Does a two-story foyer count as square footage twice?

No. A two-story foyer or great room counts once, on the floor where its floor is. On the upper level, the opening to the floor below is excluded from finished area under ANSI Z765-2021, because there is no floor there. A 12 × 12 ft two-story foyer adds 144 sq ft to the first floor and nothing to the second.

What does open to below mean on a floor plan?

It's a label on an upper-floor plan marking an area with no floor, where a room on the level below rises through two stories. It's usually drawn with an X or diagonal lines inside the opening. The area marked open to below is left out of the upper floor's square footage.

Does a catwalk or interior balcony count as square footage?

Yes, the floored part does. A catwalk or balcony inside the house that overlooks a two-story room is enclosed, finished floor on the upper level, so it counts with that level. Only the open part of the opening is excluded. Exterior balconies are different: they aren't enclosed, so they're never finished area.

Does a loft count as square footage?

A finished loft counts on the upper level like any other room, as long as it meets the ceiling-height rules: 7 ft, or under a sloped ceiling at least half the loft at 7 ft or more with nothing under 5 ft counted. The open area the loft overlooks doesn't count upstairs.

Do vaulted or cathedral ceilings add square footage?

No. Square footage is floor area, so a tall ceiling adds nothing. A vaulted living room counts once, at its floor area, the same as it would with an 8 ft ceiling. That's why a house with big two-story spaces can have less square footage than its size from the street suggests.

Does filling in an open-to-below area add square footage?

Yes. Once the opening has a floor and the new space is finished, connected and meets the ceiling-height rules, it counts as finished area on the upper level. Floor area that used to be open to below becomes ordinary upper-floor square footage.

Guide

Open to Below: How Two-Story Spaces Are Counted

A two-story foyer or great room counts once, on the floor it sits on. Openings to the floor below aren't counted upstairs. With a worked example.

Updated October 12, 2026 · FloorFigures

Short answer

A two-story foyer or great room counts once, on the lower floor, where its floor is. On the upper level the opening is excluded: ANSI Z765-2021 doesn't count openings to the floor below. Floored catwalks and interior balconies over the opening do count upstairs. A 12 × 12 ft two-story foyer adds 144 sq ft to the first floor and nothing to the second.

Square footage is floor area. A two-story room has one floor, so it's counted once, however much air sits above it. The mistake is easy to make, though: measure the second floor around its outside walls and the opening comes along for free. Here is how to handle openings, catwalks and stairwells, with a worked example.

Does a two-story room count twice?

No. ANSI Z765-2021, the standard appraisers use for Fannie Mae and Freddie Mac loans, says openings to the floor below can't be included in the square footage calculation. The room's floor is counted on the level where it sits. On the level above, the opening has no floor, so it isn't area.

It can feel wrong, because a two-story great room is a bigger, more expensive space than a one-story room with the same floor. But square footage only measures floor. The extra height is a feature of the room, and it's described as one (in a listing's remarks or an appraisal's comments), not added as area.

The great room's floor counts on the first floor. Upstairs, the opening is subtracted from the second floor.

How to measure the opening

Measure the upper floor around its outside walls, as you would any level, then subtract the opening. Measure the opening at floor level, along the edges where the upstairs floor ends, usually under the railing or half wall. If the opening isn't a rectangle, split it into rectangles the same way you would an irregular room.

On a floor plan, openings are labeled "open to below" or "open to foyer," and usually drawn with an X or diagonal lines. Check the upper-floor sheet for every one: a plan can have a two-story foyer, a great room and a smaller opening over a landing. Measure the opening itself rather than assuming it matches the room below: a catwalk, a landing or a loft often covers part of it.

Catwalks, balconies and lofts over the opening

Catwalks and interior balconies are floored, enclosed space on the upper level, so they count there. Subtract only the part of the opening that is actually open.
Lofts that overlook a two-story room count upstairs like any room, subject to the ceiling height rules, which matter when a loft is tucked under the roof slope.
Exterior balconies aren't enclosed or usable year-round, so they're never finished area. They can be listed separately.

