How to build a deck step by step

How to build a low deck - connected to a house

Planning

Plan the size and function of the deck in relationship to the house. We will only be dealing with a low deck that has a height less than one metre. After you have decided on the height of the deck mark this, with a carpenters pencil, on the wall of the house.

For example:

follow this small deck as an example of the construction process. For this deck the awning was added to the house first and then the deck added last. However both could be done at the same time if required or the deck could be added to the house without the awning at all.

The first thing that was done was to have a clear design and purpose and plan for the deck. The house has a very small landing before you walk into the door and it also used to have a small awning over it of the same size. The old awning needed to be replaced before it fell down as it was built in the 1950s. So the purpose was to replace the awning and landing with a deck and awning of a more practical size. Also the awning was to provide more shade to the front window. The landing was build with, and as part of the foundations of, the house. It was brick and in good sound condition so it could be used for part of the foundation of the deck. However, if the landing was damaged or falling over, it would need to be removed before starting.

Part of the plan for the deck was to have no step between the deck and the floor level of the house. So (100 x 50) joists were used because there was a step of about 120mm from the old land to the floor level of the house. The joists were 100mm high and the decking board were 20mm thick thus adding to the step up that we needed. You can see from this photo that joist fit under the front door step. This allows the decking boards to be installed right up to the door.

Step one: Bearers

After the plan has been checked install the ledger board or house bearer. This board is the board that is fitted to the house and forms a connection to the house. Then install the rest of the bearers so they are level with this board. For this deck you can see that three bearers have been used. One fitted to the house, one fitted to the outer awning posts (if only a deck was planned these posts would have to be installed), and one in the centre between the first two. The front bearer was bolted to the awning posts with two 12mm galvanised bolts per post.

Step two: Joists

Install your joist at 450mm spacing and nail them to the bearers. Make sure the both ends have joists up to the full length of the bearer. This means than you may have to space your last joist less than 450mm which is common. However spacing above 450mm is not allowed as this will make the decking boards too weak. Check that all posts have been bolted to the bearers with 12mm galvanised bolts. Check the joists are straight and true and ready to receive the decking boards.

Step three: Install the decking boards

This can be done by nailing the boards to the joist or by screwing down the decking boards. If nailing the board with a nail gun, use galvanised twist or ring grip deck fast nails. These are not standard nails they grip the joist and are hard to pull out. Standard nail over time work loose and this will cause the decking board to pop up. However do not use a nail gun for the ends of each board as they will spit. To overcome this problem you must pre-drill the ends of each board and hand nail them down. When you are supplied with your decking boards they will come in random lengths. This means that they will have to be cut and joined over a joist. This is done by staggering the joins across the deck. For smaller decks you can pay more and get decking boards that will span the size of your deck up to 5.4 metres thus eliminating the need to join boards. Start your decking boards on the outside and add your boards towards the house as a full board on the outside looks better.

Step five: Steps and balustrade

This deck does not require balustrade so the steps up were our step five. The steps were to be closed in and be covered with decking boards. As they were only three steps three strong box frames were made in treated pine and then the decking was installed over the top. The box frames were not just nailed but also screwed together with galvanised bulge head screws.

Step Six: Coating

With all the construction done the next important task is to protect the deck from the weather. This is just as important as getting the construction right. While many people coat the deck with cheap decking oils these only provide short term protection. Most decking oils will need to be recoated every 6 to 12 months. However the best protection and best looking coatings are acrylic based and will last well for 2 to 4 years before they need re-coating. The deck followed in this example has been coated with a premium acrylic based decking stain with is guaranteed to last for 2 to 4 years. See our decking links for more.

If your deck is above 600mm in height you will need balustrade. Please see our page in balustrade.

There are many ways to construct a deck as the construction is dependent on the design. It is true that the fundamentals remain the same as far as timber sizes and fixings (bolts and nails etc.) go. However the design does influence the ways the deck in constructed. The purpose of the deck is the first part of the deck that needs to be decided and then the look.