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Drawing up the Details of Classroom AV Systems - Part 3
by Mike Tomei, Tomei AV Consulting
This is the third article in a monthly series focusing on the design and construction process surrounding audiovisual systems in higher education classrooms. In the last installment, I described the administrative and schematic design phases for classroom audiovisual installation projects, as well as the resulting reports and documents. Once those schematic design deliverables have been approved by the client, the next step is the design development phase.
The design development phase of the project lays out mechanical, electrical, plumbing, structural and architectural details relating to the audiovisual systems. The technical AV system design drawings are also created at this time. The phase relies on the deliverables from the schematic design phase (the AV program report and opinion of probable cost) as the basis of subsequent design. This is why the schematic design phase, and more specifically the AV program report, are so important: Working off of a structured, thorough and approved program report/OPC is key for the design development phase deliverables and can really reduce the number of revisions made in the process.
Taking a bit of a step back, I will say that sometimes the schematic design phase may include some of the deliverables I'll describe as being part of the design development phase. The architect may put together a preliminary floor plan and wall elevation drawings as part of the schematic design phase, and may ask the AV designer to include AV equipment on those schematic drawings. Generally speaking, I prefer to lump all of the AV design drawings into the design development phase, but stay flexible on a project-by-project basis.
The design development phase mainly consists of meetings with the design team, resulting in the creation of the audiovisual system design CAD drawings. These drawings can be separated into two categories: drawings that are required for AV infrastructure design, and drawings that are needed for the technical AV system design. Drawings showing AV infrastructure requirements may include floor plans, reflected ceiling plans, wall elevations, sections, mounting/installation details, lighting zone plans, schedules and risers. Drawings needed for the AV system design may include single line flow diagrams for audio, video, control and data signals, as well as drawings showing viewing angles, speaker coverage and control system user interface layouts. Sound like a daunting number of drawings? Luckily not all of these drawings are needed for every project.
AV Infrastructure Drawings
The drawings for AV infrastructure design typically show electrical, structural, mechanical and architectural requirements. These include power outlets, network data/phone/cable TV jacks, floor/ceiling/wall/table box locations, junction boxes, HVAC requirements, AV equipment locations and AV equipment installation/mounting details. When creating AV infrastructure drawings, I typically prepare a "50 percent" drawing set (meaning, the basis of the design, open to changes) that acts as a first draft for review with the client/design team, a "90 percent" drawing set that shows all changes, then a "100 percent" drawing set with any final changes reflected. Any drawing revisions after the 100 percent set will be in the form of an addendum or change order. Larger projects that require more coordination may have 30 percent, 50 percent, 90 percent and 100 percent drawing sets issued.
The AV infrastructure drawings are a key tool for the architect and engineers, who incorporate all of that info into the project's main drawing package. This is the set of stamped drawings that the architect will use in the general/electrical contractor bid package. It's important to note that the AV infrastructure drawings contain electrical and structural information that can potentially be dangerous or deadly if not specified properly. It's very important that the project architect and/or engineers approve all of these AV infrastructure specifications. I clearly mark my drawings as "for reference only" and make a point to say that they're not for construction, and are not stamped drawings.
At a minimum, the necessary AV infrastructure drawings are typically: floor plans, reflected ceiling plans, wall elevations, equipment details, schedules and risers. Put in the time to get these drawings correct and complete at this stage of the project, and you'll save yourself many headaches when the contractors are on site. Skimp on these drawings now, and you won't have electrical outlets and conduit where you need them to be. Then you're looking at costly and time-consuming change orders late in the project timeline. You really want to rely on an experienced AV designer/consultant to assemble this CAD drawing package.
The floor plan and reflected ceiling plan drawings should show locations of power outlets, data/phone/cable TV jacks, junction boxes and AV equipment locations. The wall elevation drawings should show all of those same items from a different perspective. The equipment detail drawings should show installation and structural mounting details for all of the AV-related equipment that the general contractor, electrical contractor or other trades will be installing. The included schedules should summarize all the required junction boxes, ceiling/wall/floor boxes and cables. Your riser diagrams will show the path and details of required conduit.
Technical AV System Drawings
The drawings for the technical design of the AV systems typically show signal flow, viewing angles, speaker coverage and control system user interfaces. When creating AV system design drawings, I typically prepare a 90 percent drawing set that allows for last minute changes from the client, then a 100 percent drawing set with any final changes reflected. Any drawing revisions after the 100 percent set will be in the form of an addendum or change order. These technical AV system drawings are often over the head of the client and the rest of the design team, so usually there are not as many revisions compared to the infrastructure drawings.
These AV system drawings will be used when issuing the AV contractor (integrator) bid package. Accurate AV system drawings, along with specifications/scope of work (to be discussed in a future article), will result in accurate and comparable bid responses from multiple AV contractors. Leaving loopholes and vagueness in this design drawing package may result in the AV system design not reflecting the original design intent, as it gets interpreted by the AV contractor's design and engineering staff. Many think of single line flow diagrams as basic drawings just showing the overall intent of the system, but I like to get very detailed on these drawings. Detailed AV system drawings at this point in the project will speed up the shop drawing submittal process (to be discussed in a future article) and will prevent your system from being redesigned by the AV contractor.
