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    NOOB roof questions

    1. I seem to have lost the link between roof boundary(ies) and selected walls, because truss or rafter is no longer available in the roof's instance properties. How do i get that linkage back? (EDIT when I select the boundary lines, "extend into wall (to core)" is checked. END EDIT)

    2. I thought I understood the difference between setting the roof to truss or rafter:

    truss = bottom of roof core intersects outside of wall core
    rafter = bottom of roof core intersects inside of wall core

    If my understanding is correct, I've attached two drawings showing something odd: My bottom of roof core is the underside of insulation panel, but the intersection point is the underside of the entire roof assembly. Moving any or all of the roof layers in and out of the core boundary does note change the intersection point. Changing any or all of the roof layers function does not change the intersection point. Is this correct behavior? It doesn't seem logical.
    Attached Files
    Last edited by lost again again; December 1, 2011, 08:03 PM. Reason: added addtional information

    #2
    Can you post screen caps of you wall/roof structure layers? They don't seem to make sense based on your image unless Im reading it wrong.

    Comment


      #3
      Originally posted by Eliot Black View Post
      Can you post screen caps of you wall/roof structure layers? They don't seem to make sense based on your image unless Im reading it wrong.
      Eliot: Since I posted, I've tried many different combinations of moving things in and out of the core boundary and ended up completely removing assembly layers to get what I needed on paper for my consultant. I think the walls and roofs used when I created my first attachments match the assembly descriptions attached here. Thanks for looking at them.

      Can you elaborate on what doesn't make sense: my description of the layers or the program's behavior?
      Attached Files

      Comment


        #4
        Normally the core of the wall is going to be the structure of the wall, and the exterior and interior sides are going to finishes and layers related to finishes. Take a look at the functions of each later 1-5 from structure to finish 1 and 2, these are very very important to how walls join up and which layers cut through others. The smaller numbers will cut through larger numbers, so structure will always cut through finishes. In your case making insulation function 1-structure will lead to unwanted results. Sort this our and I think you will get closer to what you wanted orginally.

        Comment


          #5
          I'm certainly no expert at the assembly layer functions and will investigate further. I had them correct originally but had to start experimenting because the real problem I'm having is the connection of the roof to the wall.

          Isn't the roof's core (regardless of whatever layers it contains or their material descriptions) supposed to be the relevant line when it is placed in relation to the base level? My roof is being set by the entire assembly, finishes and all.

          Comment


            #6
            I believe, and someone more knowledgeable can jump in, the roof truss/rafter is determined by the intersection of the bottom of the roof (core to interior/exterior is ignored) and the core of the wall (when embed to core is used, otherwise the entire wall dictates) and the level association. See images below to see if that helps. The core of the wall is gray, the core of the roof is blue. Adding an additional interior layer to the roof just moves the whole roof up.
            truss.JPGrafter.JPGwall.JPG

            Comment


              #7
              Eliot's diagrams and explanation of the function of the core for setting the location of the roof is correct.

              For trusses, the outside edge of the core is the intersection of the underside of the top chord and the underside of the bottom chord of the roof truss. For rafters, the underside of the rafter aligns with the inside face of the core.

              Cheers
              Ian Kidston
              http://allextensions.com.au

              Comment


                #8
                Originally posted by Eliot Black View Post
                Adding an additional interior layer to the roof just moves the whole roof up.
                [ATTACH=CONFIG]5533[/ATTACH][ATTACH=CONFIG]5534[/ATTACH][ATTACH=CONFIG]5535[/ATTACH]
                Eliot: I think you're right about the whole roof shifting when a finish is added below the roof core. That seems wrong, both from a construction standpoint and just logically. You can't support a rafter or a truss with a finish material!

                Is the correct process to use a roof only for the structure and layers above the structure, then use ceilings and soffits for anything below the structure on the inside and outside? I haven't put many ceilings in yet and so far they've all been flat and not related to the roof structure. I just tried to create a sloping ceiling (e.g. decking at the underside of rafters) and the process is not very intuitive. I created it using the same slope as the roof, then manually moved it up. If I lock it to the underside of the roof will it cause problems later when the roof changes?

                Bonus question: what is the use of a "basic ceiling"? It looks like a line in section. The help menu doesn't describe why they're included in the program.

                Comment


                  #9
                  Originally posted by lost again again View Post
                  Eliot: I think you're right about the whole roof shifting when a finish is added below the roof core. That seems wrong, both from a construction standpoint and just logically. You can't support a rafter or a truss with a finish material!

                  Is the correct process to use a roof only for the structure and layers above the structure, then use ceilings and soffits for anything below the structure on the inside and outside? I haven't put many ceilings in yet and so far they've all been flat and not related to the roof structure. I just tried to create a sloping ceiling (e.g. decking at the underside of rafters) and the process is not very intuitive. I created it using the same slope as the roof, then manually moved it up. If I lock it to the underside of the roof will it cause problems later when the roof changes?

                  Bonus question: what is the use of a "basic ceiling"? It looks like a line in section. The help menu doesn't describe why they're included in the program.
                  For a number of reasons, I never show a layer under the core structures in a roof.

                  If I have a vaulted ceiling where it will be lined under, I model the lining as a separate element entirely. Adding a layer under seems like an appropriate way to do it except that the lining will never be continuous from the inside of the building to the eaves. As you quite right note, the additional layer will push the roof up, which is clearly incorrect.

                  If I was designing a roof with a standard flat ceiling, the lining is attached to the ceiling joist or the underside of the bottom chord of the roof truss. In both these instances, I would use the ceiling tool to create the lining. With a ceiling in place one can host lights and other ceiling based families.

                  It is however a pity that the ceiling tool is so basic and that one cannot easily created vaulted ceilings and the like.
                  Last edited by Ian.Kidston; December 2, 2011, 10:59 AM.
                  Ian Kidston
                  http://allextensions.com.au

                  Comment


                    #10
                    Not to mention, if you create your ceiling layer as part of the roof, any ceiling based families (such as light fixtures) won't work. There needs to be a ceiling there to host them.
                    Dan

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