Determining Board Feet of Lumber

[Markvl]

As we all know when we draw walls, floors (slabs) and roofs the component portion of each object representing lumber is a monolithic object that in itself can only give area and volume.  How does one determine board feet or the number of joists, studs or rafters required from the data we can retrieve from these objects.  A formula of course.  Would anyone care to share how that is done?  I haven't figured it out yet.  I'd like to get estimating materials worked out more for the company I work for using the models we create.  More BIM!

 

Thanks.

[CipesDesign]

You could probably do this in a fairly simple spread sheet. The math is pretty simple. Using the attached table, all you would need to know is the total lineal footage of each size of lumber... 

[Markvl]

Math is not a strong suite @CipesDesign  How do I apply those board foot numbers to a slab for instance.  We'll use a space that is 10ftx10ft using 2x10's

[Guest Wes Gardner]

Do you want quantity of 2xs or BF of lumber? We know that one BF = foot x foot x inch but that isn't typically how 2xs are sold.

[Markvl]

Hi @Wes Gardnerit would be quantity of 2x's not BF.

[JackBuilt]

In theory, if you could get the parameters correct for the wall framer tool, the tool should be able to generate a generic takeoff.  Of course then you have to account for the idiosyncrasies of the particularly framing crew involved.  Nevertheless if you could template this well it should be a good budgetary ball-parker.  Wes has posted some pretty impressive framing tool models in the past - if you had data for all the components it should be pretty accurate.  I have not had great success with the framing tool but I have modeled framing for a more visual takeoff.

 

Edited December 10, 2020 by Inspectorjack

[taoist]

You may frame the floor and do takeoffs from that.

Floor frame tool has built in worksheets

Or do the math based on joist spacing etc..

If done this way you would need to account for joists that are not part of the O.C. framing.

 

 

[Markvl]

@Inspectorjack I hear ya but when you're doing a 50+ unit multistorey apartment building, using the framing tool gets long and tedious.

[JackBuilt]

33 minutes ago, Markvl said:

@Inspectorjack I hear ya but when you're doing a 50+ unit multistorey apartment building, using the framing tool gets long and tedious.

Understood.  I manually modeled that after few tweaks with the framing tool made me think in that case I could model it manually faster.  A larger project on the other increases the value in figuring out how to adapt wall styles to generate reasonable framing takeoff.   Put an underling on it if there is one to do so.

[CipesDesign]

Well, in the old days when I was building a lot, the very nice and knowledgeable people at the lumber yard did takes-offs from plans, for free... Additionally, for old-style 16" O.C. Wall Framing, we used to use 1 stud per foot, which was always a remarkably close estimate and accounted for kings and trimmers at openings and corner studs, etc. The length of the plates is easy, it's the perimeter times 3, etc. etc.

 

Maybe you should make a bit of effort with math?? It's really not that hard. But in my mind it really comes down to a fundamental dichotomy: some people understand ALGEBRAIC type math, while others hate algebra and understand GEOMETRIC type math better. I am of the latter school, being quite a visual thinker. But you can use either one to solve the same problem(s), and even cooler, you can use one to prove the other 😉 For me the teachers I had, with one notably exception, could never get me to understand. So there's that as well...