How to Build Decking

Even if you decide to hire a professional tradesman for a home improvement project, it doesn’t mean that it’s all smooth sailing. If you have committed to supplying the materials and prepare the work site yourself, you have a responsibility to making the job as easy as possible for the tradesman.

“Utter madness already. The truck’s crane is broken so they have gone back with the wood. Redelivering. I stupidly ordered 9 times too many posts that go into the ground, so they go back.” This is a comment from a homeowner about their recent decking job, which started out as a really stressful situation.

how to build decking

 The homeowner wasn’t sure how much material to order, but wanted to handle the initial stages himself (in an attempt to save money). This meant that there was so much material left over that the tradesmen could build a pot-plant runner (see image below)! Communicating with the tradesman beforehand always helps and can also save you money (or at least stress).

Once the tradesmen started the job and the homeowner had done his part, the decking job got under way smoothly.

how to install decking

Our essential advice on how to build decking

The first job is to decide where you want to place the decking. Decking is great for areas of the lawn which isn’t growing so well, so if you have a sad corner, decking might be the answer.  It’s important to pick a place where the ground is levelled and water won’t collect. If you suspect that water will gather underneath the decking, you need to raise it to increase its life span and protect it from rot.

The next task is to lay out the beams parallel to each other. You can do a dry run on the lawn to see if the size will be enough for your outdoor furniture. If you want a deck just outside your house ensure that you don’t lay it too close to foundation, as the wood will be exposed to damp – leave a 2-inch gap.

build a deck

Create a framework and connect the timber, ensuring it has the right measurements. If the decking will sit on top of an area which you have cleared of grass and weed, place a weed membrane on the ground. Unlike a black bin bag, this will allow rain water to trickle through. The more you protect the wood from exposure to water, the longer it will last.


In the frame, lay out the cross timber so the decking can carry the weight of furniture and folks without bouncing. If the decking is raised, you can support the cross timber with wooden blocks, placed on concrete slabs.

laying decking

When you start laying out the decking, use a screw to create a gap width of around 3-5mm between the joists. As the wood contracts and grows according to the weather, you need those springs. You also need to make sure that rain water can make its way down.

The decking in these photos cost £1500, materials included. The homeowner went for 70% PEFC certified Redwood pine decking, with a 38 x 120mm measurement. The thicker the timber is, the sturdier it gets and means it can handle many garden parties ahead.

deck installation

The pot-plant runner made from the extra timber.

Decking is an advanced job and should only be attempted by someone who is confident tackling DIY projects. If you don’t have the skills, we know a much easier way. Find a carpenter and save yourself from those stressful moments with the spirit level.

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