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Blog - How To Build A Deck
16 September 2022
Some might think that building a deck can be complicated and often a little confusing to get your head around, so we have created a short guide on how to build the perfect deck. We’ve based our ‘How To’ on a fairly level, open ground area. You may well be planning your deck over an existing concreted/slabbed area, or somewhere with a heavy slope which would require a more specific design and build. Should this be the case, please contact our team for information and guides. On top of FORT’s extensive knowledge and advice, we hold great stocks of both Timber & Composite decking options, which we will discuss in this guide.
Planning
The planning of a deck is the most crucial starting point, we recommend making drawings of your desired decking area, noting down all measurements. To ensure the correct amount of space is used it is vital to gather your measurements. Grab a tape measure and idealize how large and where you’d like your deck to sit within your garden area. Once you have all the measurements noted down you can then calculate the total area that the decking will sit on, having these measurements will help you do determine how many boards are needed. Now that you know your project's ground space, you can start to make calculations based on the boards you will use. Both our stocked Softwood Decking & Trex Composite Decking boards are available in either 3.66 & 4.88m lengths, consider which direction you would like your boards to face. Bear in mind if you are working with a dimension of 4.8x2metres it would be much more cost-efficient to use up the full boards length rather than cutting them to fit a smaller space, such as the 2 metres.
To calculate how many boards you will need, follow this simple method...
We’re working with an area of 5 metres, which equivalates to 5,000milimetres. A typical decking board is 150mm wide, so we will divide the length of 5,000mm by 150mm giving us a figure of – 33.33, suggesting we would need 33 boards to fit the length. If you chose to work with 4.8metre boards it would be wise to add an extra board to be cut and used to fill space.
To sum up…
This will help you build your dream deck and to note all your ideas down on a piece of paper. Add measurements for a better understanding of where exactly you want your deck to sit within your garden area. Contemplate having your deck in an arewherech the sun shines.
Preparing The Ground
Before commencing a decking project, it is vital to prepare the ground for the timber sub-frame to sit on. This means levelling, protecting, and ensuring safety is met. Start by removing any loose stones, weeds, or debris to ensure a clean ground. Place pegs on each corner of the area, this will help you visualise the area you are working on. To guarantee that your decking will last as long as possible it is important to keep it level. Use an edger to cut the upper layer of the lawn and then a spade to clear it away, dig at least 50mm of soil to create fresh/even ground. Verify the ground is even by using a leveller on top of a decking board, then check all areas of the ground are even. We always recommend using our Grountex Woven Geo Fabric, a multi-purpose geo fabric used for weed suppression and ground stabilisation. This ensures no weeds will start to grow through the deck boards. Now that you have your ground prepared, it’s time to build the timber sub-frame!
Building The Sub Frame
Ensuring you have all the necessary materials to build a strong and long-lasting sub-frame is the first step to a successful build. At FORT, we hold fantastic stocks of timber posts, carcassing and all the accessories that you may need. Start by installing your posts making sure that they are 1.5m apart. As they will be in the ground for many years to come we recommend using a quality timber product, such as our Incised, UC4 Treated Posts. A more recent option is using a composite post, which FORT can supply. Composite products consist of stronger properties and can indeed last a lot longer than traditional timber. We recommend starting off with a gap of 250mm followed by 400mm for the following joists, this ensures an even load is made for weight management. On each post, we recommend adding a Postsaver Post-Sleeve, a heat shrinkable sleeve lined with a meltable & bituminous liner. This ensures air and watertight barriers around the ground-line section of the post. Once your posts are protected, you’ll need to secure them into the ground using our stocked Postfix Cement. Constructing the outer frame is the next step, making sure the Timber Joists are securely fitted using Timberdrive screws. When securing the joists we suggest using timber-timber Joist Hangers, which are height adjustable. If you are working with a deck that is 1metre above ground we recommend using bearers, they ensure more weight can be taken for a stronger build. We’ve based our ‘How To’ guide on a fairly level & open ground area. You may well be planning on building your deck over an existing concreted/slabbed area, or somewhere with a heavy slope. That will require some more specific design. The steps to consider are, on existing patio areas, making sure that the deck sits clear from any existing walls and that water can drain away easily.
To start off, build the outer frame using your 4”x2” C16, UC3 Treated Boards along with these Timberdrive Screws, screw together & tighten each corner as you go. Before installing the timber joists measure diagonally to ensure you have kept a straight line. Now that your sub-frame is built you commence the installation of the Pressure Treated Joists.
Timber Treatment & Care
When building a timber decking or even the sub-frame which sits below the boards, it’s important to consider the treatment level & aftercare. Preservative-treated timber can perform excellently for long periods of time, the key to long-life service is design and the most important element is airflow. Keeping timber enclosed in outdoor areas can cause a build-up of moisture and that results in increased insect attack, rot and fungal decay. Allowing the structure to have as much airflow as possible will allow the timber to breathe, meaning less chance of the above. Ensuring you keep a 5mm gap between the boards is important, Trex Universal Clips ensure a gap is kept when installing, to keep added pressure from damaging the structure once the boards expand or shrink.
Protective Joist Tape
Before installing either the composite or timber boards we always recommend adding a layer of protection to the timber, for it to last longer and to have added protection. Using our Trex Protect Adhesive Joist Tape, start laying this tape down on all tops of the boards ensuring no timber is exposed. Now your timber is protected from moisture ingress, which can cause the joists to rot & the chance of the deck screws loosening. This adds years of durability to your sub-frame ensuring a long-lasting deck.
Adding The Boards
Now that your sub-frame is built, and the added protection has been placed it is time to start installing the boards. We will be discussing two different types of boards, those being; Treated Dual Purpose Softwood Decking & Trex Composite Decking Boards. Trex offers a Hidden Fixing System which ensures a ‘Screwless’ finish, meaning no direct screw is fitted to the board. With Trex, we commence the installation using a Square Edge board to create your picture frame, screwing them down using the Trex Coloured Wood Screws or their Pro Plug System. Once the outer frame is created we start to lay the boards down one by one, adding in the Trex Universal Clips which ensure correct gapping & a secure fitment. If a butt-joint is required then it is still recommended to keep a 5mm gap between the boards, both timber & composite.
Here at FORT Builders’ Merchant, we hold fantastic stocks of landscaping materials. Being a major stockist of Trex Composite Decking within the southern area of England, we have the colours and variations ready to take away, on the same day. We recently announced our all-new show deck located in Unit B across from the main FORT HQ, customers can now view the various designs and colours available on site as well as seeing the different ways Trex can be fitted. As well as composite decking, we also have large stocks of traditional Treated Timber Decking boards. With our extensive knowledge in the treatment of wood, you can rest assured that our timber is of great quality. For more information on our UC4 Treated & Incised timber, follow this blog.
Contact our friendly sales team now on 01488 505 800, alternatively, you can place orders via our website for either delivery or collection.