How To Build A Deck

Please note: The pages of this site are a guideline only - Before starting your project please seek appropriate expert advice and check with your local council regulations.

timber deck and tools Adding a deck to your home is a great way to expand the value of your house, bringing indoor and outdoor living together, providing an extra area for entertaining guests or just to enjoy the outdoors with family.

First you'll need to decide on the size and shape of the deck you're going to build. This will depend on how much room you have to work with in your yard, and whether you want the deck to fully surround your house, or just covering a small area. Below are instructions for building a deck that spans 6 mtrs wide by 4 mtrs deep. Remember, these are the basics of how to build your deck, please note these are just guidelines and you'll need to check with your local council for consent, standard building practice in your area, and building restrictions.

Deck Building Materials

Posts: Ground treated 4X4 timber (or 5X5)

Concrete: For securing posts.

Joists: 4X2 outdoor treated timber

Bearers: 4X3 outdoor treated timber

Decking Timber: Outdoor treated 90mmX30mm or 90mmX16mm

Galvanized nails: 100mm nails for framework and smaller decking nails to secure decking timber. (hiring or purchasing a nail gun will save alot of time and effort when building your deck)

Please note: The pages of this site are a guideline only - Before starting your project please seek appropriate expert advice and check with your local council regulations.

Building Your Deck

Once you've decided on the size, shape and position of your deck, you'll need to setup a string-line from the house to mark out the lines and height you're going to follow when building your your deck to. Dig holes for your posts at each corner of the deck, and every 1800mm in between (maximum of 1800mm, the closer your posts are, the sturdier your deck will be.) Dig your post holes at least 450mm deep and be sure to remove any loose dirt. If you're going to be cutting your post timber (standard sizes 1.5m 1.8m and 2.4m), you'll need to re-seal the cut ends with a quality ground treatment (can be found in the paint section of your local hardware store.) Secure your posts by filling in the postholes with ready mix concrete, vibrate concrete and pack down with a concrete trowel or length of timber. Remember to ensure your posts are correctly aligned with one-another using your string-lines and spirit level and setting up pegs to hold the posts in place while drying. At this stage, leave the concrete for the required amount of time to harden.

While you are leaving your concrete to dry you can attach your ledger-board to run along the length of your house. This entails either securing a length of treated timber to your house (see your local building guidelines as specifications vary) or setting up an extra bearer and line of posts if you're unable to nail or bolt into your exterior cladding.

Once you've allowed your concrete to dry, it's time to put in place your 4X3 bearers. You can either sit the bearers on top of your posts, securing with galvanized nails and nail plates, or use coach bolts to bold the bearers to the side of each post. To achieve a solid deck surface and avoid bounce, we recommend you position your joists at no more than 350mm-400mm apart, level with your bearers. Talk to your local building store assistant about using joist hangers to secure each length of timber.

Choosing Decking Timber

Take time to wisely choose your decking timber, think about color and finish of the timber you're using, durability, strength and affordability. Popular choices for decking timber are: Kwila, Pine, Ipe, Bartu and other Soft and Hardwoods. If preferred, there are ranges of synthetic decking board materials beginning to come onto the market. Note, some woods such as Kwila will 'bleed,' meaning some of the natural oils and coloring will run after a while. This can cause your deck surface to take a silvery color over time, and the 'bleeding' oils can stain surrounding concrete where it runs off.

There are also various grades of decking timber. While thinner (90mm X 20mm) timber may help bring the cost of building your deck down, thinner timber means a weaker, bouncier surface. Likewise you may be tempted to purchase second grade timber, this will often be cheaper because of a high frequency of knots or the timber may be warped. Knot's look bad, weaken the timber, and can fall out over time leaving holes in your deck. Warped timber can be a nightmare to secure, and will often popup over time. While second grade timber can seem like a useful option, we highly recommend postponing building your deck if necessary, and using only high quality materials. For all the hard work and time you're going to be investing, it's worth spending a little extra on quality materials.

Laying Your Deck

Quick Tips For Laying Your Deck

Stagger your timber to avoid an untidy row of joins.
Instead of pre-cutting your lengths exactly, allow a little extra on the outside lengths. This way you can simply mark a line across the outside and use a skill saw to trim the edges. Pre-cutting may seem like a good idea, but a discrepancy or misplacement of 1 or 2mm can make your deck edges very untidy.

Start laying your the decking timber along the house, leaving a 5-6mm gap for drainage. Between each length use a nail or pencil head to keep a consistent 2mm gap. Position your cuts so that each joint meets over a joist. Use decking nails to secure your timber over each joist, pre-drilling your nail holes is highly recommended. A good way to ensure consistency in the gaps between each length, is to smack a nail into the joist beside each length of timber. Once you've laid your first length, hammer in a thin nail (remember you're trying to keep a 2mm gap) hard against the outside of the length, push the next length hard against the nail, hammer in another nail, then hammer in down your decking timber. This may be a little extra work, but inconsistent gaps will be noticeable.

Once you've completed securing your decking planks, check whether you're chosen wood requires any oil or varnish to seal and protect from the elements. You may also choose to add a handrail (required in some areas), or step off your deck. Adding a border with any extra decking timber lengths can be another excellent way to add finishing touches.

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