Ground-Level and Floating Decks in Dallas: Cost, Clay Soil and When They Work (2026)

A ground-level deck is the cheapest deck you can build, and on a flat Dallas lot it is often the easiest way to get from the back door to the yard. It is also easy to get wrong: built like a patio, it can rot early or move. This guide covers what a low or floating deck costs, what it should sit on, how Blackland Prairie clay changes the job, how close to the dirt the boards can go, and when the City of Dallas needs a permit. For the other deck styles, start with our overview of types of decks.

How much does a ground-level deck cost per square foot in Dallas (2026)?

No source we found publishes a Dallas price just for ground-level decks, so plan on Block Renovation's Dallas range for all decks: $15 to $30 per square foot in pressure-treated wood and $25 to $50 in composite. National guides price ground-level decks lower, at $10 to $20 per square foot (Bob Vila, 2023).

Only the Block Renovation rows are Dallas numbers. The rest are national, and the Bob Vila and Fixr figures date from 2023.

Bob Vila's floating range is higher than its ground-level range, and it says floating decks need additional supports to hold the decking up safely over the long term. Lawn Love puts a whole floating or freestanding deck project at $6,000 to $24,000 nationally, though it does not say how it got that range.

Bob Vila puts deck labor at $15 to $35 per square foot nationally, and Fixr at $10 to $35.

What a 12x16 low deck works out to

A 12 by 16 foot deck is 192 square feet. Here is what that size comes to at each range. These are our calculations from the sources' per-foot figures, not quotes, and the Dallas rows cover all decks, not just low ones.

For other sizes, see deck cost by size. For the full material-by-material price comparison, see the Dallas deck cost guide.

Ground-level vs floating vs low deck: what is the difference?

The words overlap. "Ground-level" and "low" describe height: Decks.com says ground-level decks are typically less than 30 inches above grade. "Floating" and "freestanding" describe how the deck is held up: it is not attached to the house.

The two meanings of "floating"

When a homeowner says "floating deck," they almost always mean a deck that is not bolted to the house. That is the meaning Fixr and Trex use.

Decking manufacturers use the word differently in their installation guides. To them, a floating substructure is framing that is not fastened down to anything. All three big composite brands forbid it:

• TimberTech: no floating substructures in any application, including on grade, on concrete or on a rooftop. The framing must be fastened to footings or to the building.
• Trex: a sleeper system must be level and must not float.
• Fiberon: over concrete, no floating systems are allowed.

By our reading, then, a "floating deck" in the homeowner sense is fine with all three brands, as long as the frame is fastened to its footings. A frame that just rests loose on blocks or on a slab is the kind TimberTech's wording rules out. If you are buying composite, ask your builder how the frame ties to each support.

What foundation does a ground-level deck sit on?

The common choices are precast concrete deck blocks, buried posts, poured concrete footings, screw piles and stackable precast forms. Fixr puts them at $50 to $500 per post or section installed (national, 2023). Decks.com also lists adjustable pedestals as an option for ground-level decks.

Bob Vila separately puts the labor to install a deck foundation at $25 to $300 per post.

To see how much the choice matters, take an example deck on 9 supports. That is an illustration, not a design; your builder sets the real count. At Fixr's installed prices, deck blocks come to $450 to $1,350, poured footings to $1,800 to $3,150, and screw piles to $2,250 to $3,600 (national, calculated from Fixr's per-post ranges).

How deep do the footings go?

The American Wood Council's deck guide (DCA 6) says footings must bear on undisturbed soil at least 12 inches below the undisturbed ground surface, or below the frost line if that is deeper. Its footing sizes assume soil that can bear 1,500 pounds per square foot, and its minimum post size is 6x6.

Dallas has its own amendment to the residential code: exterior footings go at least 12 inches below undisturbed ground, and deck footings follow the deck section of the code (R507.3). The city's climate table lists the frost line depth as 6 inches, so the 12 inch minimum is the deeper of the two. Dallas also amended the code to say footings must be designed and sealed by a Texas-registered engineer. Ask the city or your builder whether your deck's footings need an engineer's seal.

Decks.com's advice lines up: even a low deck may need frost-depth footings or approved deck blocks, so check with the building department. It also recommends a compacted gravel base under the supports to reduce settling.

Can you build a floating deck on Dallas clay soil?

Yes, but Dallas clay moves, so the supports have to bear on undisturbed soil below the surface and the deck has to be built with that movement in mind. We found no engineering source that rates how floating decks hold up on Blackland Prairie clay, so be wary of anyone who gives you a depth rule without a source or an engineer behind it.

