Saturday, April 13, 2013

Floor Perimeter

When you examine the properties of a floor you'll find Perimeter. Somebody decided perimeter shouldn't be available to tags so we can't tag a floor but we can see it in schedule (no, can't tag it in 2014 either).

If you alter a floor sketch to define an opening for something like for a stair or a mechanical chase, it alters the perimeter calculation. If you use either a Shaft Opening or Opening by Face it doesn't alter the perimeter value. Floor A is untouched, B is altered within the sketch and C has two openings one of each type. You'll see in the schedule that perimeter is not altered except where the floor sketch is changed to create the opening.


The moral of the story? If you'd like to be able to use the floor slab perimeter value then don't edit the floor sketch to create openings.

7 comments:

Tim Funston said...

INTERESTING!! - Just had a question about calculating Perimeter. Thanks for the simple and brief explanation.

Martí Broquetas said...

Interesting, but actually, in terms of getting accurate quantities (for construction) the perimeter I need is the one that includes de perimeter of the holes (to calculate slab edge formowork in case of concrete slabs).
My doubt is, how can I (easily and automatically) get a count of the openings area to be able to get the gross area and the net area of the floor slab? Any workaround? Any add'in like the WallOpeneningArea?
Thank you!

Steve said...

If you want the total perimeter for forming then editing the sketch reports what you want.

Item B reports the perimeter of the floor including the hole's perimeter. The perimeter of A is 104 FT. The perimeter of the hole in B is 27 FT The total reported perimeter for B is 131 FT.

If you want to count openings you can use a family to cut the holes instead. Just keep in mind that it won't increase the perimeter of the floor either, like the shaft opening or Opening by Face.

Martí Broquetas said...

Thanks Steve, the problem is, as far as we quantify projects in Barcelona, that I would need both the perimeter that I would get bu editing profile, and the opening area count that I would get using a family to cut holes. THIS is how project estimates are done here, all holes below 4sqm are included in the calculation of the area, holes between 4 and 8 sqm are counted only 50% and holes above 8sqm are discounted. It's the real construction industry standard here, and I am getting crazy to get an efficient way to do this (other than modeling a slab family called "slab hole" and hiding it).
Someone with down to construction site experience should advice autodesk for enw realeases.

Or I guess we will all end up using estimating programs instead.

Thank anyways

Steve said...

There is no single button to press that will give you an estimate in Revit. It takes multiple reports of information to arrive at a price.

A floor schedule will give you area and perimeter values. Opening families will give you another way to examine the data. Together they can get you closer than manual takeoffs.

If you have experience with the API or can hire someone that does you might be able to have more data extracted with less effort when you run the app. It will take effort (time and money) to develop and application too.

Martí Broquetas said...

Thanks Steve, I know, I know, in no way a presupose I can click the "estimate" button. But it just seems silly that a bIm tool can't extract by itself with it's factory settings simple geometric data like perimeter + void area.
There's been developments in Spain with tools like Medit or MagicBC3 that allow to link the revit model to our standard estimating programs, and of course they can count the openings you manually do editing profile.
I was just wondering if someone had found a cheaper way than buying those tools.
THanks!

Steve said...

The tools we have were developed based on the information they gathered at the time and the experience of the product designers. Most likely the specific method you are are accustomed too just didn't get communicated to them.

It's not that they lack the ability to make Revit to do things we want. We outnumber them, and we want a lot! :)