Wall Reference Line Side

[Anonymous]

Sorry to have to start a new topic; there are too many already. Many posts seem to skirt this question, but not quite hit it:
Somewhere in here, I think Karl Ottenstein recommended against using reference lines centered in walls because the computer has a hard time figuring out which face is the reference line face. Our office standards locate interior walls by centerline dimensions, and use centerline construction to provide a node to pull dimensions to. Quantity Takeoffs of Interior wall surfaces are in question if we don't know which side of the wall is being used in the calculations.

Wall faces are designated "Reference Line Side" and "Opposite to Reference Line Side" which is ambiguous when walls are created with their Reference Line at the Center. Beam faces are designated "Right" and "Left", with reference to the direction of their Reference Line (Reference Vector, actually).
Anyone know why GS chose to designate wall surfaces using an inherently ambiguous approach rather than the unambiguous approach they chose to use for Beams?

[Steve Jepson]

The only thing that makes it ambiguous is that your using center to center dimensions for walls. Why do you do that?

I think wall dimensions should always be to face of stud/block.

There are several reasons for this. One is that you will have fewer fractions in your dimension chains. Another is that you won't have so many dimensions to places you can't actually hook a tape. For me, face of stud dimensions are more efficient for laying out partitions, both on the floor and on the plates. This is because it is harder to remember the dimensions from the plan when your tying not to forget to place the mark back 1/2 the distance of the wall thickness. This slows me down even more when the thickness of the wall is not shown where you can see it easy. As with a wall schedule or something. When you snap a line for a wall you don't want it on center where you can't see it, you want it at face of stud so you can make the wall straight.
I use centerline dimensions are for everything except walls.

Of all the people using the plans, who is it that would prefer to have center to center dimensions for the walls?

[Anonymous]

Of all the people using the plans, who is it that would prefer to have center to center dimensions for the walls?

I really wanted to talk about the difference between how AC designates faces of walls and faces of beams, rather than debate personal preferences of wall dimensioning. Without going into the many reasons for doing what we do, or the years of experience, internal wrangling and external review supporting them, commercial constructors (several trades) led us to this method.

Now, can we talk about the question I asked?

[Steve Jepson]

I take it that the reason you want the reference line at the center of the walls is for the sake of centerline dimensions.

If you use a composite wall with an invisible centerline you will have the snap point you need at the center of the wall and still maintain the functionality of the reference line for other purposes.

The reason why beams made with the beam tool (there are better choices) have a right and left relative to the direction of reference line arrow is pointing is because beams are almost always dimensioned to the centerline where the reference line would not be functional.
So for beams (made with the beam tool that is) it's better to leave the reference line at the center of the beam and find another way to designate which side is which. This is why the reference line has a directional arrow.

I think you are right on the money to point out the inconsistency here.

Walls could also be designated as right and left relative to which way the reference line arrow is pointing.

[Karl Ottenstein]

Brian wrote:
Somewhere in here, I think Karl Ottenstein recommended against using reference lines centered in walls because the computer has a hard time figuring out which face is the reference line face.

Hi Brian,

Doesn't sound like me, but who knows? 😉 I've recommended against CL ref for walls for some of the reasons that Steve gave in many cases. I know you're talking about interior walls and take-offs and will come back to that after I ramble a bit...

But, I recommend that exterior wall reference lines correspond to the outside face of the bearing structural core skin and align with the outside face (or potentially some offset) of the foundation bearing points below. This make it trivial to change the structure of the wall(s) and have the building footprint not change.

(Log folks use different offsets / bearing positions.)

For similar design (not dimension) flexibility - common/fire walls between units might be done with a center reference line so that as the common wall structure changes, it impacts each unit equally. Etc.

All kinds of other reasons for choosing particular ref line locations... but enough rambling.

With schedules, which is your question, the ref line face is indeed unambiguous for edge (or edge offset) construction methods. For centerline methods, it is unambiguous also ...for the computer... but not so for humans unless you turn off clean-wall-intersections so that you can see the direction in which the reference line points.

