Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

RE: engineers and single family houses

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Unfortunatly, you tell the sad truth. Personaly, I carry the 
crusade farther since the majority of homes that I design are 
for low and moderate income families. The majority of my annual 
fee, however, comes from the few custom homes that I design. But 
it is my opinion that the state of our science must change with 
the times to include more than provisions for the safety of the 
public. We must begin to design for damage mitigation in 
addiiton to protecting the public safety. I feel that this has 
been proven from disasters such as Andrew, or Northridge, or 
Loma Prieta. The sad fact is that the majority of families in 
the low to mid income range invested a life's savings into their 
first home (or second home as they trade up) - just barely 
making ends meet to pay the mortgage and taxes. The extent of 
damage from these diseasters was so sever that these families 
have learned to live with thier damage or went further into debt 
to pay their share of the repair or simply walked away from 
their investment.
I know that the insurance industry walked out of Florida as they 
did in California, but they still set up lobby efforts to 
improve construction standards as well as stiffen up building 
code enforcement. It was through this type of damage that we as 
professionals started to question the validity of conventional 
framing standards.  The changes to the 1994 and  1997 codes 
(such as shearwall aspect ratio's, deflection criteria and 
requirements for load transfers) are far stricter than those 
stated in the conventional framing section (UBC 2326) of each 
year. This implys that there are two ways to go. The first is to 
support the insurance and engineering organizations that strive 
for stiffer lateral systems at a small increase in design and 
construction cost. OR those supported by the developer / builder 
that allow for construction at larger profit margins created by 
minimal compliance that are not necessarily the choice that 
would be held by those buying the homes. I believe that the 
problem starts with the code. Lay persons will not understand 
stricter design standards because the majority of contractor / 
developers that speak their language have convinced them that 
engineers are unscrupules marketeers that would rather bury you 
money in their profession than allow you that nice tile counter 
top or tile roof you want.
The truth is that the developer / contractor is generally the 
bottom feeder looking to maximize his profit at the expense of 
the public. He does this by using a loop-hole provided by the 
International Conference of Building Officials called 
conventional framing. As long as this section of code exists, 
developers / contractors will be able to force local city 
councils to accept appeals that allow for the use of 
conventional framing based upon political blackmail. This has 
happened more times than not in my community as pressure was 
placed upon the "descretion of the building official" to 
collapse under the pressure of loosing 250 homes.  The 
professional community as a whole believes that conventional 
standards may not endanger lives, but will place an unnecessary 
burden on the home owner when his property is severly damaged in 
the next diseaster.
A case in point recognizes that the code requires a shearwall 
ratio of 3.5:1 yet the conventional framing section of the code 
reduces the wall width to 2'-8" x 10' -0" tall (ratio equal 
exceeding 3.5 to 1). Check to see what the story drift is on 
such a panel when the center to center spacing on the holddown 
is one foot less or 1'-8". Unless the shear is very low, you 
 will not be able to work the numbers. (2326.11.4 Alternative 
Braced Wall Panel)
Let's move to Hurricane country. The conventional framing 
section of the code allows for the use of manufactured plated 
roof trusses under conventional framing. However, there is no 
provision in the prescriptive code that explains how to make the 
shear transfer from the roof to the lateral restraint system. 
The use of plated roof trusses is covered under section 2326.1 
as an approved repetitive wood member.
Non-conventional materials can be mixed with conventional 
materials so long as the non-conventional material is designed 
in accordance with section 1603.3 of the UBC.

Now Lew, answer me this question. If this section of the code is 
a prescriptive measure and non-professionals are not required to 
understand or read this section of the code, then how are they 
able to ascertain the need to have engineering involvement when 
their otherwise conventional product contains some 
un-conventional systems? More importantly, section 2326.1 
references to load tables and states that if the gravity loads 
exceed the table values then the gravity load system must be 
designed by a professional. The real question is, how will the 
building official or builder know when a gravity load member 
exceeds the table values without knowing how to run the numbers? 
How often do you see long span 2x8 rafters at 24" on center 
carrying mission tile. It doesn't compute, but no one has 
identified the problem until the owner is force to face the 
problem when damage does begin to show.

I'm really sorry to be so verbose, but I am pasionate on this 
issue because I feel for those building owners that are forced 
into poverty from home damage that may have been prevented by 
our professional community simply by not allowing the publishing 
of the conventional framing section of the code.

Finally, we may be legally bound to protect life safety, but I 
believe we are ethically bound to mitigating damage and 
protecting the nest egg of the public.

My very best regards,