What is the minimum finished exterior size of a shower in a single-family home?

What is the minimum finished exterior size of a shower in a single-family home?

• A. 28 inches
• B. 30 inches
• C. 32 inches
• D. 34 inches

Answer: (C)

The key idea is that residential showers are sized by the space you need inside the stall as well as the space the surrounding walls add on the outside. Code commonly requires a minimum interior shower floor area of 900 square inches, which corresponds to a 30 by 30 inch interior base. When you account for the finished exterior around that interior base, you have to add the thickness of the surrounding walls and finishes on both sides. With typical framing and tile/backer materials, this exterior dimension adds up to roughly two inches in total (about one inch per side). That draws the finished exterior width to about 32 inches. So, the smallest finished exterior size that still provides a 30 by 30 interior stall is 32 inches. The other options don’t fit because they either don’t accommodate the required interior space inside (28 inches, 30 inches) or are larger than the minimum (34 inches).

The key idea is that residential showers are sized by the space you need inside the stall as well as the space the surrounding walls add on the outside. Code commonly requires a minimum interior shower floor area of 900 square inches, which corresponds to a 30 by 30 inch interior base.

When you account for the finished exterior around that interior base, you have to add the thickness of the surrounding walls and finishes on both sides. With typical framing and tile/backer materials, this exterior dimension adds up to roughly two inches in total (about one inch per side). That draws the finished exterior width to about 32 inches.

So, the smallest finished exterior size that still provides a 30 by 30 interior stall is 32 inches. The other options don’t fit because they either don’t accommodate the required interior space inside (28 inches, 30 inches) or are larger than the minimum (34 inches).