When the two-story room starts below grade

Some houses open a walkout lower level up into the main floor: a two-story family room whose floor is in the basement. The rule doesn't change. The room's floor counts once, on the level where it sits, and that level is partly below grade, so the room is below-grade finished area. On the main floor, the opening is excluded. The house gets no above-grade credit for that room at all. See does a finished basement count.

What about the stairwell?

A stairwell is an opening too, but it's the one exception. Under ANSI Z765, stair treads and landings count on the floor the stairs descend from, up to the area of the floor opening. So the stairwell stays in the upper floor's area; don't subtract it as open to below. If the opening is bigger than the stairs, as with a stair wrapped around an open well, only the treads and landings count and the rest of the opening is excluded. Details in how stairs are counted.

Worked example

A two-story house, 50 × 36 ft on both floors. It has a two-story foyer (12 × 12 ft opening upstairs), a two-story great room (18 × 20 ft opening) crossed by a 4 ft wide catwalk, and a stair in a 3.5 × 12 ft opening.

Line	Calculation	Area
First floor	50 × 36	1,800 sq ft
Second floor, outside walls	50 × 36	1,800 sq ft
Less foyer opening	12 × 12	−144 sq ft
Less great room opening, net of catwalk	(18 × 20) − (4 × 18) = 360 − 72	−288 sq ft
Stairwell	Filled by the stairs; stays in	0
Second floor finished	1,800 − 144 − 288	1,368 sq ft
Above-grade total	1,800 + 1,368	3,168 sq ft

Common mistakes

Mistake	Total for the house above	Error
Counting both floors by their outside walls	3,600 sq ft	432 sq ft (13.6%) too high
Also subtracting the catwalk	3,096 sq ft	72 sq ft too low
Also subtracting the stairwell as open to below	3,126 sq ft	42 sq ft too low

The first one matters most. At a $700,000 price, the house is $221/sq ft on the correct 3,168 sq ft, but looks like $194/sq ft if the openings are counted. Listings and marketing materials aren't bound by ANSI Z765, so if a two-story house's listed size looks generous, check whether the openings were taken out. See why square footage numbers differ.

Handling openings in FloorFigures

FloorFigures is free and runs in your browser. Trace the upper floor, then draw each opening as an Open to below area (or use a cutout). It's subtracted from that level, while overlapping areas are merged so nothing is counted twice, and the excluded area appears in the totals. Mark the stairwell as Stairs instead and it stays counted on the floor it descends from. With areas already measured, the ANSI Z765 GLA calculator does the same math, and the ANSI Z765 guide covers the rest of the standard. For the whole house, including the garage, follow how to measure a house.

Questions

Does a two-story foyer count as square footage twice?: No. A two-story foyer or great room counts once, on the floor where its floor is. On the upper level, the opening to the floor below is excluded from finished area under ANSI Z765-2021, because there is no floor there. A 12 × 12 ft two-story foyer adds 144 sq ft to the first floor and nothing to the second.
What does open to below mean on a floor plan?: It's a label on an upper-floor plan marking an area with no floor, where a room on the level below rises through two stories. It's usually drawn with an X or diagonal lines inside the opening. The area marked open to below is left out of the upper floor's square footage.
Does a catwalk or interior balcony count as square footage?: Yes, the floored part does. A catwalk or balcony inside the house that overlooks a two-story room is enclosed, finished floor on the upper level, so it counts with that level. Only the open part of the opening is excluded. Exterior balconies are different: they aren't enclosed, so they're never finished area.
Does a loft count as square footage?: A finished loft counts on the upper level like any other room, as long as it meets the ceiling-height rules: 7 ft, or under a sloped ceiling at least half the loft at 7 ft or more with nothing under 5 ft counted. The open area the loft overlooks doesn't count upstairs.
Do vaulted or cathedral ceilings add square footage?: No. Square footage is floor area, so a tall ceiling adds nothing. A vaulted living room counts once, at its floor area, the same as it would with an 8 ft ceiling. That's why a house with big two-story spaces can have less square footage than its size from the street suggests.
Does filling in an open-to-below area add square footage?: Yes. Once the opening has a floor and the new space is finished, connected and meets the ceiling-height rules, it counts as finished area on the upper level. Floor area that used to be open to below becomes ordinary upper-floor square footage.