House Drywall Calculator

How the estimate is built

Instead of one multiplier, the estimator adds up three surfaces from the floor area, the number of stories and the ceiling height.

• Ceilings: equal to the floor area of every story. Choose walls only and they drop out of the board, mud, tape and screws.
• Outside walls: the footprint is treated as a rectangle half again as long as it is wide. Its perimeter times the ceiling height gives the inside face of the outside walls, less 12% for windows and exterior doors.
• Interior walls: 0.09 linear ft per sq ft of floor for an open plan, 0.12 for a typical one with bedrooms, baths and a hall, and 0.16 for many small rooms and closets. They are boarded on both faces.
• Sheets: board area plus 10% waste, divided by 48 sq ft for 4x12 or 32 sq ft for 4x8.

The result is a wall-to-floor ratio that changes with the house. For 1,500 sq ft on one level with 8 ft ceilings, a typical plan comes to 3.66 sq ft of board per sq ft of floor, an open plan 3.18 and a plan with many rooms 4.30. Ceilings are 27% of the typical total and walls the other 73%. The same floor area split over two stories has a smaller footprint with more outside wall per square foot of floor, 5,954 sq ft in all.

The footprint shape, opening share and interior wall density are our planning assumptions, not measured data.

Checked against published multipliers

Drywall finisher Myron Ferguson, writing in Fine Homebuilding, multiplies living-area floor space by 3.5 for 8 ft ceilings and 3.82 for 9 ft ceilings, and figures the garage separately. The typical density was set so this model lands near those figures: 3.66 and 3.99 for a 1,500 sq ft one-story house. The U.S. Geological Survey put an average new 2,000 sq ft home at about 6,144 sq ft of wallboard in 2001, about 3.1 times the floor area.

What the labor range means

The cost range is labor to hang and finish, at the site's national planning range of $1.20 to $2.50 per sq ft of board, not per sq ft of floor. For the typical 1,500 sq ft house that is $6,592 to $13,733. Board and materials are extra, and the state labor cost pages scale the range to local wages.

Common mistakes in a whole-house estimate

• Multiplying floor area by the board area of one room. Interior walls take board on both faces, so a house needs far more than its floor area suggests.
• Using one multiplier for every house. Ceiling height, stories and how cut up the plan is all move the ratio; a 9 ft ceiling alone adds about a tenth.
• Counting the garage in the floor area. Its board is often 5/8 in type X under the fire separation rules, so it is figured on its own.
• Leaving out the ceilings, or counting them twice on a two-story house. Every story has one ceiling equal to its floor area.
• Ordering from the estimate. Openings, closets, soffits and vaulted ceilings change the real count, so measure room by room before buying.
• Pricing labor per sq ft of floor. Contractor rates are per sq ft of board, which in this model is about three to five times the floor area.