Common Plumbing Design Mistakes 1-10
Click on an item below to view additional information and suggestions on how to avoid the mistake.

1. Insufficient wall/chase spaces preventing installation of piping and/or supports.
   a) Refer to fixture manufacturers installation data and pipe dimension handbooks to verify space requirements.
   b) Coordinate with architect to provide required spaces during development of floor plans .
   c) Increase your knowledge by visiting job sites during construction to observe actual installations of various
        fixtures and piping.
   d) Review the following related information... RepWars-Fixture Chase Spaces.
2. Structural interferences preventing installation of piping and/or supports.
   a) Overlay structural drawings & floor plans to view possible conflicts.
   b) Remember to add fireproofing thickness to structural member dimensions.
   c) Coordinate with architect & structural engineer to resolve conflicts during development of floor plans .
   d) Review the following related information... RepWars-Fixture Locations.
3. Lack of information on drawings required by plan review authority.
   a) Contact local code authority and verify information required on drawings.
   b) Many require; Riser diagrams, Piping material schedule, Roof drainage calcs, Grease interceptor calcs,
        Water heater detail, Gas piping schematic, BFP detail, etc...
4. Improper separation between roof vents and air intakes.
   a) Verify applicable code requirements.
   b) Separation minimums range from 10 to 25 feet.
   c) Coordinate with mechanical engineer and kitchen consultant to locate all roof penetrations.
   d) Develop roof plan to graphically identify and locate all vents, exhausts and air intakes.
5. Failure to provide or properly size combustion air louvers.
   a) Verify applicable code requirements.
   b) Coordinate with mechanical engineer to verify gas fired equipment proposed.
   c) Review related information at...RepWars-Intelligence Reports.
   d) Download this louver sizing calculation form to maintain a record in your project file.
6. Omission of floor drain trap primers.
   a) Provide trap primers for all floor drains not receiving discharge from water supplied fixtures or equipment.
   
7. Specifying plastic pipe within return air plenums.
   a) Coordinate with mechanical engineer and verify locations of all spaces used for return air plenums.
   b) Insure drawings and specifications call for materials located within plenum areas to have a minimum
        25/50 fire/smoke rating.
8. Not specifying an expansion tank for a hot water heater.
   a) Provide a properly sized expansion tank for all water heaters having a check valve or BFP in supply line.
   b) Review related information at...RepWars-Intelligence Reports.
9. Unauthorized or no location of standpipe/sprinkler fire department connection.
   a) Coordinate with local fire marshal and verify requirements.
10. Omitting hose bibbs from exterior walls or mechanical rooms.
    a) Coordinate with owner for desired locations.