Egress, Leasable Area, and a Tenant's Interconnecting Stair
A developer is designing an 88,000 gsf, four-story speculative office building, Type IIB, fully sprinklered, on a 22,000 sf floor plate with a central core holding two exit stairs. The pro forma needs 20,000 rentable sf per floor. An anchor prospect will lease floors two and three only if the two floors are connected by an open interconnecting stair, which requires a 12-by-16-foot slab opening. Review of the 70 percent design set shows a 62-foot dead-end corridor serving four corner offices at the northeast, and a 128-foot common path of travel from those offices to the nearest exit stair. The permit set is due in six weeks. The developer's leasing broker has asked the architect to "get a variance" for the corridor conditions, noting that the building is sprinklered and that the concept plan was already approved.
1. Evaluate the two corridor conditions and explain what, if anything, a variance can do for them.
Read the worked answer
Dead end. In a sprinklered Group B building the dead-end limit is 50 feet. A 62-foot dead end serving four offices is a violation, not a design preference - 12 feet over.
Common path of travel. The limit in a sprinklered Group B occupancy is 100 feet; 128 feet exceeds it by 28 feet. This is the harder condition, because it is measured from the most remote point to the point where two distinct egress paths exist. Widening the corridor does not fix it.
Variance reality. Variances are granted for practical difficulty where the applicant demonstrates equivalent safety, and they are typically site-driven rather than plan-driven. A corridor the team itself drew 62 feet long is a self-created condition; boards almost never grant relief from egress requirements for those. The broker's sprinkler argument is also backwards - the sprinklered numbers are already the generous limits.
What actually fixes it. Either (a) add a third exit at the northeast corner - roughly 300 to 350 sf per floor plus a 1-hour enclosure - or (b) reconfigure the northeast corner into a corridor loop so the dead end disappears and the common path shortens below 100 feet. The loop usually costs less area, perhaps 300 to 400 rentable sf per floor. At $34 per sf per year, 400 sf across four floors is about $54,400 per year of rent; capitalized at a 6 percent cap rate that is roughly $900,000 of asset value. Either fix is cheaper than a permit appeal that delays the anchor lease.
2. The developer wants the interconnecting stair and the shortest possible permit path. What do you recommend sequencing, and what must be verified about the slab opening?
Read the worked answer
Fix egress first, on the record. The corridor conditions are independent of the stair and will be caught at plan review regardless. Turn a correction into a decision now: issue a sketch showing the loop versus the third stair, give the developer the area and cost numbers beside it, and get the choice confirmed by email. A six-week permit deadline cannot absorb a first-cycle egress rejection.
The interconnecting stair. Two questions to settle with the authority having jurisdiction before drawing it:
- Is enclosure required? A slab opening connecting two stories may be left unenclosed in a sprinklered building within limits on opening size and arrangement. If the opening does not qualify, the stair must sit inside a 1-hour shaft with protected openings, which reorganizes the core and the demising lines.
- Does the stair count as an exit? If it is an interior exit stairway it must be enclosed; if it is an unenclosed convenience stair it is not an egress path and cannot be counted toward egress capacity - which matters, because the tenant will want it counted.
Sequence. Parallel, not serial: (a) a one-page code analysis and a pre-submittal meeting covering both the corridor fix and the stair opening, this week; (b) the corridor fix goes into the permit set immediately; (c) hold the stair opening on a deferred submittal only if the developer accepts a shell permit plus a later tenant-improvement permit, and confirm with the AHJ that this path is acceptable before promising the date.
Also check the structural edge at the opening - a 12-by-16 hole in a two-way slab on a 22,000 sf plate can require new beams - and confirm the shaft does not cross the tenant demising line on the other two floors.