A.Lynn Underwood, an engineer, licensed contractor, and building code official in Norfolk, Va., responds: If a basement measures less than 200 square feet and is used only for mechanical equipment, no windows are required by the IRC, though foundation ventilation, crawlspace access, and flood vents may be needed. Otherwise, all basements with full-height foundation walls must have at least one emergency egress window. Local codes may require additional fenestration for natural lighting and ventilation.

But even if you intend for the basement to be nonhabitable, installing full-height precast foundation walls could allow for conversion to living space later on, in which case section R310 of the 2006 IRC requires that every sleeping area have an emergency egress opening, with a sill that isn’t any higher than 44 inches above the floor. While the IRC does not deal with hypothetical situations, it does allow jurisdictions to consider safety concerns that are likely to arise after the final inspection is approved.

Your best bet is to be clear about your goals with your building official. If you want to offer your customers the option of adding living space in the future, either specify window openings in the precast panels or design the foundation wall with fenestration knock-outs that can be easily removed.