"Required" Calculations

[PMR06]

Many forums have come up lately regarding "requiring" calculations, that I have some related general questions to pose:

Who pays for the preparation of calculations? Who pays for the time it takes to review & respond to review comments of those calculations?

Does the reviewer of submitted calculations take on some liability?

Why do ASCE 7 and model building codes not clearly define the extent of calculations?

When did having a PE license lose it's credibility to back up a design that now calculations are "required"?

 

[graybeach]

From the owners side, I often find it beneficial to review calculations. For example, if a consultant comes up with a recommendation that lowers the load rating for a particular element, I want to make sure it is really necessary. Usually I just spot check the critical numbers and try not to second quess too much. There have been times that I found mistakes in sealed calculations that might have been very costly to us.

If an owner does not have knowlegible engineers on staff, they can hire an independent engineer to review calculations for critical items.

Or, if no one reviews - just seeing that calculations have been done and checked is good due diligence.

 

[whyun]

Calculations demonstrate the thought process of the engineer who designed the end product. If it is sloppy, you can form opinions about the engineer's competency.

Building officials should review calculations AND drawings for code compliance PLUS any life/safety issues not addressed in the code. Requiring calcs for details shown on the drawings without calculations is perfectly justified, in my opinion. But asking for detailed calculations that take a lot of time/money, which in the end do not change the design shown the first time, is a bit out of line.

 

[DonPhillips]

Whyun,

I disagree the building official (BO) should review calculations if designed by a registered design professional, the drawings are sealed and contain all the information required by the code. Otherwise this would be akin to a design professional getting involved in means and methods of a contractor. The design professional has to take responsibility for the design and if the BO misses something in the calculations, may take on some of that responsibility.

Now for 1- and 2-family residential where most jurisdictions except these from seal requirements, I would typically want the calculations to review. But we are typically talking about joist, rafter, and beam spans, that are relatively straight forward.


Don Phillips

http://worthingtonengineering.com

 

[DonPhillips]

Whyun,

Forgot another thing. Building Officials do not have the authority to enforce life/safety issues not addressed in the code. If it is not regulated, they cannot enforce it. Similarly, they cannot grant variences either.


Don Phillips

http://worthingtonengineering.com

 

[BRGENG]

The first step my company takes for every project is to contact the Local Building Code Authority and verify the Local Building Code, Snow Load, Wind Load, Seismic Info, etc, and are Structural Calculations required. This five minute phone call can save you hours later. Also be sure to check and verify how many sets of drawings and if they all need to be wet signed and sealed.

If you know Calculations are going to be required it is simple to keep a project folder during design and add the calc’s as you go. This should be done with every project regardless if the code official wants a copy.

In office, we have every single project reviewed (including calculations) before the plans are sealed and leave the building. Since we use many in-house spreadsheets for our calculations we also include a word document that explain how the program works and shows the hidden calc’s not shown on the output sheet. This also allows you to update the program when the Code changes every three years.

As a reviewer for several different Cities we require calculations to be submitted with the drawings. It is amazing how many mistakes I see, especially in Wind and Seismic Calculations. I seriously think that many engineers have not realized that the ASCE 7 is updated every 3 years. We require IBC 2006 in our area, last week I had a design come through based on the 1996 BOCA code. Yet they used an older version of Enercalc that is based on the 1997 UBC code. I would estimate that a quarter of the buildings we review have no lateral design calculations. Some Engineers have called our office and asked what we mean by lateral calculations, do people really not know? Just because an engineer has signed and sealed the plans doesn’t mean that errors don’t slip through.

I photo copy mistakes we see and put them in a book, one to teach our new engineers what not to do. Maybe one day I will travel the circuit of overpriced Professional conventions and speak about them. At least it will keep you awake.

 

[Lion06]

I think a building inspector (or someone from his office) reviewing calcs for the entire project may be overdoing it a bit. Additionally, while I feel there may be some benefit to it, it seems like the cost (time) far outweighs the benefit. I am not saying a lost life isn't worth the time, I am saying that most companies have in house review processes and it is ultimately their professional liability on the line and, as a result, they have the greatest incentive to make sure the design is up to snuff (They being the EOR).
That being said, a prudent EOR should be reviewing calcs for anything that is within the scope of his work that was farmed out as "performance spec" (e.g. metal studs, stairs, etc..). Again, the liability ultimately rests with the EOR and the defense of, "well a different PE designed it, I only approved it" isn't going to cut it.
The building inspector's office isn't taking on any liability by reviewing calcs.
I guess if the calcs were reviewed in a fashion so as to make sure no grossly large errors were made would be more appropriate than nit-picking that the CMU back-up should be 90plf not the 88plf that the EOR state because he rounded a little in an earlier step. That just seems a bit much to me.
If there is no lateral system as mentioned above, that is certainly cause for concern. If you disagree with a load by 2%, let's not forget the factors of safety inherently involved in any structural design calculation (some of which are meant to directly account for things like that).

 

[whyun]

Don Phillips,

I agree that IF "designed by a registered design professional, the drawings are sealed and contain all the information required by the code", there is absolutely no need for a Building Official. However, someone has verify that the drawings indeed "contain all the information required by the code". Should every project be peer-reviewed?

Let's presume that the drawings are 100% code compliant and it is in the hands of a contractor. Does the EOR perform site visits at critical phases of the project to ensure that contractor is doing the right thing?

In this profession, we need proper amounts of checks and balances by all parties involved.

Typically building inspectors are not licensed engineers. If they do not possess a PE license, they are not qualified to review calculations by EOR.

 

[PEinc]

I think that some reviewers want the calcs for their continuing (or initial) education, especially if the design is something they are not very familiar with.