Autodesk Revit reality check for residential construction: Scott Babin Illinois Tool Works, Building Components Group AB6105-V Using Autodesk Revit for architectural and structural design in the residential single family and multifamily arenaa has not been without its challenges. However, new tools based on the Autodesk family of products make it possible to solve complex roofs and address the surprisingly complex realities of light frame wood construction. Prefabrication and manufacturing have long been a staple of production housing and Revit makes these workflows a reality in 2012. You will see how you can leverage BIM at a time when the economy has builders scrambling for ways to do more with less and streamlinee their processes. Learning Objectives At the end of this class, you will be able to: Check Autodesk Revit residential model for structural accuracy Understand the use of your BIM data in 3rd party applications Identify possible BIM deliverables Utilize structural data in Autodesk Revit architectural models About the Speaker Scott Babin is the BIM Technologies Project Manager for the Global Software division of Illinois Tool Works Building Components Group. Scott has fieldd experiencee in custom cabinetry, custom millwork, framing, estimating, and lumber sales. His primaryry background is 20 years of experience in use of AutoCAD and AutoCAD Architecture in the residential industry. He has many years of experience creating models and construction documents in ACA and tying that information into various estimating software packages and work flows for himself, his team and his clients. He has also done many VisionREZ andd AutoCAD Architecture implementations with clients of ITW across the United States. He has thee ability to implement BIM from the design phase, through construction documents, virtual framing, estimating, and into purchasing using Autodesk and ITW software. Scott is currently moving into Autodesk Revit and is having success combining the old BIM environments with the new. Email: sbabin@itwb bcg.com
Introduction In a residential BIM model there is information that is valuable to trades outside the architecture department. Some of the trades I would like to focus on are manufactures of trusses, prefabricated wall panels, engineered floor systems, andd estimatorss of framing materials. In the world before BIM modeling the trades would simply take an architect s blueprints and redraw the portions of the project they intend to supply too the builder. In the four trades I just mentioned someone would have to recreate the data already provided by the architect. This means the same data was created five times. This repeat of effort greatly increases the chance of human error and it increases delivery time. The old saying of Time is Money is a very true statement in the world of residential construction. In the world of BIM, if the architect takes a little extra effort to ensure the data is correct and then passes that data to the trades the project as a whole benefits. In today s economy, an architect that is savvy enough to catch onto this can greatly increase the value of the servicee he is providing to his builder. Checking Structural Measurements The easiest way for trades to get the data from the architect in a format they can use is for the trade to use software that is compatible with the architect s software. This is not always possible, so another way is to provide the architect a plug-in to the modeling software he is using. A plug-in that extracts the data in a reliable format that is useable for thatt trade. Impact on an architect s workflow should be respected at all times. Minimal impact on an architect s workfloww will also increase the acceptance of this process. The trades we are looking at in this workfloww are manufactures of trusses, prefabricated wall panels, engineered floor systems, and estimators of framing materials. Let s take a look at some of the items in the BIM model that the architect will wantt to check for maximum accuracy. Wall Families The architect should verify all wall components in his families were modeled with accuracy. An example is the stud component of a walll should be setup as true dimensions to contain true building materials. Let s make sure our stud component is a true 3 ½. 2
Wall Heights The levels in Autodesk Revit should be setup at true heights of walls. In this example we will verify the 1 st floor has 9 1-1/8 tall walls on the first floor and 8 1-1/8 tall walls on the second floor. The floor system between the levels is a 16 ijoist as specified by the builder for design of the home. The builder has also specified a ¾ subfloor decking so we need to make sure there is a 16 ¾ floor space in the model to allow the components to fit correctly. Level Settings The trades need to know the difference in levels that are used for modeling vs. levels that are true building stories. Check each level in the model for these settings in the property palette. 3
Roof Families We have been instructed by the builder that there are two roof types in this model. One is the main roof of the home and it will be a 2x4 cord trussed roof. Another is a 2x6 rafter roof system and it willl be over the porch and boxed window. We will check that the roof family properties are correct and create sections to verify and document that the roof has in fact been located in the correct locations. Truss Roof Rafter Roof 4
