How to Measure Cathedral Ceilings
A cathedral ceiling has sloping walls that rise to a peak, giving the room extra height and a feeling of spaciousness. Decorating, insulating and framing a cathedral ceiling can be slightly more complicated than performing the same procedures on a flat ceiling, in part because cathedral ceilings are a bit harder to measure. However, all you need is some middle-school geometry. Drawing a diagram of the room as you work can help you visualize the various surfaces you are measuring in basic geometrical terms.
Draw a simple diagram of the room on a piece of paper, with a rectangle representing the room itself and a triangle on top of it representing the cathedral ceiling. Draw a line straight down from the peak of the triangle to the top of the square, dividing the ceiling triangle into two right triangles.
Measure the distance from one side wall of the room to the point in the middle of the room directly under the ceiling's peak. Record the measurement on the diagram as the base of one of the two right triangles. Repeat the process on the other side of the room to find the base of the other right triangle, in case the two sides aren't even.
Measure the height of the walls where the ceiling begins to slope. Measure the height of the ceiling at its tallest point. Subtract the height of the walls from the height at the top of the peak to find the height of the triangle on the diagram. Write this height beside the line on the diagram dividing the ceiling into two triangles.
Use the Pythagorean theorem -- A squared + B squared = C squared -- to find the length of the sloping ceiling panels. Square the base of one triangle and the height of the triangle, add them together, and find the square root of the sum. This gives you the length of the hypotenuse of the triangle, in this case the sloping panel. Repeat with the other right triangle to find the length of the other sloping panel.
Measure the length of the room at floor level. Multiply this measurement with the hypotenuse of one triangle to find the square footage of that side of the ceiling. Repeat the process on the other side to find its square footage. Record the results.
Add the bases of the two right triangles to find the total width of the room. Multiply the sum by the height of the triangles, then divide the product by 2. This gives you the square footage of each of the triangular segments of wall that meet the sloped ceiling, above the square walls of the room.
Add the square footage of the two sides of the ceiling and the two triangular wall segments to get the total square footage of the cathedral ceiling.
- Omit the triangular wall segments if you only need the measurement of the sloped ceiling itself.
Stephanie Mitchell is a professional writer who has authored websites and articles for real estate agents, self-help coaches and casting directors. Mitchell also regularly edits websites, business correspondence, resumes and full-length manuscripts. She graduated from Syracuse University in 2007 with a Bachelor of Fine Arts in musical theater.