How to Lay Decking: A Step-by-Step Guide 

If you think you have some basic carpentry skills, you should be able to construct a basic decked area. By planning carefully and making sure to buy good quality building materials and tools, building and learning how to lay decking is something you could do over a weekend. 

If your garden has some uneven land, a raised decking area is a great way of utilising this space. This guide will show you the steps to build decking, whether it is elevated timber decking or on a flat surface.

Shopping list for DIY decking

Before you start installing decking, you need to make sure you have the right tools and materials. Below is a list of everything you need to complete the job. You might already have some of these tools at home. If not, they are a good investment in anticipation of your next DIY project. 

• Cordless screwdriver
• Mitre saw or handsaw
• Spirit level
• Hammer
• Tape measure
• String
• Pegs
• Pencil
• Goggles
• Gloves
• Decking boards
• Decking bearers or tanalised timber (100mm x 50mm)
• Decking screws
• Exterior nails
• Landscaping fabric/weed membrane
• Pea shingle or sand
• Ready-mixed concrete 

Types of decking

• Timber decking: Considered to be the more traditional method, timber can be used for a variety of projects including garden decking and boardwalks. It offers a natural look and many manufacturers now sell sustainable and recyclable decking styles. But before you buy timber decking, it’s important to know about the different options and which one works best for you. 

• Hardwood: From golden tones to rich mahogany, hardwood timber is created from slow-growing trees including oak and ash. Because these trees take a long time to grow, hardwood is the most expensive timber on the market.
  
  Its durability is an attractive selling point - if properly maintained and looked after, hardwood decking has an estimated lifespan of 50 years. It is also rotting-resistant, and fire-resistant, and its natural appearance does not fade. 
  
• Softwood: The easier timber decking to install. Softwood timber is sold at a cheaper price compared to its hardwood counterpart and is more eco-friendly. It is made from fast-growing trees such as pine and spruce. Using pressure-treated softwood means your decking will have a significant lifespan. Even if the softwood is not treated, the lifespan is still an estimated 15 years. 
  
• Composite decking: A sustainable and low-maintenance alternative to timber, composite decking is made from a mix of plastic and wood. It’s anti-slip, resistant to rot and has high durability. Composite deck boards can either be partially or fully enclosed and, unlike traditional timber, has an outer capping that acts as a protection layer.
  
  The lifespan of composite decking is predicted to be between 25-30 years. The boards also don’t need to be varnished, stained or painted, can absorb minimal water and will not fade or crack in direct sunlight. 

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How to lay composite decking vs timber decking

Fitting composite decking is also easy to build compared to its timber counterpart. Instead of drilling boards together, you can use fasteners which are screwed directly onto the joist for a smoother finish. You would still need a timber framework to support it. Before you start to fit composite decking, it’s advised to lay out the decking boards for 72 hours for them to become climatised. 

Follow these 4 easy steps on how to lay decking.

Step 1 - Preparing your area for decking

Make a basic drawing of the area where you want to create the decking. Figure out whether the surface is flat enough for you to lay it straight down or whether you need to build a raised framework underneath. This guide will show you how to make a raised decking, a floating decking and a flat decking.

Then prepare the area where you are building your decking by removing all grass and weeds. If you are laying the decking straight on the ground you need to make sure this surface is flat. Use your spirit level or a piece of timber. 

You then lay down landscaping fabric to cover the area where the decking will go. This is a weed suppressant and will ensure weeds do not grow wild underneath the decking boards and ruin your look. Cover the fabric with a layer of pea shingle or sand.

Step 2 - Building the decking framework

Whether you are making a raised decking or your decking can go flat on your current surface, you need a decking structure to support it. 

How to lay decking on soil or grass

If you are laying it directly on the ground, cut suitable timber to the required length (we suggest 100mm x 50mm tanalised timber). Screw it together with exterior wood screws as this will create a decking base for your deck boards.

You can also lay decking directly at ground level using concrete slabs and a weed-proof membrane. Laying a weed-proof membrane will stop any weeds or grass from growing and the weight of the decking means that the membrane does not need to be pegged down. 

