Stair Measurements to Take Before a Renovation

Use finished floor-to-finished floor height whenever possible. If finishes are changing, note both the existing and expected final levels.

A few millimeters per floor build-up can change riser height enough to matter.

Measure the maximum length and width available at the lower level, plus any obstructions such as doors, radiators, beams, and built-in furniture.

For turn stairs, record the usable space in both directions, not just the total room size.

Measure the stairwell opening length, width, offset, and slab thickness. Photos from above and below help catch details that numbers miss.

If the opening will change, model the proposed opening before structural work begins.