Deck Footings and Ledger Attachment Basics

By Levi Miller Reviewed by Levi Miller Published September 14, 2026 5 min read

Why these two details get the attention

When a deck collapses in the news, it is almost always one of two things: the ledger pulled off the house, or a post sank, rotted or kicked out at the bottom. Everything else on a deck is redundant to some degree; a weak joist has neighbors. The ledger and the footings do not. So they are where the code is most specific and where we spend a disproportionate share of the design and the inspection.

Footings in North County soil

A footing's job is to spread the post load over enough soil that it does not sink, and to hold the post still. The California Residential Code requires footings to bear on undisturbed soil or engineered fill, generally at least 12 inches below grade, and to be sized for the soil's bearing capacity and the load above. We have no frost line to worry about in San Diego County, but we do have everything from beach sand to expansive clay to fill dirt from a grading job decades ago, and the footing has to match the dirt. On slopes, footings may need to go deeper to find solid ground and keep the required distance from the face of the slope.

The post should never sit in or on the concrete directly. A galvanized or stainless post base anchored into the footing holds the wood an inch off the concrete so the end grain can dry; buried posts, even treated ones, are the rot we most often dig up. The porch stairs we rebuilt in North County had been sitting on dirt, which is why the old treads were soft and the stair was pulling away; the new stringers landed on a proper footing.

The ledger: how it attaches

The ledger is the board that carries one side of the deck against the house. It has to transfer its load into the house's structure, meaning the rim joist or a solid framing member, not just the stucco or siding, and not into brick veneer, which the code explicitly does not allow to carry a deck. The code's deck ledger table calls for half-inch lag screws or through-bolts in a specific staggered pattern whose spacing depends on the joist span, and modern decks also need a lateral load connection that ties the deck framing back to the house framing so it cannot pull away.

What we see in the field is ledgers nailed through stucco into nothing in particular, or attached to the house with a handful of deck screws. If you cannot see bolts or lag heads along the ledger of an existing deck, that is worth a close look.

The ledger: how it is flashed

Attachment keeps the ledger on the house; flashing keeps the house and the ledger from rotting. Water running down the wall must be directed over the top of the ledger and out, not behind it. On a stucco house that means cutting the stucco back, lapping new flashing under the weather-resistive barrier above and over the ledger below, and sealing the fastener penetrations. It is fussy work and it is exactly what was missing on the balcony we rebuilt in North County, where years of water behind an unflashed connection had rotted the joist ends and the ledger area.

Some builders now set the ledger off the wall on structural standoffs so water simply drains behind it, or build the deck freestanding on its own posts and beams a few inches from the house so there is no ledger at all. Both are legitimate solutions in our climate and both remove the most common failure point.

What to look for on a deck you already own

None of these is a reason to panic, but each is a reason to have someone probe the wood and look at the hardware. Our deck safety check answer covers the full walk-through.

Posts sitting on or in soil, or in concrete with no metal base visible.
A ledger attached with nails or screws only, or attached over brick veneer.
No visible flashing where the ledger meets the wall; staining or soft stucco just above the ledger.
Daylight or movement between the ledger and the house when someone jumps on the deck.
Rust on any connector near the ground or near the house.