Here?s my current thinking for American platform framing ?
In an attempt to hold true to the ?BIM/model it as if it were real? scenario, I?m trying something a bit different than my prior models.
I will use the methodology of setting the sub-floor of the first floor at Z = 0?-0? - the rationale being I don?t know what finishes (and their thicknesses) will be selected at the beginning of a project. The same will be true for any subsequent floors, i.e. Z = elevation of subfloor. All other elevational information will be worked ?up? and ?down? from there. I will model the subfloor on the First Floor Floor System layer but the finished floor material will be modeled on the First Floor layer (see Layer Settings below) This system requires that the ?Z? of floor layers be set at the underside of the floor framing system plus the thickness of subfloor and COULD require adjustment of the ?Z? height of the layer if the framing system changes from what was first chosen ? like going from 2x10?s to 2x12?s...
The walls on the first floor will have the following height? Z = 0?-0? and delta Z = top of top plate. ( See Layer Settings below) and will be modeled to stop there. The walls will be set up such that face-of-stud = face-of-foundation wall below (a typical detail I use?)
The second floor floor system will be modeled such that it contains the second floor floor slab and any joists and beams required (also true for the first floor floor system) ? in plan view, the slab will be modeled to stop just behind the sheathing ?in plane? with the STUDS below. This will provide the correct ?offset? for the Floor Framer. Additionally, I will create a wall style called ?Band Filler? that is as thick as the sheathing and exterior cladding combined. This will provide me with the ability to model things correctly and hopefully get wall area take-offs that are fairly accurate.
Ceilings will be modeled on the floor layer they are associated with ? i.e. the first floor ceiling will be on the First Floor layer ? along with any framing to deal with tray, vaulted, barrel, etc. ceiling forms.
The second floor walls will stack on top of the second floor floor system (just like the real thing?) and will stop at their top plate.
The Attic?in keeping with this methodology, I should have an Attic Layer containing the framing and any flooring required.
Last time I modeled cathedral ceiling or double-height spaces I had a moment of concern as I couldn?t get windows that are ?high? or that are up in the triangular portion of a gable-end wall to show correctly in plan. My solution was to model that ?triangle? on the Attic layer (along with its window(s)?
The Roof will be modeled on a Roof Layer
Layers for a two-storey house -
First Floor Floor System
Second Floor Floor System
Taking a look at what?s below - Footings Layer ?Z? is set to accommodate the majority of the footings ? stepped footings and smaller pier footings can just be moved up as required ? (I use a Wall Style to model footings so I can easily run reports for take-offs)
Foundation Layer ? ?Z? is set to top-of-footing and delta ?Z? is set to top of block (or top of poured-in-place concrete), this retains the ability to set the wall height so it is linked to delta Z. I also place the Sill Plate here (and need to allow for the thickness of it...)
BTW - I have NOT tried this methodology across an entire set of drawings, so as yet, I have no idea where it will break down...
Any comments are always welcome