving slabs (British Standard Paving is a very strong and durable option). For more on paving options, head to our buyer's guide.

Solid composite deck boards are narrower than timber deck treads, and so two are required to be fitted width to width to provide a comfortably deep stair tread.

Follow steps one and two of 'How to add decking steps' before starting step one below.

Step 1

Install start clips against each riser of the first step.

Step 2

Position the solid composite deck board into the start clips and fix the universal fasteners to the front of the deck boards creating the 6mm expansion gap for the second board.

Step 3

Position the second board and secure with 63mm solid composite deck screws from the top of the second board into the risers.

Repeat this process for each of the steps.

You can add decorative skirting to the exposed space beneath a raised deck by fitting lattice panels.

This can be a practical feature as well, hiding away anything you wish to store beneath your decking and preventing small children and pets from wandering underneath. We're also attaching a wire mesh behind the lattice in our step-by-step advice below, as this helps prevent garden debris and animals from getting under the deck.

If you need access, consider hinging or a different fixing to be able to easily remove the panels.