Estimating Multiple Ceiling Heights

Multiple Ceiling Heights on a Floor

The BidMagic estimating software uses just one ceiling height on each story. When a story has more than one ceiling height in different rooms, you can handle it in one of several ways.

Remodeling Projects

If the project is handled on a 'room by room' basis, simply enter the ceiling height used in each room into the appropriate Room card. BidMagic will automatically calculate the correct quantities of wallboard for the project.

HINT: Some projects with many different ceiling heights are best treated as a remodeling project, even if they could otherwise be considered new construction, an addition or a gut/rehab.

Dropped Ceilings

If only a few rooms such as halls and bathrooms have a reduced ceiling height, enter the ceiling height for the 'main' rooms on the Basic Dimensions card. If the dropped ceilings are supported on independent ceiling framing, enter their area into the Miscellaneous Dimensions card.
By using the full ceiling height, you will slightly overestimate the area of wallboard on interior walls. Most people ignore this, but if you'd like the greatest accuracy, compute the amount of 'missing' wall above the dropped ceilings, and subtract it from Gross Interior Wall Area on the Finish Dimensions card.

Using Weighted Averages

A project that has a mixture of different ceiling heights due to mixed roof heights or a split-level structure is best handled with the use of weighted averages for ceiling height.

HINT: Weighted averages are easily computed in a spreadsheet program on your computer!

To calculate the weighted average, follow these steps:

1. Multiply each section of floor area by its ceiling height. EXAMPLE: if you have 500 sq. ft of 8 ft ceilings, 100 sq ft of 10 ft ceilings and 200 sq ft of 12 ft ceilings, the numbers would be (500 x 8)=4000, (100 x 10) =1000 and (200 x 12)=2400 respectively.
2. Add up each of the numbers from step one. EXAMPLE: Add together 4000+1000+2400, for a sum of 7400.
3. Add the areas to get a total area. EXAMPLE: Add together 500+100+200 to get 800 square feet of total area.
4. Divide the sum from step two by the total area from step three to get a weighted average. EXAMPLE: Divide 7400 by 800 to get an average ceiling height of 9.25 feet.