Accentra (Yale) 356 Double Cylinder W/Thumbturn inside Mortise Deadbolt

The Accentra (Yale) 356 is a double cylinder mortise deadbolt with thumbturn inside, also referenced as the Yale 356G. The deadbolt is operated by key from the outside and by key or thumbturn from the inside, with one critical distinction: the inside thumbturn will retract the deadbolt but will not project it. Projecting the deadbolt from either side requires the key. The lock uses a classroom function mortise lock body. Backset is 2-3/4 inches, throw is 1 inch laminated stacked steel with hardened pin. For 1-3/4-inch doors only. Non-handed and field reversible. SKU: 356.

What the Yale 356G does and how the thumbturn-only retract function works

The 356 is classified as a double cylinder deadbolt because a key is required from both sides to project the deadbolt. The thumbturn on the interior face is not a full operating mechanism: it can only retract a bolt that the key has already projected. To throw the deadbolt to the locked position, a key must be used from inside or outside. To unlock it from inside, the thumbturn is sufficient. This is the classroom function: an authorized person with a key controls whether the door is secured, but anyone inside can retract the bolt and exit.

This configuration is used on institutional doors, school room entries, hospital ward entries, and any door where the security policy requires the locking person to use a key credential to secure the deadbolt, while always allowing egress from inside without a key. It's a meaningful operational distinction from a standard double-cylinder deadbolt where the key is required from both sides to both lock and unlock. For the thumbturn-only mortise deadbolt where no outside operation is possible at all, the Accentra Yale 354 Exit thumbturn-only mortise deadbolt is also stocked. For auxiliary deadbolts in other configurations, the auxiliary deadbolts section covers the available range.

What the laminated stacked steel deadbolt and adjustable front plate provide on the 356

The deadbolt is constructed from laminated stacked steel with a hardened anti-saw pin insert and a 1-inch throw. Laminated stacked steel bonds multiple layers of steel into the bolt body, providing resistance to sawing and cutting attacks that can defeat a solid steel bolt of the same dimensions. The hardened insert rotates freely when a cutting tool contacts the bolt face, preventing the blade from gripping the material.

The front plate measures 4-5/8 inches by 1-1/8 inches and is available in brass, bronze, or stainless steel. It adjusts to accommodate both flat and beveled door edges, with a bevel adjustment of 1/8 inch in 2 inches. The heavy wrought steel case is zinc plated and dichromated. The standard included strike is the 30S model at 3-1/2 inches by 1-1/8 inches. The optional ANSI/BHMA A156.115 strike (model 545N, 4-7/8 inches by 1-1/4 inches) is available separately for installations requiring the larger format.

How the Yale 356G fits into a mortise lock installation and what backset compatibility to confirm

The 356 is a mortise deadbolt, requiring a mortise pocket machined into the door edge for installation. The backset is fixed at 2-3/4 inches and no alternative backset is available. The lock is designed for 1-3/4-inch thick doors only. The front plate is adjustable for flat or beveled door edges. The lock is non-handed and easily field reversible, covering both left-hand and right-hand door configurations without a separate ordering designation.

For key cylinders and key blanks compatible with the cylinder used in the 356 deadbolt, the cylinders, cores, and keys section covers the available options. For mortise locks at American Locksets that pair with the 356 auxiliary deadbolt in a complete door opening, the mortise locks catalog is available. For the full commercial lock range, browse the commercial locks section.

Backset is 2-3/4 inches only. Confirm mortise door prep and 1-3/4-inch door thickness before ordering. Also referenced as: Yale 356G, Yale 356g door handle, Yale 356g lock.