How to Build Simple Square Decking

Last Updated: June 17, 2022 References

In this article you will learn how to build simple square decking. This is the most inexpensive shape to build and has minimal waste. It's also a great option for beginners. Read on for simple steps to build your own deck!

1

Pick a location for your decking.

Take measurements and decide what features you want. Do you want it connected to the house? do you require posts, spindles, and a handrail? Will it require stairs? Also you may consider different species of wood as each has different properties and some require less maintenance than others.
- Let's say your decking is going to be in the middle of your back garden, freestanding with no handrail or steps. If your decking is 12 feet (3.7 m) x 12 feet (3.7 m) then ensure you buy 14 feet (4.3 m) lengths to reduce cost and waste. You will also need 6"x2" lengths for the subframe.

2

Check that the ground is level or close to level.

If it is spot on then the decking can be laid straight down on top without the need of supports. If it is not level then digging in one area or supporting in another may be necessary. The easiest way to support a deck this size without posts is to dig five holes. One at each corner and one in the middle. These holes can be filled with combinations of sand/shingle and blocks, or with concrete.
- Take into consideration the soil's integrity when choosing a method. If your soil is solid then two blocks, sand and shingle may suffice. If your soil is bad then maybe consider a slightly larger hole filled in with concrete. Decking with posts and handrail can be supported by digging holes, placing the posts in plumb and filling with concrete.
- Remember that your deck needs to be off level slightly to allow rainwater to flow off its edge. Water flow should move the same direction as the decking surface. Supporting blocks or infills can be levelled with a straight edge and a level sitting on top.^{[1]
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3

Clear the area you will be covering

Then, lay down landscaping cloth or a weed barrier. Failure to take this step will result in grass and weeds appearing up through the deck at a later stage. Once you have this laid, cover sparingly with gravel to keep it in place.

4

Build your subframe.

Cut 2 lengths of 6x2 at 12 feet (3.7 m). Hold the two side by side and mark 16" centres. Count how many markings you have and add 2 for either end. In this case you require 13 internals. Now cut the internals by subtracting 4" (thickness of two externals) from 144"(12 ft) leaving you with 140"

5

Connect the framing

Once all your cutting is complete, the frame can be nailed or screwed together. Make sure that any humps in the wood are pointing up and that all the butt joints are tight. Now you need to cut two lines of bridgers. Mark the two outside internals at 4 feet (1.2 m) and 8 feet (2.4 m). Strike the two lines and screw or nail your noggins either side of the line. Once this is complete your deck frame can be fixed into location.
- NOTE. Only use galvanized nails or decking screws, 4" preferably.^{[2]
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6

Connect your deck to its supports.

Use brackets, braces or stakes. Be sure to recheck that its slightly off level to the side. Once the frame is in position you can start cutting the decking for the outside perimeter to hide the the subframe. Cut your perimeter boards at 45 degrees angles to butt together at the corners and screw into place.
- NOTE. Use decking screws as they are specially coated for this job. Normal screws may decay and snap over time causing twisting. If the board thickness is 30mm then 70mm screws are ideal.

7

Lay your decking.

Place the first board down. It should have an overhang of 15-30mm along the edge and overhanging evenly either end (this end waste will be cut straight once all boards are fixed). Some people don't use an overhang but it looks better and allows rainwater to drip free from the face in the same way an external windowsill prevents water dripping down a wall. If you don't like this method then screw it flush.
- Allow a constant gap of 3mm-8mm for expansion between the boards as they will absorb water in the winter and dry out and shrink in the summer. Failure to do this will result in the boards lifting, splitting and not drying out. This will lead to rotting and a very short life expectancy.^{[3]
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8

Create a uniform overhang.

Wait until all the boards are screwed down. Then, you can run a circular saw down the two sides to leave a uniform overhang of 15-30mm all round. You can round the ends of the boards with a router if required.^{[4]
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9

Oil and use it.

Just remember to treat it or oil it at least once a year. Ideally, you'd even treat it as frequently as every six months.^{[5]
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Community Q&A

Question

How do I make sure the deck is square?

Andrej Waliłko

Community Answer

When building your subframe, measure diagonally from corner to corner. If the measurements match, your frame is square. If they don't, push the two corners that are further away (the long measurement) back together a little and remeasure. Measure again before and after your first deck board is installed and every few boards as well to ensure it stays square while building.
Question

Just had a small deck started (8x10). It is framed, the deck boarded in and attached to my house. It is low to the ground. Carpenters have only 3 supports on the outside. Is this enough?

Andrej Waliłko

Community Answer

4x4 supports should be no more than 8 feet apart, and most builders will place them at 4 feet. So, three across a 10 foot span sounds OK. If 2x8s are used for the joist material, you shouldn't have any bowing. A completely separate question is how deep the 4x4 footings were placed. They must be below the frost line or they will heave and rise/sink when it rains or over the winter. Different states have different codes, but in Michigan, concrete footings need to be 4' below ground level with a bracket to permanently affix a treated post.