Check Roof Locations The locations of the roofs should also be checked. Trussed roofs do not sit on top of walls the same way rafter roofs do. You should verify all roofs are in the correct locations by creating sections. It is wise to keep those sections in your project even if you do not use them in the documentation process just as a reference that you have checked the model for accuracy. 5
Door and Window Families The doors and windows of a home have two measurement systems. One is the size of the door or window and the other is the rough opening size needed to actually install the window or door. In Autodesk Revit door and window families there should be rough opening properties and these should be set in coordination with the manufacturer that the builder intends to use. 6
Use of your data in 3rd party applications Once the model is checked for structural accuracy it can be exported to a format useable by trades and the software they use. In a trades work flow prior to adapting to the acceptance of BIM data the trade would have to take a set of construction documents and redraw the information they need prior to applying the trade skill set. In the workflow that includes the acceptance of BIM data the trade would start at the point of the trades skill set. For example there is no need for a truss manufacturer to draw walls because the architect has already performed this task. Another example is that there is no need for an estimator to measure walls because the measurements where placed on the wall objects when the architect modeled them. Let s have a look at some of the trades importing the BIM data and see the point they can start applying the expertise of their trade. Roof Truss Manufacturer Step one; the roof truss manufacturer imports the data. Once the data is in, it needs to be checked for properties that are expected. This roof truss manufacturer would want to doublecheck the architect s structural accuracy. The roof envelope and location will be verified that it is correct. The walls will be checked for structural accuracy and also that they have the correct exposure and load bearing properties. While it is pretty easy for the architect to set a wall exposure to interior or exterior, they cannot easily predict if a wall will be used to bear weight of the truss design prior to design of the trusses. The truss manufacturer should check and set the properties as needed in his software. 7
Once the data is verified and all settings are made, the work of designing and engineering roof trusses can begin. This process has been documented as cutting the time needed to complete a roof truss design in half due to the layout already being completed at the start of the job. Floor Framing Manufacturer BIM data is imported into the floor system manufacturer software just as it was brought into the truss software. All walls and openings are imported and the wall layout is automated. Once this data is in all the floor layout technician has to do is give the data a quick check for proper settings and then begin the task of laying out the floor system. 8
Wall Panel Manufacturer Wall panel software and stick framing software have the same benefits from the BIM data. They also have an additional advantage. Not only can they benefit from the architectural models data, they can also import and utilize the data exported from the roof truss manufacturer and the floor system manufacturer. With the walls and openings imported form the architectural model and the roof and floor systems in place, the tasks of doing in line framing becomes much less difficult. So does the task of applying hardware that connects roof systems to wall system, wall systems to floor systems and so on. 9
Create BIM deliverables BIM deliverables are tangible sets of information that aree given to members of the project. These deliverables can be used by multiple of specific trades. This section will identify several BIM deliverables that can be created from within AutoCAD Architecture and other applications utilizing the BIM data that was originally provided from your Autodesk Revit model. Framed Wall Shop Drawings This is quite useful to the framers building the walls. It shows what material each piece of lumber is, exactly how long to cut them and where they are located in the walls. The information can also be fed to automated saws that will cut the lumber for the framer so he can focus on faster assembly. In this sample there is also a wall specific bill of materials on the sheet listing only the material needed to frame this wall. This was done in AutoCAD Architecture with the help of a 3rd party application that automates creating these sheets. 10
Detailed Anchor Bolt Layouts This layout is useful for the trades that are installing the anchor bolts. This sample was created in AutoCAD Architecture. The framed walls and locations of anchor bolts were done using data imported from the Revit Architectural model. This same layout could be done inside Revit after linking the structural drawings back into Revit. Wall Snapline Location Drawings This layout is useful for the framers who are either installing pre-manufactured wall panels or are building the walls on site. The framer can take this plan and pull a tape measure from the identified start locations. At each measurement location he would pop a caulk line to mark the location of where the wall or wall panel will be installed. This was created in AutoCAD Architecture using data from the Revit architectural model. This same layout could also be done inside Revit after linking the structural drawings back into Revit. 11
