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Re: Prescriptive Residential Construction Vs New Design Standards

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Dennis S. Wish PE wrote:

Bob, here are some of the driving concerns.

1. The Insurance Industry reports close to $60 Billion dollars in damage to residential homes from the  Northridge earthquake - Figures are high from Hurricanes such as Andrew. The insurance industry has once again pulled out of California (for earthquake coverage) relying upon a new state plan with an increased deductable from 10% to 15% or more.

RESPONSE:  This is not an engineering issue.  The buildings damaged may or may not have conformed to the code in effect, if any, when they were built.  Changing  code now won't effect any building that already exists, only buildings built after the new code is effect.  Again, not a dime of this money went for life loss or injury.  I would note, however, that the insurance industry is rating building departments and those that permit "unengineered" construction in high wind and earthquake areas will get lower ratings and that will increase premiums in those areas.

2. I believe there is a growing concern that the code must provide for more than life safety - to help reduce the historic level of costly damage resulting from a combination of design inadequacies, and construction quality failures. I believe that other organizations believe this to be true - National Association of Home Builders Research Center seems very concerned with this issue - and I applaud them for finding the financial bodies.

RESPONSE:  This is a political issue.  If the people want quality construction or consumer protection from government (ie the code) they will have to legislate it and be willing to pay for it

3. I have been pretty clear about my concerns with the marketing of a residential homes. It should be easy for you to prove that the majority of homebuyers believe that all homes are protected by code and are designed by the same methodology. You and I know that is not the case - and so does the developer. Mind you, devlopers of large tracts like Kauffman and Broad can't get away with this - but the small developer of five to ten homes a year can and does. He is smart enough to know exactly where his money is spent in the construction of a residential home and knows full well that he is protected from liablity as long as he complies with conventions framing provisions.

RESPONSE:  Homeowners haven't got a clue what they are buying.  They are far more interested in what the monthly payment is going to be.  Given a choice between better seismic performance and free landscping in the front yard, I think we both know what they will pick.

I believe it is unethical to sell two products and depict them to be of the same quality when the fact is that one will not come up to the numeric standards of the other (and thus will not perform the same). In this case, I believe the public needs protection by disclosure.  they should be aware of the homes expected performance standard so as to make an intellegent choice based upon disclosure of the facts.

RESPONSE:  I don't believe any such "deception" is going on.  See also last answer above.

4. There are quite a few ommissions in the prescriptive method that can lead to problems in the field. 

Tell me where, in this section of the code, it lead the non-professional to a prescriptive beam or header design? It does mention that headers need to be designed but does not stipulate how or by whom. Therefore, the building official historically accepts the contractor or builders plans which arbitrarily pick header and beam sizes. 

RESPONSE:  When was the last time a header or beamed failed injuring or killing some one?  Contractor's in my experience generally oversize these members.  I have investigated far more "failures" of engineered beams.

What happens when a prescriptive set of plans is submitted for permit issuance and the building department technician is neither an engineer of architect? As long as his interpretation matchs the contractors (who must have historically been doing it right to get so many permits in our town) who finds the mistakes?

RESPONSE:  If you don't need to be licensed to design it why would you need a license to check it?  It is much more of a concern that many "engineered" plans are still checked by unlicensed persons even though BORPELS says plan checking is engineering.

You suggest that "The California Contractor's State License Board is also in the process of developing a "merit badge" system. " I would applaud this but when will it cover these issues. When will the CCSLB require a framer to be required to have an understanding of this section of the code. Today, anyone who can lift a hammer can call themselves a "Framer" - very few whom I've met have ever looked at the UBC.

RESPONSE: Your going to have to take this one up with the CSLB.  But why isn't SEAOC providing training for framers?

Where in the discussion of interior braced walls does it explain that the top of the interior resisting wall must be connected to the roof diaphragm? I don't see a reference to top of wall connection in 2320.11.3 or 2320.11.4 of the '97 code (or anywere else in section 2320.11) and don't remember seeing it in either the '91 or '94 UBC. 

RESPONSE:  This is an area that needs to be addressed.  The code change was submitted and then ICBO suspended code modifications in favor of the IBC.  There is still time for you to submit a challenge to the equivilant section of the IBC if you wish.

Is the framer or designer expected to sign the plans to verify that he or she has designed in compliance with conventional framing and understands both the rhetoric and intention of this code section? Or, is compliance to conventional framing standards the responsiblity of the building official to detect?

RESPONSE: Signing requirements vary by jurisdiction.  See UBC 106.3.2.  Compliance with the code is always the responsibility of the person requesting the permit.

My last comment is to your statement "Remember, we can always add to the code to make construction more expensive but only at significant social costs.". 

I agree with you here and this is why I have such a problem with Conventional framing provisions. Unless you write a code that can be followed without the need of "designed" elements, you invite misinterpretation and errors in construction. The code is written for professionals, not laypersons. The extent of damage from Northridge Earthtquake created stricter codes (which conventional framing remains exempt). Therefore, the code is used to maken construction more costly and the expense of a discontinuity within the building industry.

RESPONSE:  Eliminating "designed elements" would require a change in law not code.  I doubt this could happen.  Prior to the current law, residence were exempt from engineering period, regardless of how unsusual their size or shape was.

DENNIS:  My point is that we have to careful what we ask for.  By and large, conventional construction has performed well.  I believe we have to find out why and then make code modifications that encourage its best features and eliminate those that have not worked.  The idea of requiring all buildings to be engineered or "making conventional contruction calc" are not reasonable attainable goals if the protection of life safety is the purpose of the code.  The engineering community (SEAOC) could help greatlly in this area if we started a dialogue with the our elected representatives and the construcxtion industry on this issue.  Our involvment in the training of those who build our homes would go far further than any code change would.