Changing Values according to results of dropdown menu.

Hey Excellers

I wonder if this will work...

I have attached my spreadsheet...

The columns N and Q all have dropdown menu for location...
The results are as follows:

FLOOR
CEILING
END WALL
END WALL (Door)
RIGHT WALL
LEFT WALL

In each one of those boxes there is a field called "Area"
In column S there are surfaces that correspond to the above results...
And in column T is an "Area" field which have formulas in to calculate the areas of these surfaces taken from the room dimensions at the top of column C.

What i want to do is... If any of the dropdowns are set to CEILING (N4). Then the "Area" of that box will be subtracted from the number in in T11, which is the area of the CEILING. If there was 3 basstraps on the ceiling then there would be 3 different values that would all need to be subtracted from T11. I need to do the same for all of these surfaces...

Is this even possible or am i Insane???

John

So are you wanting to replace the T11 formula?

If so, perhaps:

=C4*C5-IF(N5=$S11,$N$8,0)-SUM($T$18:$T$20)

and you can add similar functionality to other surface values in column T