How to Install Decking
When it comes to laying decking, there are a few things you need to know before getting started. Measure twice, cut once, as they say — preparation is key to getting a DIY project like a decking completed to your satisfaction.
The best thing about installing a deck is that if you’re new to carpentry this is an ideal first project. Installing decking by yourself is doable, though you’re likely to want a friend to come and help out.
Whilst laying a deck may seem complicated to the complete beginner, rest assured that decking is well within the means of anyone willing to learn how to go about it!
For this guide, we’re going to assume that you’ve already planned and designed your decking, chosen your decking boards, and calculated your material requirements. Each of these topics would require an entire guide themselves, so we’re focusing only on laying the decking here.
Top tip: If you have chosen wooden decking boards, you should let them acclimatise for at least a week before beginning your decking project. This allows the boards to get used to the climate in your garden as opposed to the warehouse they were stored, which can vary with moisture and temperature greatly.
Working safely when laying decking
Installing decking is a relatively simple job, but there are some safety measures to remind ourselves of before we begin.
- Use eye protection when pressure washing or using chemicals, your eyes are sensitive and easy to damage.
- When finished with timber cut-offs, don’t burn them. Timber is often treated with chemicals that make for poisonous fumes when burnt.
- Consider anti-slip paint, varnish, or oil to help prevent accidents once your decking is finished. Remember that decking can still be slippy in wet weather, particularly in winter when the cold can turn the decking icy.
- Grinding or cutting materials often create a lot of dust, so wear protective breathers or face masks, eye protection, and ear defenders.
- When treating timber yourself, do so in a well-ventilated area. The fumes are not something you should be inhaling.
A guide to installing a simple deck
The first thing we should do is prepare the garden oversite. Ensuring the area that we build our deck on is well-prepared means that the decking will last longer once installed. It’s an important step.
Prepare the oversite
You should have already planned your decking site in your planning stage, so you can:
- Peg the corners of the decking area. Use a builder’s line or string to mark out the area between the pegs. It helps to be able to visualise the area like this.
- Within the area clear away plants, weeds, and rocks. Cut away the turf using an edger and a spade. Once cleared, use a straightedge and spirit level to ensure the decking area is even. Level out areas that aren’t even.
- If you’re laying directly on the ground, then you should lay your weed controlling fabric/landscaping fabric down now, and approx. 40mm to 50mm of gravel on top of the fabric.
- If you’re using footing posts for your decking, then remember to leave spaces for these in the fabric.
Preparing your oversite like this means that you’ll avoid damp and rot problems with your decking.
Building the deck frame
Once the area is preparing, you can start to build out the load-bearing frame, sometimes called the sub-frame. Remember that even small decks are very heavy. Build your sub-frame on-site, and when measuring and cutting the outer joists remember that the timbers will overlap at the corners.
It’s always a good idea to dry-build the decking first, without securing anything, so you can see if you can complete the build without a thin sliver of decking left or something similar.
Lay out the joist frame and lay the decking on top, making sure to create the necessary 5-8mm gaps along the length of the boards and 3mm gap and the ends.
Top tip: timber expands and contracts with temperature and moisture; so not leaving the prerequisite gaps will cause headaches down the road in colder/wetter weather.
A fixing screw or gauge screw is usually the perfect size for placing between decking boards to ensure the proper gaps are kept, or you can use off-cut pieces of wood.
Check that all gaps are the same for that polished uniform look.
Once you’re happy with how the boards look, you can begin securing them to the joists.
Securing the deck boards
If you are installing hardwood, wood-plastic composite, or PVC boards you should pre-drill your holes — this reduces the risk of splitting the boards whilst hammering nails in. All boards should be secured at each corner, plus in the centre where they pass over any internal joists.
Continue securing each board. Once you reach the edge of your sub-frame, you’re likely going to need to measure and cut the boards to size. A lot of DIYers will choose to overlap the frame edge and cut them down once they have been secured.
Finally, for this portion of the deck building, you need to sand and seal the edges of your boards. The open ends of boards are the most susceptible to rot and damp, so ensuring you sand those down and put a sealant on them is very important.
To protect your deck further, you can stain or oil the entire decking to seal it.
Finishing your simple deck
This guide was for a simple deck that rests on the ground, is not secured to the wall of the house, or raised, and doesn’t have a balustrade. For your first decking project, a smaller, simpler deck is the way to go.
A deck like this is a perfect addition to your garden, develops your burgeoning carpentry skills, and allows you to create an area to relax in with your own hands.