Dimensioning standards

[tim.101799]

This may not be the best place for this thread, but I wanted as much input as possible from the members here. My office is currently looking at changing our drafting standards to be more consistent with the rest of the industry and also make things smoother while working with Revit. Currently the biggest point of contention seems to be dimensioning. I was hoping to hear how you guys out there are dimensioning.

The current office standard (which I do not follow) uses several dimension styles each with different tick marks. For example a dimension with a slash as the tick mark is locating the face of a surface and a filled in dot as a tick mark is locating and objects center line. Currently the firm standard is to dimension Gyp. Bd. Walls to the center line using a filled in dot as the tick mark. Masonry walls are dimensioned to the face using a slash as the tick mark, and any clear dimensions are located to the finish surface also using a dimension with a slash as a tick mark. Also any time a structural grid line is located, the dot tick mark is use to indicate a center line dimension. In AutoCad to do this we have 3 different dimension styles that users have to switch between depending what they are locating. As far as I know Revit would also require multiple dimension styles. As far as locating structural grids, I have looked through 6 sets of drawings for recent projects and not one of my structural consultant’s uses filled in dots as tick marks when locating grids. They all seem to vary between slashes and arrows.

To make things easier in terms of Revit set up, and simple efficiency, I have only been using one dimension style in Revit (slash as a tick mark) and have also stopped locating Gyp. Bd. Walls by their center lines. I have been told on several occasions in the field that contractors hate center line dimensioning anyway. What I have been doing is always dimensioning to the face of walls. If I have 10 parallel walls I would always locate the same face of the walls (see attached) unless of course I need to hold a clear dimension.

I would like to gear what others are doing.

[Scott D Davis]

Revit will dimension a centerline with a couple of conventions: The extension line can be a cneterline linetype rather than solid. Revit can also put the CL symbol on a centerline. This is all from one dimension style.

With that said, there are many different conventions for dimensioning. Masonry dims are always to faces and faces of openings. Some say interior stud wall dimensions should be centerline, while exterior stud walls should be to the face of the structural layer of the wall. I happen to prefer dimensioning to the face of the structure wheter interior or exterior.

This is the important part....except where needed by code for a "clear" dimension, always dimension to the structural core of the wall, NOT the finish. When the contractors are laying out the walls, the finishes don't matter. (and you dont want your framers doing calcs in the field with 5/8" dimensions for drywall)

The convention used for ticks is up to you. Use whatever is the most clear convention for a contractor to read and understand in the field.