When you 'draw' a wall (single fill or composite) with CL construction, the reference line direction arrow follows your direction of clicking. Press F7 (or whatever will toggle 'clean wall intersections' for you) to be able to see the arrows. Or you can just go to On Screen Options > Wall Beam Reference Lines to turn on the reference lines even with intersections cleaned-up.)

If you imagine yourself looking down such a wall along the reference line in the direction pointed to by the arrow, the 'reference line side' is to the left. You can test this just by drawing a few walls with asymmetric composite structures, such as the standard ones with brick facing.

Note that if you use complex profile walls, there is no center line option for placing the wall. You have to actually construct the profile so that the center of the profile is located at the origin of the profile editor window. (The profile editor origin corresponds to where the reference line will be, both horizontally and vertically.) Scheduling here is another story.

Hope that helps,
Karl

[Anonymous]

Thanks for staying with this, Steve.
- Yes. It is or the sake of CL dims, per a deeply considered office standard.
- Good workaround. Another occurs also: always draw interior walls with Ref Line on the the same side (right or left), offset it by 1/2 of the wall thickness. But either is a workaround, as you acknowledge.
- I know what your are saying about beams and CL's, but I don't recall any GS documentation favoring face dimensions for walls and centerline dimensions for beams, and I don't think software has any business limiting those kinds of options. Beams which align at a column face or at the edge of a slab might well be located by dimensions to their faces, and for locating footings and dowel bars in slabs beneath interior CMU walls, CL dims are the ticket. AC acknowledges these valid choices by providing all three Ref Line location possibilities for walls, a reference line direction variable for both walls and beams, and by allowing for ref line offsets for both (too bad they didn't follow through with linetype options for witness lines). IFC uses L & R w/respect to ref vector to designate wall surfaces. It is more than strange that AC walls don't use that same convention. I just wondered if there is a good reason for that.
- by the way and FYI, since it is only interior walls that we dimension to CL, fractional inches are not an issue. We put the walls at even inch locations. Where tighter tolerances are necessary, we occasionally use x/4" dims, as I suspect would be the case from time to time even using face of finish, framing, or masonry dimension points.
@ Karl -
I know how to show wall vectors and determine which side is left and which is right. What I don't know is how to know which the computer picks to list as the Ref. Line side which is the distinction I think it makes for walls when listing face areas (as opposed to a R/L distinction).

[Steve Jepson]

As far as schedules go, it may not make any difference if you put the reference line in the center or at face of stud. The calculation for surface area is correct either way.

[Karl Ottenstein]

Brian wrote:
@ Karl -
I know how to show wall vectors and determine which side is left and which is right. What I don't know is how to know which the computer picks to list as the Ref. Line side which is the distinction I think it makes for walls when listing face areas (as opposed to a R/L distinction).

Ummm.. did you read my entire post? I think I gave you the answer...

Cheers,
Karl

[Anonymous]

@ Karl - Well, I thought I had - twice, but there it is in the next to last paragraph of your reply: The left side. javascript:emoticon(':oops:'). So, thanks for that, and thanks for making me take another look. Is it in any GS documentation anywhere?

@ Steve - Usually, you are right, but when walls intersect at oblique angles, or there is something odd going on at the top and bottom, the two faces can be different sizes. But beyond that, I just like to know what I am doing.
P.S., Am not sure what is up with the image you attached to your last answer here. I am seeing in as a solid black rectangle on my portable (Safari 4.1.3, Mac OS 10.4.11). I hope my "emoticons" above work better javascript:emoticon(':wink:')

[David Maudlin]

Brian wrote:
@ Steve - P.S., Am not sure what is up with the image you attached to your last answer here. I am seeing in as a solid black rectangle on my portable (Safari 4.1.3, Mac OS 10.4.11).

Same here (Safari 5.1.1).

David