A deck does not need to be attached to the house. The International Residential Code recognizes both attached and freestanding decks, and either is a legitimate way to build. What changes with the choice is the structural detailing, the hardware, and sometimes how zoning treats the finished structure.
In a few situations the choice is made for you. Everywhere else, it is a design decision with real trade-offs.
When Freestanding Is Your Only Option
If the wall you would attach to is covered in stone or masonry veneer, you cannot bolt a ledger to it. Veneer is a decorative surface, not a structural one, and it cannot safely carry a deck’s weight. In that case the deck has to stand on its own supports.1UpCodes. R507.9 Vertical and Lateral Supports at Band Joist
Beyond that specific restriction, homeowners often choose freestanding designs when they want to avoid drilling into the exterior wall, when the band joist behind the siding is not sound enough to carry a ledger, or when the deck sits at a height or location where connecting to the house would be awkward.
What Freestanding Construction Requires
An Extra Line of Support
A freestanding deck carries its full weight on its own posts and beams, including along the side nearest the house where an attached deck would rely on a ledger. That means an additional row of footings, posts, and a beam running parallel to the house wall. You are effectively building two support lines instead of one.
Bracing Against Sway
Every deck has to resist side-to-side movement, but a freestanding deck cannot borrow stability from the house. The code requires lateral bracing so the structure does not rack under horizontal loads.2UpCodes. AM109.1 Deck Bracing
If you do not use diagonal or knee bracing, the code allows posts to be embedded directly in the ground instead, but limits how tall those posts can be. A 4×4 post embedded this way can extend no more than 4 feet above grade. A 6×6 can reach 6 feet. Anything taller, or any smaller cross-section, has to be diagonally braced.2UpCodes. AM109.1 Deck Bracing
What Attached Construction Requires
The Ledger Board
An attached deck transfers part of its load into the house through a ledger board, which is a pressure-treated board of at least 2×8 nominal dimension fastened to the house’s band joist. The code specifies fastener spacing based on joist span and the sheathing between the ledger and the band joist. Lag screws and bolts must be hot-dipped galvanized or stainless steel.1UpCodes. R507.9 Vertical and Lateral Supports at Band Joist
Lateral Load Connectors
Bolting the ledger to the band joist handles vertical weight, not the outward pull that tries to separate the deck from the house. The code requires hold-down tension devices in at least two locations along the deck, each within 24 inches of the deck’s end, with a minimum capacity of 1,500 pounds each.1UpCodes. R507.9 Vertical and Lateral Supports at Band Joist Ledger failure is the leading cause of deck collapses. These connectors are not a formality.
Flashing
Water trapped between the ledger and the wall causes rot and eventual structural failure. Flashing above the ledger must extend at least 2 inches up the wall and at least 4 inches out from the face of the ledger. If a window or door sits less than 2 inches above the ledger, the flashing has to run up to the bottom of that opening.1UpCodes. R507.9 Vertical and Lateral Supports at Band Joist Flashing can be omitted only when the ledger is spaced at least a quarter inch away from the wall so that water can drain and air can circulate behind it.
Requirements That Apply Either Way
Footings and Frost Depth
Footings for any deck, attached or freestanding, have to rest on undisturbed soil and extend below the local frost line. Frost depths across the United States range from 0 inches in southern coastal areas to more than 60 inches in parts of the northern Midwest and mountain West. Footings placed above the frost line can be lifted by freezing moisture in the soil, a process called frost heave, which tilts the deck and eventually breaks connections. Your local building department will tell you the exact depth required.
Load Capacity
Residential decks must support a minimum live load of 40 pounds per square foot and a dead load of 10 psf. Live load covers people, furniture, and anything set on the deck. Dead load covers the weight of the structure itself.3UpCodes. R507.6 Deck Joists In areas with heavy snow, if the ground snow load exceeds 40 psf, the deck must be designed for the higher figure.
Joist size, spacing, and species determine how far a joist can span. A 2×8 Southern Pine joist spaced 16 inches on center can span up to 11 feet 10 inches. A 2×10 of the same species at the same spacing reaches about 14 feet. Cantilever length, the distance a joist extends past its supporting beam, is limited to one-quarter of the joist’s main span.3UpCodes. R507.6 Deck Joists
Guardrails and Stairs
Any deck surface more than 30 inches above the ground at any point needs a guardrail at least 36 inches tall, measured vertically from the deck surface. Openings between balusters cannot allow a 4-inch sphere to pass through.
Guardrails along stairs drop to 34 inches minimum, measured from a line connecting the stair nosings. On the open side of a stairway, the triangular gap formed by the tread, riser, and bottom rail cannot allow a 6-inch sphere to pass through. Stair treads must be at least 10 inches deep and risers no taller than 7¾ inches. The largest riser or tread cannot differ from the smallest by more than ⅜ inch.
How the Choice Affects Zoning
Zoning ordinances usually treat an attached deck as part of the house. It has to stay within the same building envelope and respect the same setback distances, often 20 to 30 feet from rear property lines and 5 to 15 feet from side lines, though those numbers vary widely.
A freestanding deck is often classified as an accessory structure, which can carry more relaxed setbacks, sometimes allowing the deck as close as 5 feet from a side or rear property line. That advantage disappears in many jurisdictions once the deck rises more than 30 inches above grade, at which point the stricter rules that apply to the main house kick back in. Review your property’s plot plan and local zoning map before you finalize the design.
One boundary worth checking: if your property carries a utility or storm drainage easement, you generally cannot build any permanent structure inside it, including a deck of either type. A deck built over an easement may have to come down at your expense if the utility needs access.
Permit Implications
Most decks need a permit regardless of whether they attach to the house. The IRC exempts a deck only when it meets all four of these conditions at once: no more than 200 square feet, no more than 30 inches above grade at any point, not attached to the dwelling, and not serving a required exit door.4UpCodes. GSA Residential Code 2024 – Chapter 1 Scope and Administration
Note what this means for the attached-versus-freestanding choice. An attached deck always needs a permit, even a small low one. A small, low, freestanding deck that does not serve a required exit door may not. Many local jurisdictions apply stricter thresholds than the IRC, so confirm with your building department before assuming your project is exempt.