How many drywall sheets to purchase?
Estimated number of drywall sheets to buy for a certain room size
1 Room size is an actual width and length of a standard room in feet.
2 Floor area is measured in square feet and it is an identical parameter to flat ceiling dimensions.
3 Number of door includes all, up to 36” wide and 80” high, prehung, sliding or bi-fold doors in the room.
4 Number of windows includes all, up to 48” x 54” windows in the room.
5 Number of drywall sheets calculated as a total number of 4’x8’ sheets necessary to purchase for installation in a certain room with 96” high walls and flat ceiling with no skylights. Drywall for closets in bedrooms should be estimated separately.
Formula for calculating a number of drywall sheets for one standard rectangular room:
N = ((P x H + Ac) / Ad) + 10%
P – room perimeter
H – walls height
Ac – ceiling area
Ad – area covered by a single drywall sheet
10% - typical waste factor
All numbers in the chart are accurate for standard with simple flat ceiling rooms accounting installation of 48” x 96” drywall sheets on walls and ceiling. Calculation of drywall for installation in homes with open floors, rooms with cathedral, vaulted, coffered, tray ceilings or irregular dimension rooms should be done based on exact coverage area measurements with adding 10% – 15% as a waste factor.
Calculating number of drywall sheets for bathroom
Moisture and mold resistant drywall should be installed in rooms with potentially high moisture level including bathrooms powder or laundry rooms. For that reason, always estimate a number or gypsum boards for bathroom separately. In addition, drywall cannot be used as a backing surface for stone, porcelain or ceramic tile installation. Setting particular tile on mortar should be done only on top of cement of fiber cement backer boards screwed directly to studs. With all that in mind, always purchase adequate materials. For example, for 84”wide, 108” long, and 96” high bathroom with approximately 80 ft2 of walls covered by 12” x 12” porcelain tile, high chances are, you need to buy six 3’ x 5’ cement backer boards and 9 sheets of 4’ x 8’ moisture resistant drywall.
Calculating coverage area by one sheet of drywall
Most gypsum boards sheets are 48” wide and 96” long with 32 ft2 coverage area. Some sheets sold 108”, 120”, or 144” long, and coved 36, 40 or 48 square feet respectively.
Estimating walls and ceiling square footage of a whole house
There are two ways of determination what is actual ceiling and walls coverage area for calculating how many square feet of drywall should be installed:
1. Analyzing house plan
Experienced drywall contractor is able to calculate interior walls and ceiling coverage by reviewing architectural drawing. This option might work only during building a new house and in case there won’t be any changes made to the plan during construction.
2. On-site measurements
Getting exact measurements of interior walls and ceiling in every room where drywall should be installed is common technique for defining actual square footage. While remodeling a house, it is the only way to determine the project size. Even on a new construction, especially if it is a custom build home, a contractor will inspect house interior before coming up with any numbers.
Estimated number of drywall sheet for a whole two story 3 bedrooms, 2 bathrooms 2,300 ft2 house.
6 Drywall sheet dimension is actual width and length of gypsum board sheet in feet.
7 Walls and ceiling area is an actual area in square feet where drywall should be installed.
8 Numbers in the chart are approximate and might vary due to variations in house plans.