How to figure out the cost of building a deck

Few DIY home projects add more personal enjoyment to a casual lifestyle than building a back garden deck. The project can be simple or complex, functional or stylish. Regardless of what you have in mind for your deck, you'll want to estimate the cost of construction ahead of time to help with the planning.


Check with the local council for planning requirements and building regulations to determine any specifications that will have to be met and which permission may be needed.

Determine which material you wish to use to build your deck. Nothing beats man-made or composite timber made of resins and plastic for durability and ease of maintenance. Most composite deck timber is made to appear natural but always falls somewhat short. Nothing will look better than a deck built of redwood or cedar. Both of these woods require a good bit of maintenance and occasional replacement of deteriorated boards. Pressure-treated timber offers economy as well as durability. Each builder will have to decide which best suits his needs and budget.

Determine the size and complexity of the deck. At times, available space dictates parameters. Your specific building skills may need to be considered and, of course, there are usually budget considerations.


Break up the plans for the deck into four basic sections to better assess the costs for each phase of construction. Part 1 will be the support structure -- how the deck attaches to the house and what sort of beams or pillars will support the framework. Part 2 will be the framework, floor joists and any bracing needed. Part 3 will be the decking itself, and Part 4 will be any superstructures wanted or required such as railings, stairs, built-in benches and built-in extras.

Check the building regs closely when determining the support structure. Some regulations require concrete pillars; others allow treated timber to make soil contact. There are likely other restrictions or requirements. Compliance with planning requirements will often dictate certain costs. List the supplies needed and add up their costs.

Draw up the framework plan, realising this part isn't as regulation-specific as support requirements. Generally, a solid, well-built framework based on plans or certain criteria will meet building regulations. Use a pre-made plan or draw up your own based on specifications extracted from plans to determine the spacing of the floor joists and distance they will span. List the materials needed and add up the costs.

Determine the cost of the flooring for the deck in one of two ways. Either determine the total square metres and break down the flooring timber into cost per square metre, or determine the number of floor boards needed and the price per board.

Decide what superstructure features are required or wanted. Here again, planning requirements are likely for certain aspects such as perimeter railings, stair cases and handrails. Determine the materials needed and their cost.

Add the prices for each part of the construction to determine the overall costs.


Don't forget incidental costs for screws, nails or other hardware as well as purchasing or renting tools to complete the project.

Things You'll Need

  • Tape measure
  • Calculator
  • Copy of building codes
  • Paper
  • Pencil
  • Ruler
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About the Author

Mike Schoonveld has been writing since 1989 with magazine credits including "Outdoor Life," "Fur-Fish-Game," "The Rotarian" and numerous regional publications. Schoonveld earned a Master Captain License from the Coast Guard. He holds a Bachelor of Science in wildlife science from Purdue University.