Freestanding vs attached decks

The structural difference

An attached deck hangs one end of every joist on a ledger bolted to the house, and carries the other end on a beam at the outer edge. Two lines of support, one of which is the building.

A freestanding deck carries both ends on its own beams — one near the house and one at the outer edge — each on its own posts and footings. The deck touches the house only as a weather detail, not as structure. It is sometimes called a self-supporting or floating deck, although floating more usually means a low deck on blocks.

When freestanding is the only option

The choice disappears whenever the wall cannot carry a ledger. That covers more houses than people expect:

• Brick or stone veneer, which is cladding rather than structure.
• Stucco or EIFS over foam sheathing — fasteners through more than half an inch of sheathing lose their rating.
• A cantilevered floor such as a bump-out or bay window.
• Hollow block without grouted cells and proper anchors.
• Any band joist that probes soft, which usually means water has been getting behind an existing ledger for years.

The ledger board guide goes through each of these in more detail, and the ledger calculator gives fastener spacing where a ledger is possible.

What freestanding costs extra

On a typical 16 by 12 deck, going freestanding adds a second beam the full length of the deck and roughly doubles the footing count — three or four more holes, more concrete, more posts and more post hardware.

Against that, you save the ledger board, the structural fasteners, the flashing and the lateral load connectors. The net is usually several hundred to a couple of thousand dollars more for freestanding on a deck this size. Check your own numbers with the framing calculator.

Why builders often prefer freestanding anyway

1. The ledger is the deck's single biggest structural risk and the leading cause of collapse. Removing it removes that risk entirely.
2. No hole through the weather barrier means no path for water into the band joist, which is the most common cause of hidden rot.
3. Inspections are simpler. The ledger connection and its flashing are the parts inspectors look hardest at.
4. The deck and the house can move independently, which matters on expansive soils and in regions with significant frost movement.
5. Future work on the siding, sheathing or wall is far easier when nothing is bolted through it.

Details specific to freestanding decks

The house-side beam sits a little away from the wall, so leave a gap — typically an inch or two — between the deck framing and the siding for drainage and airflow. Do not caulk that gap closed; it is doing a job.

Lateral stability is the one thing a ledger provides for free. A freestanding deck resists side-to-side movement through its own bracing: knee braces between posts and beams, or diagonal bracing under the frame. Codes are specific about this, and it is the part most often missed on homeowner-built freestanding decks.

Finally, decide the deck height with the threshold in mind. Because a freestanding deck is not tied to the house, there is nothing stopping it settling differently over time — keep a deliberate step down from the door rather than building flush, so a small settlement does not become a trip hazard at the threshold.