It is still important to lay the decking on a level surface. Make sure to remove any debris or weeds and use a spirit level to check for accuracy. You also want to dig about 50mm and the soil needs to be compact enough to support the decking.

Then, you need to lay rows of concrete slabs for extra stability that will work as a solid base for putting up the decking. Make sure that all corners and the centre are supported with concrete. This will help to spread the weight and prevent sinking.     

How to lay raised decking

To build raised decking, you need to screw the frame into blocks of timber, which you previously inserted into the ground using pre-mixed concrete. These wooden posts need to be at the corners of your decking and depending on the size of the decked area, also at regular 1-metre intervals in between.

The easiest way to get this right is to mark out where the posts should go using string and pegs to measure out the angles needed. Then dig holes for all posts needed and insert the wooden posts using pre-mixed concrete. 

Fill the holes and wait for the concrete to set, making sure all posts are level. After this is completed, screw the framework to the outside of the corner posts and the joist to the posts inside the outer framework. One deck joist per 400mm is what you should aim for.

Screw the timber joists for decking in place using exterior joist screws. Screw in place to both the exterior frame and the post inserted into the ground. If you want to give some extra strength to the decking frame, you can screw support decking beams into some of the posts along the length of your decking. These decking beams should be screwed into the posts immediately below the actual frame (supporting the decking frame/ deck joists).

How to lay a floating deck

You can also have a raised but floating decking. Instead of inserting pillars into the ground, using ready-mixed concrete, you would support the joists and framework with legs cut to the desired decking height. 

These are then screwed onto the inside of the frame in each corner and at 1-metre intervals on the inside joists to add support. Then all the wooden legs should be placed on top of a concrete slab, to provide a level base and enable the spreading of the load evenly.

Step 3 - Lay decking boards

Before laying the decking boards, screw the facing to the side of the framework you have created. It is easier to do this before you start screwing in the actual decking boards. This also helps create a stable decking framework. Make sure the facing or sideboards are flush with the top using a spirit level. Facing is not needed if your decking is placed straight onto the surface.

You are now ready to start cutting and screwing in the decking boards on your timber decking base. Measure out the desired length of your decking boards (flush with the framework or with an overhang depending on your design) and cut using a mitre saw or handsaw.

Fix the decking boards across the joists using two screws per deck joist. The decking gap (space between two adjacent decking boards) should be around 5mm to allow movement. Wood expands and shrinks, so if it’s laid too tight, the decking boards will creak as they press up against each other. 

Repeat this until the decking is finished. The boards need to join halfway across a joist for both boards to be fixed securely. Also, remember to stagger the joins to create a professional effect.

If your decking is elevated, you might need to fix more skirting along the sides of the decking, adding to the initial facing you have already fixed. You can use leftover decking boards for this or buy lattice panels for a more ornate effect.

Step 4 - Looking after your decking 

Timber decking

After you have finished laying your timber decking you might need to treat it with a preserver, to extend the life of the wood. You should also consider varnishing the decking with specialist varnish or stain. These come in a variety of colours.

You should probably treat your timber decking every other year to make it last longer. A decked area can be cleaned free of dirt and algae with the use of a pressure washer.

Composite decking

Luckily, composite decking requires little maintenance to keep its appearance. A simple sweep once or twice a week, when you are out in the garden, should do the trick. But if there are any spillages, particularly of anything oily, it is a good idea to clean the affected area as soon as possible with a neutral soap or detergent.

Be sure not to use anything with harsh chemicals or bleach. This can cause permanent damage to the colour of composite decking. If you decide to use a pressure washer, keep it at a distance of approximately six inches to avoid any damage to the decking boards.

Your One-Stop-Shop For Decking

Building Materials Nationwide offers a wide range of timber decking, composite decking and aggregates through our website to help you with your next construction project from start to finish. Whether you are planning on laying decking, or have plans for a much larger task, our knowledgeable trade experts can help you every step of the way.

If you are in the building industry, you can sign up for a trade account which gives you full access to our product ranges and to your own dedicated account manager. Sign up for a trade account on our website today.