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Prodding the fire | Dimension wars, Struct v Arch

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    Prodding the fire | Dimension wars, Struct v Arch

    So this debat came up in my chat room about how dimensioning SHOULD be done in a project. The Struct engineer held that the architect should always move their walls to accomodate a 1/2" precision on their grid lines. To which I replied with these videos:

    http://gibsonhh.info:8081/revit/video/WhoWins.swf
    http://gibsonhh.info:8081/revit/video/WhoWins2.swf

    I always enjoy seeing the differences in how people think when encountered with issues like this. So I ask.. who rules, the Architect or the Structural Engineer? Is there actually a reason a struct plan can not show 1/8" dimensions?

    Enjoy!
    .Carl - Architect, BIM Manager, Father, Husband, Coach, Player, Disc Tosser, Driver... not necessarily in that order.

    Free Revit Chat | Cre8iveThings Blog | Live Architecture! | Past Live Architecture!

    #2
    So what happens if the structural column HAS to be dead center of the wall, and the wall HAS to have a certain clear dimension to the next wall?

    Thank God I do the arch and structural plans. So, all I have to do is coordinate with myself. :laugh:
    Dan

    Comment


      #3
      Originally posted by dzatto View Post
      Thank God I do the arch and structural plans. So, all I have to do is coordinate with myself. :laugh:
      Hows that working out for you??? What happend when you get an RFI, do you consult yourself about what you needed more info on?
      -Alex Cunningham

      Comment


        #4
        Originally posted by revittotd View Post
        So this debat came up in my chat room about how dimensioning SHOULD be done in a project. The Struct engineer held that the architect should always move their walls to accomodate a 1/2" precision on their grid lines. To which I replied with these videos:

        http://gibsonhh.info:8081/revit/video/WhoWins.swf
        http://gibsonhh.info:8081/revit/video/WhoWins2.swf

        I always enjoy seeing the differences in how people think when encountered with issues like this. So I ask.. who rules, the Architect or the Structural Engineer? Is there actually a reason a struct plan can not show 1/8" dimensions?

        Enjoy!
        Sucks to be an architect dont it. What makes your plan look better? Dims should never have rounding. It causes problems in construction if dims dont add up. Make your hallway larger then it needs to be then you wont ever have any problems and no contractor will ever layout walls based off face of finish.
        -Alex Cunningham

        Comment


          #5
          The discusion digressed to "We don't use 1/8" precision because it's not practical in the field; no one will lay out a building to 1/8" " Specifically he mentioned locating columns and pile drivings on the site. So in my never ending quest for construction knowledge, I turned to a local contractor from a large construction company with how they handle site tolerances. This was his response:

          Carl,

          Depends on application but a 1/8" would be max. Depending on if it has a
          bolt pattern for steel associated with it a 1/16" can give you fits on a
          big building. If it is just for concrete with no bolts then 1/8" would
          be OK.

          For dirtwork the industry standard is .10' or 1 1/4" vertical variance
          for subgrade of dirt or rock (this is mainly due to dirtwork not being
          perfectly flat even when rolled with roller or sheepsfoot)

          Thanks,

          Project Manager
          Key Construction Oklahoma, LLC
          .Carl - Architect, BIM Manager, Father, Husband, Coach, Player, Disc Tosser, Driver... not necessarily in that order.

          Free Revit Chat | Cre8iveThings Blog | Live Architecture! | Past Live Architecture!

          Comment


            #6
            Soooo, if you know how to read a tape measure, what's the difference between marking it on the 1/4 or the 1/8? :laugh:
            Dan

            Comment


              #7
              Originally posted by dzatto View Post
              Soooo, if you know how to read a tape measure, what's the difference between marking it on the 1/4 or the 1/8? :laugh:
              Dan, I agree with you on this one.
              I have posted in the past regarding this topic: I am a Builder as well as a Designer, and really have no problem on the building site marking 1233mm as opposed to 1235mm.

              Comment


                #8
                Originally posted by revittotd View Post
                The discusion digressed to "We don't use 1/8" precision because it's not practical in the field; no one will lay out a building to 1/8" " Specifically he mentioned locating columns and pile drivings on the site. So in my never ending quest for construction knowledge, I turned to a local contractor from a large construction company with how they handle site tolerances. This was his response:
                Maybe they are a hack contractor... Thats the only logical explanation i can think of.

                Our guys in the field- when doing Pier locations, ask for decimal feet.... Down to 6 decimal places. Now, thats aside from the point when youre talking about "CAN they lay out that accurately," but to digress back to 1/8 inch... Their argument is just plain absurd. Typical interior walls are covered in dimensions that are down to the 1/8 inch. 4-7/8", for instance. Then you factor in that real masonry walls are also measured down to the 1/8" (down to the 1/16th if you want to get really specific in to dimensional accuracy in a nominal versus actual world) and the fact that interior partitions are generally laid out bu the face or the center of the stud, and not the partition itself, and the truth remains: Without a 1/8" dim somewhere, you are hacking it together, because it isnt right.

                Ive watched guys with tape measures AND robotic total stations all day long, and ive watched leasing agents and lawyers run back over slabs with partitions with tape measures, rechecking. if yuour guys is saying it cant be done, hes not a very good partition sub.
                Aaron "selfish AND petulant" Maller |P A R A L L A X T E A M | Practice Technology Implementation
                @Web | @Twitter | @LinkedIn | @Email

                Comment


                  #9
                  The closest reason I've received to why it's easier is in the case of adding up multiple dimensions on the job site: 1/2" would be much quicker than 1/8" Then again, if you are having to add dimensions on the job site, the architect didn't do a very good job of documenting the project to begin with and you're going to have bigger issues than an 1/8" tolerance.

                  Just to note, I'm not talking about rounding up dimensions here. I'm talking about actually having 1/8" tolerance on your dimensions. The person I was debating with claimed that they will never show 1/8" dimensions (ie: 1/8, 3/8, 5/8, etc) on their plans because it "looks messier" than 1/2"

                  Personally, and from experience, I don't see why Architects and engineers have such a hard time believing that contractors don't/can't use the 1/8" ticks on a tape measure.
                  .Carl - Architect, BIM Manager, Father, Husband, Coach, Player, Disc Tosser, Driver... not necessarily in that order.

                  Free Revit Chat | Cre8iveThings Blog | Live Architecture! | Past Live Architecture!

                  Comment


                    #10
                    Shouldn't be "closing" dimension strings either... have to tell them where the "slop" is, yes there is always "slop". Might as well leave out the dimension that "doesn't matter" as much as the ones that really do. The notion of closing dimensions and worrying about strings adding up is a hold over from reading drawings that have "faked" things on them already.

                    As for dimensioning to a wall or column, the column arrives on site first, walls end up getting placed relative to the structure/envelope. If they don't get that right then everything else is going wrong from there

                    When I hear people say they can't hit a number in the field I can't help but wonder about the steel bridges and that the two piers that were poured 300+ feet apart months earlier...somehow they manage to make those bolt holes line up. Yeah I know...a torch, pry bar and a come-along
                    Last edited by Steve_Stafford; January 5, 2012, 10:18 PM.

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