146 Chapter 6
- Heat-loss and heat-gain calculations per area
- Round-duct, turning-vane, and lay-in-diffuser details
- Special conditions, such as seismic restraint codes
Engineer’s drawings are required for all commercial projects involving HVAC work, including addi-
tions, renovations, or new construction. A permit is required prior to commencing any on-site work.
Drawings and permits are also needed for residential projects when any substantial work related to
HVAC is to take place. For small projects, a licensed mechanical contractor can provide the information
required to obtain a permit.
Concept and designs are the first stage of any project. When established, the next stage is con-
struction drawings. Once the floor and reflected-ceiling plans are complete, they are passed to the en-
gineer to produce the mechanical drawings. The engineer’s drawings become part of the construction
drawing set.
Figure 6.17B Diagram showing HVAC ducting sizes, connections, and layout.