Vaulted Ceiling Drywall Calculator
Enter the room, its wall height and the pitch of the ceiling. The calculator works out the sloped ceiling and the two gable triangles, lays out every surface and shows how many more sheets the vault takes than a flat ceiling.
- Cathedral ceiling
- Gable triangles
- Vs a flat ceiling
- Layout diagrams
Your estimate
6 in 12 cathedral ceiling, 4' x 12' sheets2 more than a flat ceiling
Area
To finish it
The slopes are laid out as ceilings and the two gable triangles as one panel, since one triangle's corner offcuts make the other. Sheets come from a layout of every surface.
A vaulted ceiling is two areas a flat ceiling does not have: the sloped planes, which are longer than the room is wide, and the two gable triangles at the ends. At a 6 in 12 pitch the slopes are about 12% larger than the flat ceiling they replace, and the triangles add more on top. The calculator works both out from the span and the pitch, lays every surface out sheet by sheet, and shows the difference against a flat ceiling in the same room.
How the vault is measured
- Rise = half the span x pitch / 12. A 14 ft wide room at 6 in 12 rises 3.5 ft to the ridge.
- Slope length = the hypotenuse of half the span and the rise, about 7.8 ft for that room.
- Ceiling area = 2 x room length x slope length.
- Gables = span x rise for both triangles together, since one triangle cut from a rectangle leaves the other.
Hanging drywall on a vaulted ceiling
- Fasten the slopes as a ceiling, screws no more than 12 in apart along each rafter or truss. The IRC and the Gypsum Association only distinguish walls from ceilings, so ceiling spacing is the conservative reading for a slope.
- Run the sheets across the rafters, starting at the bottom of the slope, so each course rests on the one below while you fasten it.
- Plan the ridge joint. The two slopes meet at an angle that needs flexible or adjustable corner tape rather than a flat seam.
- Avoid a butt seam under the ridge on the gable ends. Finisher Myron Ferguson spans those walls with 16 ft panels instead.
- Rent a drywall lift that tilts, or staging. The top courses are well above a ladder's comfortable reach.
Vaulted work is slower to hang and finish than a flat ceiling. Fixr's cost guide puts the upcharge for cathedral and vaulted ceilings at 10 to 30%. Ask whether a quote includes staging and the angled ridge joint.
Frequently asked questions
Primary references
Manufacturer and industry guidance used to check this article.
- 2024 IRC Table R702.3.5, gypsum board applicationInternational Code Council
- Estimating materials for drywall, Myron R. FergusonFine Homebuilding
- Drywall installation cost, high and vaulted ceilingsFixr
- Application and Finishing of Gypsum Panel Products, GA-216-2010 archiveGypsum Association
Product instructions, tested assemblies and local code take priority over general guidance.