Wall Panel Location Drawing This drawing is used to install wall panels. The wall panels by number and openings are noted in schedules. Openings also have rough opening values that were fed into the system by the Revit family rough opening values that we saw in module one. Floor Framing Layout This drawing shows floor framing that was imported into AutoCAD Architecture from an engineered floor system vendor. The vendor used the BIM data form the Revit model to populate his project with the basic geometry needed to perform the task of laying out the floor system. Once done the vendor then passed his floor framing data back and it was used to create this layout that the framer will use to identify floor beams and know the locations where they are meant to be installed. 12
Roof Framing Layouts The roof framing layouts are needed no matter if the roof is a trussed roof or if it is a stick framed roof. Framers need these layouts to help them layout the members in the correct locations. Roof Truss Shop Drawings The shop drawings for roof trusses are created from inside the roof truss engineering software. They are needed on the shop floors for creating the roof trusses on special tables that help position the members of the truss in a specific location prior to pressing the metal plates that permanently hold the members in place. 13
3D DWF with Linked Bill Of Materials There are software packages that extract a bill of material from the models after all framing is done. This data is pushed into a spreadsheet view in a 3D DWF file along with the actual objects in the model. The data is linked to those objects. The linking is a very helpful tool when quantifying material. This deliverable can be given to an estimator so it can be verified that the list of material pumped out of the model is accurate. 3D Framing for Autodesk Quantity Takeoff 3D DWF framing files can also be given to an estimator using Autodesk Quantity Takeoff. This 3D framing is very helpful to an estimator where before he would have done the takeoff based on formulas tied to 3D wall lengths, now he can base his estimating on counts of items which is about 10 to 20% more accurate. At this stage the estimator can also check for structural accuracy to ensure the model was framed using the preferred methods of construction for the company. 14
Microsoft Excel For Bill Of Materials and Estimates Information from BIM models can also be exported to file formats useable by Microsoft Excel. This is one of the most common tools for estimating used today. This can also be used as a platform to convert the data into a format useable by other estimating or back office purchasing software. Use structural data in architectural models Data flowing one way from the architectural model into the truss, floor and wall manufacturer trades is very beneficial to everyone in the project. Even more beneficial is the ability to roundtrip that manufacturing data back into the BIM models. Once the framing and hardware are created, this data can be captured and sent back into the original BIM model. By exporting this data and importing that into blank structural models. In these structural models setup specifically to receive wall framing and wall hardware you can now have a wall framing model that can be inked into any Revit model. This is useful for creating sections and even reporting bill of materials if you choose to do so from Revit. Below are some structural models that were setup to receive data from various manufacturers. 15
Importing wall framing and hardware into Autodesk Revit structural model Here is a model where the wall framing and hardware were imported. You can see that Revit families of the framing and hardware were created upon import and can now be used as any other Revit data can be used in a project. Importing roof trusses into Autodesk Revit structural model In this model I imported roof trusses. If you notice in all the screen shots there is a green cross. This is a useful mark to help line up all the framing should anything get out of line during the manufactures export of the data. 16
Importing floor framing into Autodesk Revit structural modell Here is a screenshot of the floor system imported. Noticee the joist hangers weree also created upon import becausee they were specified by the manufacturer and engineered to hold the weight of the floor at that location. 17
Linking structural models into one Autodesk Revit structural model The benefit of starting with a blank structural model is that you can link all of these into one master structural and create structural documentation. 18
Linking structural models into the architectural Autodesk Revit model Since the manufactured framing systems were imported into individual files, specific framing systems can now be linked into the architectural model. In this example, all we wanted was a section showing the roof trusses along with the typical architectural building section. 19