The Blackland Prairie runs from the Texas border north of Dallas to just south of San Antonio, along I-35. Its signature soil, Houston Black (the unofficial Texas state soil), is high in smectite clay, which swells when wet and shrinks when dry. When dry, the topsoil cracks, and the cracks can be more than 4 inches wide and 12 inches deep and stay open 90 to 150 days in most years. The Soil Science Society of America says construction on this soil is often plagued by cracking from that shrink-swell movement.

Bob Vila calls a ground-level deck "essentially a patio" and says these decks are simple because they sit flat on the ground. In our view, that is the wrong way to think about it on this clay: ground that cracks open when dry and closes up after rain is likely to lift and drop anything resting loosely on top of it. That is our reasoning from the soil facts above, not a tested result.

A freestanding deck does have one advantage here. Because it is not bolted to the house, the deck and the house foundation are not locked together, so if the yard and the slab move by different amounts, the deck is not pulling on the wall. That is our reasoning, not a tested result. Trex notes a freestanding deck carries its load straight to the ground and usually needs more footings than an attached deck, so freestanding does not mean fewer supports.

What to ask a builder before a low deck goes on clay

• What will each support be (blocks, poured footings, screw piles), and why that one for this soil?
• How deep will the footings bear, and is that at least 12 inches into undisturbed soil?
• Will there be a compacted gravel base under the supports?
• How will water get away from under the deck? (See the next section.)
• Do these footings need an engineer's seal under the Dallas amendment?

Why does drainage matter more under a low deck in Dallas?

Clay soaks up water slowly, so rain that gets under a low deck tends to sit there unless the ground is graded to shed it. The Soil Science Society of America says the cracks in this clay close after rain and water then enters slowly, and heavy rain may run off before it soaks in. The soil is very hard when dry and very sticky when wet.

Decks.com says the space under a deck must be able to dry out between wet spells. The guides agree on what to do:

• Grade the soil. Decks.com says to grade under the deck so water does not stand. Fiberon says water must flow away and any flat spots where water pools should be graded or drained.
• Send it away from the house. Advantage Lumber says to grade so water runs away from the house and the deck.
• Plan extra drainage for on-grade decks. TimberTech's PRO/EDGE installation guide says on-grade decks need additional drainage provisions beneath them.

Does the deck itself need to slope? It depends whose advice you follow. Decks.com says a deck with gaps between the boards and good drainage below does not need to slope. TimberTech's PRO/EDGE guide says the deck should slope 1/2 inch per 8 feet away from the house to help run-off. That TimberTech guide is a © 2019 copy hosted by Lowe's, so check the current TimberTech guide before you rely on it. If you are using TimberTech boards, follow TimberTech.

How close to the ground can a composite deck be?

The manufacturers' minimum is about 1-1/2 inches of clearance, and all three still want air moving under the deck. Fiberon wants 6 inches where ventilation is limited, and Decks.com says most builders aim for at least 6 inches.

The TimberTech rows come from copies hosted by a dealer and by Lowe's, so ask your builder to check the current TimberTech guide.

These rules are not just advice. Trex warns that not following its guide could void the warranty. One more detail: Trex says its standard screws are too long for a 1-1/2 inch sleeper.

Heat matters too in a Dallas summer. TimberTech says all decking gets hot in the sun and darker colors feel hotter. Our deck materials for Texas heat guide covers that, and Trex vs TimberTech vs Fiberon compares the three brands.

What lumber do you need for a deck close to the ground (UC4A vs UC4B)?

Anything touching the ground, and framing less than 6 inches above final grade on concrete or treated supports without a moisture barrier, must be ground-contact lumber rated UC4A or higher. UC4B, the heavy-duty ground-contact category, is for critical or hard-to-replace parts in the ground, such as permanent wood foundations and sawn building support posts. AWPA lists sawn deck posts, joists and beams under UC4A.

The American Wood Protection Association (AWPA) says above-ground parts must be treated to UC4A or higher when any of these is true:

1. Soil, leaves or debris may build up against them.
2. The build or nearby plants block air under the deck and between the boards.
3. They sit less than 6 inches above final grade (after landscaping) on treated wood or concrete supports without a moisture barrier.
4. They touch untreated or decayed wood.
5. They get wet often.

YellaWood, a treated-pine maker, says the same in plain terms: use ground-contact lumber for parts that are hard to replace and critical to safety, or that sit less than 6 inches from the ground, have poor air circulation or have poor drainage. AWPA approved that UC4A change in February 2016.

The deck guide also requires all lumber in contact with the ground to be treated for ground contact, and allows naturally durable species only if they are 90% heartwood.

How do you prepare the ground for a low deck?

Strip the grass and topsoil, grade so water runs away from the house and the deck, lay landscape fabric, and cover it with gravel. Decks.com says not to build on grass at all, because grass and topsoil shift over time and hold moisture, which speeds up rot in the framing.

