Square footage calculation discrepancy


MegLee
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Why is my ADU shows 500 sqft TOTAL on the drawing provided by my designer?! What caused this discrepancy?
Designer said that's the software generated numbers and that there're "layers I couldn't see"....! And that nothing he can do!

12'5"W X 38'L =
475  shown on detailed drawing - including exterior walls
 

These 2 numbers have to match in permit application.

Appreciate any feedback!

Thanks!!!

Edited by MegLee
Too wordy
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1 hour ago, MegLee said:

Why is my ADU shows 500 sqft TOTAL on the drawing provided by my designer?! What caused this discrepancy?

 

No clue. See attached, these are "software generated numbers" derived from an OOB factory Chief Architect template file:

1267925622_Screenshot2026-05-15at4_20_26PM.thumb.png.cbcfc58ec086365f53fda23e71d189f4.png

What software is your designer using?

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4 minutes ago, MegLee said:

Here's the Plan which shows the measurements discrepancies. 

 

So I showed that the software generates accurate numbers. This is a question for your designer.

 

2 hours ago, MegLee said:

nothing he can do

 

Sure there is. Change 500 to 472.

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Maybe there's a pony wall about 2" thicker that isn't being displayed on the plan.  Then if the measurements are to the exterior of that wall you would get the discrepancy.  We would need the actual Chief plan file - not a pdf - in order to know exactly.

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Designer's explanation:
"All areas mentioned on the right side of page one are accurate and calculated from exterior walls (including all sheathing). That's how the city calculates and that's how the areas are put in."
"I have done few rounds of check on my end and confident with the answers and the calculation areas I provided. There are specific ways of measuring & I believe what you are inputting doesn't count all the dimensional layers. You do not see those in the drawings and therefore assumptions are made."

Why can he provide formula, numbers to arrive at his conclusion? Measurements on the drawing have to match the total on permit application, right? I saw one which matches exactly. 

And, how often does one see for-sale houses or ADU listed exactly at 2000, 800 or 500 sqft?

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21 minutes ago, MegLee said:


Designer's explanation:
"All areas mentioned on the right side of page one are accurate and calculated from exterior walls (including all sheathing). That's how the city calculates and that's how the areas are put in."
"I have done few rounds of check on my end and confident with the answers and the calculation areas I provided. There are specific ways of measuring & I believe what you are inputting doesn't count all the dimensional layers. You do not see those in the drawings and therefore assumptions are made."

Why can he provide formula, numbers to arrive at his conclusion? Measurements on the drawing have to match the total on permit application, right? I saw one which matches exactly. 

And, how often does one see for-sale houses or ADU listed exactly at 2000, 800 or 500 sqft?

 

Discussion between you and your designer.  Explain your concerns and have him demonstrate how he calculated these areas.  That can be done graphically with a polyline that shows the actual area.  He should be able to do that quickly.

 

 

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something is missing for information. For the ADU, using the measurements on the plan, which look to go to the framing, it is 722 sq ft. his plan says 750. The perimeter is 137 ft, so the ft "missing around the permiter" is 750-722=28 sq ft divided by 137 ft, which is 0.2ft or 2.4" all the way around. maybe that is the cladding and sheathing, but if it is I'm not sure what it would be, you would have to see the rest of the plans

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