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View Full Version : 2012 What's the best way to generate quantity and cost estimates?



patricks
2011-10-18, 03:12 PM
We're trying to take our Revit models to the next level for clients who are willing to pay additional fee for this service. This will likely evolve into something like integrated project delivery.

To make this happen we're trying to set up schedules (either component schedules or material takeoff schedules) that will help generate cost estimates from the Revit model. The issue we're running into is getting cost information from wall sweeps.

The attached Revit model shows something we might do on a typical project. There's a metal stud wall with EIFS, and a brick wainscot. Then up top there's an EIFS cornice, and then the roof above. I can get a wall schedule to read the walls (and account for the presence of the door), and I can get a separate schedule to read the hosted EIFS cornice sweep.

The problem is the brick sweeps as part of the wall type. There has GOT to be a way to get some quantity and cost information out of there. Sure there are workarounds, but it seems like those get away from the functions Revit has designed into it for this type of assembly. Sure I could do the brick as separate hosted sweeps, but that seems counterproductive since Revit's wall types have provisions for building the sweep into the wall type. In most cases that's a better way to do it, from a documentation and revisions standpoint.

The other issue is the duplication of EIFS material at the top of the wall, behind the cornice sweep. In reality the EIFS on the wall would stop at the base of the cornice, and continue up some additional angled framing. How can we account for that in schedules?

This is really our first dealing with quantity and material cost and takeoffs from a Revit model, so if anyone experienced with this kind of thing could lend their thoughts, it would be greatly appreciated.

SamuelAB
2011-10-18, 08:08 PM
Not really an answer, but you may want to take a look at the book "BIM construction Management" by Brad Hardin. He talks about the advanced functions of cost estimating with other software.

smashta
2011-10-19, 03:18 PM
Hi,
in fact if you are serious about cost estimation you can not do it inside revit. the problem lies within the fact that revit account for materials and the work associated with them .... example, laying brick might require the brick be washed before laying it, that activity cost money ... concrete form work require materials and installation ... revit o not have any idea about that ....
solutions:
find something that integrates with revit to read materials B.O.Q ...
build your own solution ....

hope that helps ...

RobG
2011-10-19, 04:15 PM
this is one of the reasons we don't do our sweeps in the wall type itself. It creates issues down the road. As for the EIFS at the top. You'd have to deal with the unlocking of the material at the top to bring it down where you want. given the example provided, you'd probably wind up having to modify the EIFS sweep a bit to make up for that change.

As for the rest of the question, it's a time consuming process to set up for Quantity take off. Sheathing items (say drywall or plywood) can be done using area of material/32 (32sqft to a sheet) would give you an estimate on number of sheets, but items like studs would be length of wall / 16" (for 16" spacing) plus you'd want to add things like the sole plate and the double top plate (conditional parameter, length of wall/8' * 3) the downside is you don't get the quantity for things like double studs at openings and the header. You could however get your stud take off from using the framing add-on also.

Things like brick can be done either area or volume, concrete is an easy volume one.

Add to all this.... this is why it's important to setup materials to differentiate between 1/2" drywall and 5/8" drywall, or 4" studs vs 6" vs 8" studs.

I can say i've done it, i've got schedules made on a residential level, tested it, and found it quite accurate, it's time consuming on the front end, and if well done would work for larger projects just as well. The downside is that materials don't know what level their on, so if you wanted quantity take off for say just a basement refinish (which i just did last week for my own basement) you wind up having to add a parameter to the walls/floors to give it a name that can be used in the quantity take off scheduling.

a lot of work, but worth it in my opinion!

Cost estimation : you can get yourself a cost on material, but it might be harder to get an installation cost done. Unless you get yourself with a contractor you know all his prices on installation above and beyond materials, then it would be hard! We gave our contractor our wall types, and he's come up with prices that we can use in our wall types that include material and installation fees. Some things were harder. As for washing brick like smashta points out, i don't think i've ever seen that done!

Given time, Revit can do a LOT of cost estimating without using a third party addon. Just gotta be persistent!

andrewg
2011-10-19, 05:44 PM
Try the 30 day free trial of Autodesk Quantity Takeoff. It'll take a direct export from Revit.