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Re: engineers and single family houses

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Stan,
I understand that the state has exempted residential construction from
requiring engineering - and with the use of brick veneer, uplift from wind
would be minimal if any for winds under say 90 mph.
My question was not whether it is allowed or not, but whether it is wise to
exempt a wood framed structure (residential) from proper design against wind
damage. In one of the other posts it was suggested that we do not pay close
enough interest in wind - but rather in seismic since we are in a high
seismic zone. This is not true for residential design.
In my typical design, I compare wind shear to seismic shear in each line of
restraint provided and design the shear elements for the worst of the two.
This is standard practice as far as I can tell (having plan checked many
structures in the area).
In most cases, Wind goverens in lightweight structures with parapets and
gabled roofs with shingle or lightweight tile. The rare times that seismic
governs is when the diaphragm is very deep (increasing the lateral weight)
and very heavy (such as with the use of mission tile or concrete tile).  In
most other cases, wind will tend to govern and the load path is protected
from the roof down in the same fashion had seismic been the governing force.
The real question has to do with the quality of residential construction
based upon a prescriptive methodology. Is the load path maintained from roof
to foundation and do the laterally resisting elements provide enough
strength to resist the diaphram forces. If so, do they prevent the story
drift by code allowable limits (0.005h)?

I think that if you ran the numbers on typical shear panels 4'-0" wide by
8'-0" tall  you will find that in the design of most larger homes the walls
will exceed this deflection limit - if based upon conventional framing
standards in the UBC.

I agree that most homes will not collapse in a high wind (or earthquake) but
the issue has more to do with cost to repair damage.

I think that the focus has changed where residential design is concerned.
The UBC has historically limited their concerns for residential to
multi-family units and opted to let single family dwellings be built without
professional intervention. However, the insurance industry has been the
driving force for reform on this issue based upon the cost to repair a
damaged structure based upon property values on a geographic breakdown. What
I mean is that areas such as California which demands high prices for small
homes has the greatest impact upon insurance claimes than say Springdale
Utah where the cost of home building is still reasonably low.

I'll stop now that I think you understand my concern. I would not be so
concerned if the prescriptive methods were properly engineered for each
condition they are to be applied and that local building inspectors were
properly trained to identify a discontinuity in the load path.

Dennis Wish PE