How to Build Simple Decking

Why choose quality decking?

Decking continues to be a popular choice for garden landscapers and opens up a host of possibilities for adding new areas or rooms to a garden, or the ability to revitalise an old paved area. The traditional garden deck is usually sited as an extension from the house, providing a transition between indoors and out, however standalone decks within the garden are becoming increasingly popular, with decking designs even being used for floating pathways and bridges over water features.

When choosing materials to construct a wooden deck it is vital to choose your materials carefully. Invest in high-quality decking boards as budget decking boards will be more prone to warping, splitting and rotting. Our softwood decking boards are crafted from slow-grown Scandinavian Redwood then treated with Tanalith preservative for extra durability. 

Only use UC4 treated wood for building your deck base (UC4 wood materials, such as decking timber and fence posts are treated to make them suitable for prolonged ground contact) - our C24 grade decking joists are kiln dried, treated and strength tested for this purpose. Finally, always use exterior grade screws for a decking project, such as our specialised decking screws and timber landscaping screws.

Decking can be laid in a myriad of formats such as raised or split level, with steps and balustrades, however this introductory guide details how to build a simple deck from timber decking boards at ground level - that is, not a raised deck and not joined to a building. This simple deck could be built over an existing patio, or a firm surface such as earth or a lawn.

Building a deck boils down to five relatively simple, repetitive steps - this is definitely a DIY task for two people:

  1. Prepare site
  2. Build a decking frame
  3. Add internal joists and noggins
  4. Fit decking boards
  5. Finish the edging

Before you start

Planning a simple decked area is fairly straightforward. Draw a plan of your decking (preferably on graph paper) to calculate the quantities of materials that you will need. For help with this, speak to the experts at your local AVS Fencing & Landscaping Supplies branch who have years of experience in planning and installing decking.

Cutting your decking boards and joists to size is a straightforward task with a circular saw, however your local AVS branch may have the facility to do this for you.

The siting of your deck is also worth considering carefully. Avoid the location of your water and electricity supplies, both to avoid inadvertently digging through them, and to ensure that your decking doesn't have to be removed should you need access in the future. If building on open ground or lawn avoid any waterlogged areas, and choose a relatively level spot.

Finally, consider how much sun or shade your decking will receive, and other factors such as privacy or strong winds.

Preparing the decking site

Once you have decided on the perfect spot, mark out your proposed area with pegs and string, using a builder's square to check the corners are square. If on lawn or open ground, dig out any soil or vegetation to a depth of at least 50mm, then cover with weed suppressing membrane and a 50mm layer of gravel to aid drainage. If the ground is soft you may also need to place concrete slabs over the gravel to ensure stability for the decking.

Your decking will need a 'fall' of approximately 1 in 40 (2.5mm drop for every 1m horizontal) to ensure that water drains from the surface. If you're building on top of a patio then this fall should already be built in, but if not then now is the stage to level up any uneven ground with gravel and to build in the fall - use a long piece of wood such as one of your joists to check for an even base.

Building a decking frame

Your decking boards will lay on a sturdy, weatherproof frame constructed from decking joists. To provide support to the entire deck surface the frame has regularly spaced full length internal joists, further strengthened by noggins (small joists fastened at 90 degrees) at intervals between them. This grid of weatherproof joists provides a stable framework for the decking boards to be attached to.

Lay out the four joists for the exterior of the frame in position and check the level (allowing for your slight drop), inserting small risers underneath made from offcuts of treated timber to support and level the joist. Join the outside joists together at each corner using two 150mm external grade screws - drilling a pilot hole first makes this much easier.

Add internal decking joists

Now begin to add the internal joists, these will run at 90 degrees to your decking boards, providing support along their whole length. Starting at the centre, measure 400mm intervals along the outside joist, marking with a pencil. Cut your internal joists to size, then attach a joist hanger at each end with 30mm exterior screws.

Position the internal joist inside the frame, in line with the mark, with the joist hanger at the bottom and the top edge of the joist flush with the frame - use offcuts to support the joist in position while you work. From the outside of the frame, secure the joist at each end with two 100mm exterior screws.

Repeat this process for all of the internal joists, then finally attach all of the joist hangers to the outside frame with 30mm exterior screws.

To give added protection to the frame add decking tape to the top surface of the joists, this will form an additional waterproofing layer especially where water drains between the spaces in your decking boards.

Add your noggins

Mark out 1200mm spaces on the first internal joist, then measure out and cut your noggins from a piece of joist timber. Lay the noggins out between the frame and the first internal joist, and attach at both ends with 100mm exterior screws. Repeat this process for the remaining joists.

TOP TIP - staggering the 1200mm marks on the internal joists makes the noggins easy to fit.

Once the frame is complete, re-check the levels ensuring that the joists are all supported every 500mm if you have used any risers or packing.

Fixing decking boards

Position your first decking board at the edge of the frame, remembering to add a slight overhang if you intend to add fascia boards along the sides. Drill two pilot holes at each end of the board, at least 15mm from the end and 20mm from the outside edge, then fix to the joist with 63mm decking screws. Decking screws are designed to create their own recess so you will not need to countersink them. If your decking board is ridged, always drill into the bottom of a groove.

Repeat the process at every point that the decking board crosses a joist, using two screws at every junction. Wooden decking boards will naturally expand and contract, so it is essential to leave a space of 5-8mm between boards - use a regularly sized spacer at intervals along the board to achieve a consistent gap. It's tempting to use nails or even a nail gun to fix decking boards but we don't recommend this - attaching with screws will provide a much more secure and long lasting fixing.

Repeat until you have covered the whole surface of the deck - hopefully, if you have measured correctly, the surface can be completed with whole decking boards, as cutting a decking board lengthways is a tricky job. 

Finally, fix fascia boards along the outer edges of the frame if required - the best way to do this is with additional decking boards.

Ask the decking experts

For further advice about your decking project don’t hesitate to speak to our experts at your local AVS Fencing & Landscaping Supplies branch - they have years' of experience in planning and laying decking. Our ranges of decking boards and joists are all available to either click and collect from your local AVS Branch or for home delivery within our AVS Branch delivery area

6th Apr 2021 AVS Fencing & Landscaping Supplies