What governs - engineered design, or common sense?

[Darren Emery]

I'd like to discuss a purely hypothetical situation. Nothing like this would ever happen. Right?

Type 1 kitchen hood is designed by PE, everything on paper looks great. Resturant owner buys different equipment, and work in the field stops when inspector realizes nothing matches plans.

Signficant change to make up air location and duct work. Original back shelf plenum (6" x 72") gets redesigned and choked downt to 6" x 12". PE puts a note on the plans to increase the speed on the MAU fan to compensate for the restriction.

Mechanical contractor responsible for the install balks - he knows this thing won't supply correct cfm due to the choke point, and very likely will not pass balance test or perform well.

As an inspector, what do you do? Approve because it's as designed on plans...or tell them all to go back to the drawing board and come up with a better solution. Or something in between?

 

[cda]

If the engineer has put his name on it and you are at the point to do the air balance

Require the test

If it passes so be it

If it fails redesign resubmit

Or require third party eval

 

[Sifu]

It makes me a little sick to even say this but sometimes it comes down to it; What would the judge or jury say? Would they say that a reasonable inspector should have known the system wouldn't work even if the PE says it would? If so would they say you share some liability? Would they ask if you were suspicious, and the contractor refused to install because he was suspicious why were those suspicions ignored? Or, on the other hand, would they ask who you think you are to question the professional standards of a PE? These are not rhetorical questions, rather they are questions I truly wonder about. I see PE designs and letters I believe are questionable sometimes and I am left with those questions. Some may say you have an obligation to question and others may say brush it off, its now the PE's problem. I have called a PE or 2 and voiced my concerns and it usually works out, usually him explaining to me in a satisfactory way why his design will work.

 

[mtlogcabin]

Ask the PE to provide the calculations showing it will work. I bet you will get something different after that. If not file the calcs with the permit and move on. When it it hits the fan because it is noisy or does not work you can point to a designed system. Some times when a PE has to acutually spend time on reviewin a change they will change their design/comment

 

[globe trekker]

Darren

IMO, Legally, "What governs" is the design! There should be some discussion

by the interested parties, as to the actual functionality of the submitted

design. The inspector should inspect to the code and to see if the

designed system meets that code. If it does, the inspector (the AHJ) is

finished. If the designed system meets code, but does not actually

perform at an optimal setting, that would be between the PE, ..the

mech. contractor & the owner.

While the inspector may have some valuable common sense & working

experience / knowledge of the system in question, it is not your (the AHJ)

position to require that optimal setting. You would be, IMO, be assisting

in the installation / design of the system. The PE, mech. contractor or

owner could start pointing fingers.

.

 

[Mark K]

Does the engineered design comply with the criteria in the code? You have the right to ask for calculations. If so let the project proceed as long as the work complies with the code compliant design.

If your department does not have the capability to evaluate the designs and are not willing to retain a consultant to perform the review you probably will have difficulty in rejecting the design.

If the completed system does not pass any required tests the AHJ has the authority to reject the work as non-compliant.

The mechanical contractor’s reluctance is an issue to be resolved by the owner, general contractor, and the mechanical contractor not the AHJ.

If the building department has followed the proper process there should be no liability for the department or the inspector.

If the building official believes that the design does not comply with the code, based on fact not suspicion, the building official should reject the design even if the design was signed by a PE. A PE’s seal and signature does not relieve the building official of his obligation to enforce the adopted code. If the question of code compliance hangs on the validity of calculations or specialized technical knowledge the AHJ should have the engineers justification reviewed by somebody qualified, typically a PE, to perform such calculations. Everything needs to be tied back to the letter of the formally adopted code, not what some individual believes the code says.