Planning
Stair Headroom: What to Check Before Building
How to think about stair headroom, floor openings, slab thickness, and common layout mistakes.
Headroom Is a 3D Problem
Headroom depends on the step position, the ceiling or slab above, and the stairwell opening. A side view is usually the fastest way to spot conflicts.
The problem often appears near the upper floor edge, where the user is already high on the stair but not yet inside the opening.
Model the Opening Early
Do not wait until the stair looks comfortable in plan. Add the opening length, opening offset, and floor thickness as soon as possible.
A stair with excellent rise and run can still fail if the opening starts too late.
Leave Room for Finishes
Finished floors, ceiling lining, and stair nosings can all reduce usable clearance. Use finished dimensions where possible.
When in doubt, model conservatively and verify against local requirements before construction.
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