1. Remove the sod and organic material. Take out grass, weeds and topsoil.
2. Grade the ground. Shape it so water runs away from the house and the deck and does not stand under the frame.
3. Lay landscape fabric.
4. Cover it with gravel. The gravel holds the fabric down.
5. Put compacted gravel under each support. Decks.com says this reduces settling.

Skipping weed control is on Decks.com's list of common ground-level deck mistakes.

Can you build a deck over an old concrete patio?

Yes, if the slab is flat, level and sound. Composite boards go on sleepers at least 1-1/2 inches tall that are fastened down, never straight onto the concrete.

Fiberon's instructions for decking over a patio are the most detailed of the three brands:

• Fiberon is approved at 1-1/2 inches from the bottom of the board to the slab when it sits on a sleeper system.
• Sleepers must be at least 1-1/2 inches tall and wide, code-approved and rot-resistant.
• The slab must be flat and level, and floating systems are not allowed.
• Gravel, sand, dirt and pavers are not suitable bases.
• Screws go at least 1 inch into the concrete.
• Sleepers are spaced no more than 16 inches on center for a home deck and run in the same direction the water drains.
• Widen the board gaps beyond 1/4 inch, use joist tape, and use face fasteners if possible.

Trex says a sleeper system over a solid surface must be level with no dips or bumps and must support the board along its full length. It allows 1-1/2 inch sleepers and recommends 3-1/2 inches or more where debris can build up. TimberTech's guide rules out floating substructures on concrete too.

The common thread is the base. Fiberon requires the slab to be flat and level and Trex requires a level sleeper system with no dips, so a patio that has heaved or tilted on the clay is not ready for decking as it is.

Do you need a permit for a ground-level deck in Dallas?

Only a small, low, detached deck is exempt from a City of Dallas permit. On a single-family or duplex lot, a deck skips the permit only if all five of these are true:

1. It is 200 square feet or less.
2. It is not more than 30 inches above grade at any point.
3. It is not attached to the house.
4. It does not serve the required exit door.
5. It does not violate the clearance for overhead service lines.

Miss any one and you need a permit. A 12 by 16 deck (192 square feet) can pass the size test, but a 16 by 16 (256 square feet) cannot, and a low deck that sits at the back door may be serving the required exit.

Suburbs such as Plano, Frisco and McKinney set their own rules. Decks.com notes that some places do not require a permit for smaller, low, unattached decks, and says to check with the local building department. For fees, inspections and HOA approval, see our Dallas deck permit rules.

When is a ground-level deck the right call, and when is it not?

A ground-level deck makes sense when the back door is close to grade, the yard is flat and you want the lowest-cost deck. Choose a patio or a raised deck instead when you cannot keep 1-1/2 to 6 inches of airflow under the frame, the spot holds water, or the door sits well above the yard.

Block Renovation notes elevated decks are less common in DFW because the terrain is generally flat.

Pick a ground-level or floating deck if:

• The back door is only a step or two above the yard.
• You can get at least 6 inches under the joists, or you are using composite on a proper sleeper system with airflow.
• The ground can be graded so water runs away.
• You want a deck that may fit the Dallas permit exemption (200 square feet or less, detached, and the other three tests).

Pick a patio if:

• The space under the deck would be too tight for airflow, or the spot stays wet after rain.
• You want the lowest total. Fixr puts a patio, which is built directly on the ground with no elevation, at $3,000 to $8,000, against $9,000 to $20,000 for a deck of similar size (national, 2023). If that is the direction, look at a patio instead.

Pick a raised deck if:

• The door is well above the yard or the lot slopes away. Decks.com's line for ground-level is under 30 inches, so anything taller is a different job. See elevated deck cost.

What mistakes should you avoid, and what should your builder do?

The mistakes in our sources mostly come back to trapped moisture: decks built on grass, framing not rated for ground contact, solid skirting that blocks air, or no drainage. Decks.com's list of common mistakes adds missing beams, missing blocking and joists that are undersized or spaced too far apart. Composite usually needs closer joist spacing than wood.

A good builder should be able to tell you, before work starts:

• What each support is and how deep it bears in undisturbed soil.
• How the frame is fastened to the supports, so nothing "floats" in the manufacturer's sense.
• The clearance under the joists and how air gets in, with no solid skirting on a very low deck.
• Which parts are UC4A and which are UC4B.
• How the ground will be stripped, graded and covered.
• That the install follows the decking maker's guide, since Trex says not doing so could void the warranty.
• Whether your deck passes the Dallas permit exemption or needs a permit.

Archetex Outdoor Design Co., a Dallas deck builder run by owner Matthew, offers a free site visit and a written price, and can walk through these points on your lot.