How to Build a Floating Deck

In addition to confirming whether you may need to obtain the proper permits, if you’re thinking about building a floating deck, you’ll also want to consider its potential location, the terrain, lumber or material options, cost, and how long it will take to complete your project. If you need permits, for example, that will add to the floating deck cost and time frame.

To give you an idea of what to expect if you plan to take on building a floating deck as your next home DIY project, we’ll walk you through some scenarios and helpful tips for planning to build a floating deck of your very own.

Building A Floating Deck: Step-By-Step

If you have a lush, green backyard, you might be wondering how to build a floating deck over grass. While a floating deck may appear to “float” above the grass, this style of deck is actually built on a bed of gravel or on concrete deck blocks for stability.

In the steps outlined in this DIY floating deck example, we reference a deck situated on concrete blocks, which raises the deck for ventilation. Since the deck is not situated directly on the ground, the blocks allow the wood to dry out easier and last longer, since it reduces water absorption that can lead to rot or compromising the structural integrity of a deck.

Preparing the Deck Area

Assess your terrain where you intend to build your floating deck. If you’re wondering how to build a floating deck over dirt, you’ll first need to choose a level surface and remove the grass/rocks and other material and rake it so that your ground is level in preparation for placing the deck blocks.

Setting the Concrete Blocks

When your DIY floating deck is built on deck blocks, you create greater stability for your deck in addition to improving ventilation. To ensure a stable structure, you’ll want to take into consideration the size of your floating deck. The size of your deck, for instance, 8’ x 10’, will dictate how many concrete blocks you’ll need to create a stable, elevated surface. In addition to one block at each of your deck’s four corners, you’ll want to space blocks at regular intervals in both a horizontal and vertical direction to evenly balance the weight of your decking material and ensure structural integrity. Use a level to ensure every deck block is at the same height as one another. These blocks will form your deck’s foundation and will need to be even.

How to Build a Floating Deck Frame

The driveway or other flat space will make a good area to build your floating deck frame. Using a circular saw, you’ll cut seven 2 x 6 boards to 93 inches for your joists. You’ll also have two boards at 10 ft serving as your end joists. Lay the boards out in a rectangle and drill screws into each corner.

Position the Deck Frame

Arrange your floating deck frame over the concrete blocks. Use a framing square to help you square up the deck frame with the concrete blocks. (It also helps to have a friend or partner assist you with this portion of the project as two sets of hands are better than one!) Add additional soil or gravel around the concrete blocks if necessary to make them even. When building a floating deck on uneven ground, your biggest challenge will be to make the ground even so the deck is stable.

Install the Decking

Install your floating deck flooring by measuring all of the boards and trim them as needed so they’re even. Align one board along the edge of the deck frame and attach it with your screws. Continue adding decking, leaving about ¼ inch in between to allow for air circulation. To finish your floating deck and make it last, you’ll want to stain or seal it for protection against the elements if you’ve chosen natural wood. If you’ve chosen plastic or composite decking, you won’t need to use a sealant.

Floating Deck Costs & Material Considerations

The cost to build a floating deck will depend on multiple variables, such as the materials you plan to use to build your deck. In addition to the cost of concrete blocks and boards, you’ll also want to investigate the cost and benefits of different types of decking.

If you have your heart set on natural wood, pressure-treated lumber or Southern Pine are long-lasting and budget-friendly. Cedar and Redwood are also comparatively less rot-resistant than other natural wood options, but can also be more expensive.

Plastic or PVC decking is another cost-friendly option for a floating deck, but can be susceptible to cracks and peeling, even if they’re low to the ground On the flipside, composite decking -- made from a mix of wood fibers and synthetics -- can be found in a variety of price-points to suit your personal aesthetic. Composite decking can mimic the look of wood and can last for 25+ years, but does not require staining or as intense of a regimen of upkeep in order to maintain your floating deck.

Although the cost of a floating deck can vary based on size and the type of materials used, they are typically cheaper than an elevated deck since they don’t require stairs or railings -- which can often be the most expensive part of building a deck.

If you’re ready to find your floating deck materials, check out our find a deck builder page for long-lasting Trex products.