As of today, there are still problems with the quantities the interactive schedules generate. If you model your footings and foundation walls as walls, and schedule the volumes, they will not be the true volume you can verify by hand, and they will not match the volume you will get if you convert them to morphs and schedule those morph volumes.
The morph volumes will be the more accurate quantity. This is not a mistake in the calculations the program makes, it is because of how the program understands the wall intersects/clean up.
Does it consider the total length of the wall measured on the outside or to the reference line? Does is alternate the lap of the walls at corners or does it miter them. Things like that.
Per my tests, if you really want to know the true volume, select the footings and foundation walls and copy them off to the side. Then convert them to morphs and schedule the morphs, not the walls.
This is especially true when the corners are not 90 deg. As in the case of a bump out with 45 deg walls for something. The way the walls clean up can be seen when you select them.
You will also find the there is a discrepancy between what the lable says the length is, the dimension on the plan, and the length showing in the schedule.
It all boils down to the fact that you must be very careful about verifying the quantities in the interactive schedules. Some of this can be controlled by how you model, what you model something as, and the specific perameters of the schedule.
I am not sure it is actually possible to generate an accurate schedule for things that should be very reliable.
I posted some stuff recently about here:
http://archicad-talk.graphisoft.com/viewtopic.php?t=51852
ArchiCAD 25 7000 USA - Windows 10 Pro 64x - Dell 7720 64 GB 2400MHz ECC - Xeon E3 1535M v6 4.20GHz - (2) 1TB M.2 PCIe Class 50 SSD's - 17.3" UHD IPS (3840x2160) - Nvidia Quadro P5000 16GB GDDR5 - Maxwell Studio/Render 5.2.1.49- Multilight 2 - Adobe Acrobat Pro - ArchiCAD 6 -25
