Expert: Dan Griffin - 12/24/2009

Question
Our company recently uploaded the planswift estimating program. Although it is helpful in drywall and metal framing estimating, it does not have calculations to estimate acoustic ceiling grid material.Wall angle and tile are relatively simple to estimate but, the formulas are written in "pasquel language". Can you tell me the formulas for figuring: 12' mains, 4' t's and 2' t's?
When digitizing a room, the room may not be square or rectangular in nature but have offsets or L shapes. The program figures every room into squard footage.
Ive contacted Armstrong and the basic formulas theve giv are:

                 12' mains = sf / oc spacing / length of component
             and basically the same formula will give me the other material.Is this accurate or correct for estimating grid material?

Answer
Jeff, there many ways to get there. It really depends on how large the work is that you considering and how detailed a take off you need.  Most contractors figure total square footage and use multipliers to get the gross quatities of materials, always figuring generously.  Left overs can always go on to another job.  Most commercial supply houses can get you close if you give them the square footage.  The only way to ever get down  to a really tight estimate is a room by room take off, and even then you may end up with too much material, as fall offs can be used in larger jobs, though the labor may make it easier to supply new throughout without having the fellas dig through the scrap.  When I have one or two rooms or a strange color grid, I might get tighter, but in general the grid cost is minimal compared to tile/insulation/labor.

If you want a detailed take off per room, you might like this calculator:
http://www.csgnetwork.com/dropceilingcalc.html
but you will drive yourself nuts entering data for a large project.

Here is another one that requires more details than I like to input, but is great for one or two rooms:
http://www.acousticalspecialties.com/ceilings/grid-estimator.php

If you really want to mess with odd shaped rooms, this one works:
http://www.acpideas.com/estimator.cfm?XlinkID=1&XRequireOnce=YES&CFID=2190933&CF...
but, again, much more input than I chose to use.

This is the one I use, this formula will get you close on mains and cross tees, you already needed to calculate gross square footage for tile.  I use 5-10 percent waste on a large job, especially on tile and wall angle.
sqft x .0209 = mains
mains x 6 = # of 4' tee's
mains x 6 = # of 2' tee's
mains x 3 = # of wire hangs
length in inches from structure to ceiling + 16" for wraps x wire hangs / 144 = number of 12' wires.
This does not give you wall angle/pop rivets/tile.  Wall angle is unique to each room.

I hope this gives you the information you require.