Roof Assembly With Solid or Laminated Wood Decking

[wojocad]

I'm committed to using whatever Revit can provide in the matter of being able to obtain an accounting of the building materials in a model at any time. My current roof assembly consists of 2 1/2" solid wood decking under a furred cavity space consisting of 2x rafter material and rigid insulation under plywood sheathing under wood shake roofing. There does not seem to be an menu option for wood decking. Is there a way to add properly dimensioned solid or laminated wood decking to the component list for creating new roof assemblies? Can it also (without an add-on estimating software) account for either lineal footage or of square footage of that material in a material take-off?

[Alfredo Medina]

The roof type must have all its layers properly defined. Then, the material take off schedule can give you areas and/or volumes of the materials, based on their definitions. To calculate linear quantities, you need to add calculated values to the schedule; you might also need to add new parameters in case you need them later as part of formulas for the calculated values.

[wojocad]

OK... can anybody point me to a tutorial that tells me the steps to accomplish it?

[SkiSouth]

The layers such as the decking (finish1), the air space (membrane),rafter/insulation (structure),plywood, (structure), felts,(structure), shingles (finish 2), are all added under roof properties -> edit. Just duplicate a generic roof, rename it, then edit it by inserting the layers you need. Rename and assign the layers their function, moving them above, below or inside of the core of the roof. This will create the roof you need. As far as scheduling materials via formuli, that can be involved. Its not the most difficult thing to deal with but be ready to deal with the WTF factor (via stages of revit experience). I'll see if I can find a few threads for you.

One link HERE (http://forums.augi.com/showthread.php?t=118587&highlight=schedule+formula) Do an advanced search on Revit forums for "schedule formula" and you'll find some reading material...:)

[wojocad]

Yeah... I already did that... Except I called the decking layer "Structure - Dimension Lumber" instead of a finish layer. It seems there's a lot missing in Revit that you can spend a hell of a lot of time creating for yourself... if you can find documentation on how to add to the out of the box libraries. Wood decking isn't exactly a new rocket science material. I understand that the Revit MEP package didn't include electrical conduit families. If I was an electrical contractor working on a large commercial project, I imagine that's the one item he'd need to model most to look for conflicts with structure and HVAC.

I do mostly residential projects, so it would be nice to be able to keep track of how much structural decking there is in a big residential project. I plan to learn how to do a material take-off when I get this thing finished. Other than that and possibly a Energy Use and Green Building Analysis, there's really not much need to BIM model a residential HVAC system or electrical or plumbing systems.

I'd appreciate it if you could find me a document on adding something to the building parts library.

[patricks]

Yeah... I already did that... Except I called the decking layer "Structure - Dimension Lumber" instead of a finish layer. It seems there's a lot missing in Revit that you can spend a hell of a lot of time creating for yourself... if you can find documentation on how to add to the out of the box libraries. Wood decking isn't exactly a new rocket science material. I understand that the Revit MEP package didn't include electrical conduit families. If I was an electrical contractor working on a large commercial project, I imagine that's the one item he'd need to model most to look for conflicts with structure and HVAC.

I do mostly residential projects, so it would be nice to be able to keep track of how much structural decking there is in a big residential project. I plan to learn how to do a material take-off when I get this thing finished. Other than that and possibly a Energy Use and Green Building Analysis, there's really not much need to BIM model a residential HVAC system or electrical or plumbing systems.

I'd appreciate it if you could find me a document on adding something to the building parts library.

What you're describing isn't "missing" from Revit. It's not something you add, either. It's just how you define the roof assembly. Whether you consider your decking layer to be part of the structural core, or the bottom finished layer, is entirely up to you.

Things like walls and roofs and floors are known as "system" families. They are not saved out anywhere as RFA family files. You just create them in a project and define the various layers to be the various materials you need.

Depending on how layers might need to join with other layers in section views, I might make your roof with the 2.5" deck and the rafter material as separate layers with separate materials, but both within the structural core. Then the plywood deck is set to Sheathing, and finally the wood shake material on top set to Finish 1.

Have you completed any of Revit's tutorials on making floors, walls, or roofs? If not I would suggesting taking a look at them.

BTW scheduling and quantifying the decking, sheathing, and shingles should be relatively easy. It's simply a matter of getting the reported area (or volume if needed) for each material using the material takeoff tools in Revit. The rafter material will be a little more involved. Since that's stick material with a defined spacing, you would have to use calculated values to convert an area into a linear foot number based upon the number of linear feet of furring you have within a given area.