Urban planning community | #theplannerlife

# Thread: Building coverage calculation

1. ## Building coverage calculation

When calculating building coverage, what do you use for building area?
A. Roof area
B. Foot print
C. Other - please explain

2. You're just looking for building coverage, right? Not all impervious surfaces? For building coverage allowances we measure by footprint in my city. I wouldn't be surprised if it were different in other jurisdictions, however.

3. Right, just building coverage. I have a client wanting to push the envelope with some cantilevers on the second floor. I have always used building footprint, but the code I'm using doesn't define it. I'll bet they make a text amendment after this project.

4. Right, that would be a problem. I've never had that come up! Good luck with the definition, that could be tricky.

5. Building footprint everywhere I've worked.

6. Originally posted by savemattoon
When calculating building coverage, what do you use for building area?
A. Roof area
B. Foot print
C. Other - please explain
Roof area = impervious surface
footprint = floor area - BUT do you want to measure from the interior or the exterior walls OR from the exterior of the exterior walls?

Some codes I've seen specify this. Most seem to be silent. For some projects that eight inches (masonry concrete block width dimension more or less) can add up.

For a 2,500 square foot building it would come to about 11 square feet.
For a middling big box (40,000 sf plus or minus) it adds about 44 square feet.

I know it doesn't seem like much but I've had some cases where, various reasons, these tiny amounts came into play.

7. ## provide an example please

Originally posted by ursus
You're just looking for building coverage, right? Not all impervious surfaces? For building coverage allowances we measure by footprint in my city. I wouldn't be surprised if it were different in other jurisdictions, however.
I'll be very greatfull if you can send me an example and using meters (m)

8. We use building footprint - but some exceptions to that footprint exist. Such as boxouts over 2.4m above grade - but then we have rules for projections above 2.4m above grade (how much area they can take up and how much they can project out from a building).