structural reviews

huangyhg

structural reviews
please read this quote...
"peoria now, for example, is requiring a structural analysis by an engineer on all homes that put solar on. that's a deal killer. if you find an engineer who is cheap, you may get by with $600, more likely $1,000, for every system. in a sense, peoria is saying they don't want solar on their homes," neary said. "it's generally a deal-breaker."
i provide the structural engineering for many of these.  when this quote came out in a local publication the cities reversed their positions.  the issue i have with this is there are many valid reasons to provide engineering for these.   why is it, that money for a structural review is governing the safety of human life?  as i recall, that's why we're all doing what we do.  
i'm currently putting together a powerpoint presentation to my local mag committee.  if anybody has any opinions, ideas, feedback whatever - i welcome it.  
if you would like to see the rest of this article:
when you are talking trusses, i do not see how this will be an extra $600.00 when the trusses have to be designed aqnd stamped by a structural engineer anyway...
are these new or existng trusses, or, new or existing stick framing, that the article was referring to?
mike mccann
mmc engineering
this is a retro fit application.  the truss, joist, rafter, beams etc. have to be reverse engineered.  we do stamp the engineering & cover letter, same as a tenant improvement.  
regards,
ray
got it...
mike mccann
mmc engineering
it does sound like overkill to me to require engineering evaluation of houses for installation of solar panels.  they don't weigh much, unless you are putting storage tanks on the roof.
our populist government in australia is giving $8000 rebates for installation of solar panels.  as far as i know, no individual structural assessment of the roof is required.
that's true they don't weight much psf.  the problem is that the installers are having to be more and more competitive and pushing the capacity of the railing system w/ as few roof penetrations as possible.  in some cases the clearspan is 6' wide and 5' deep with connections (depending on the installers application) having a single leg supporting 2 arrays (doubling my trib area).  
it's not just gravity that causes issues, its wind.  the added dead + wind tend to fail in combined stress on the top or bottom chords (tension / compression + bending).  the other wind issues are where these systems are on a flat roof and on a tilted mounting system sloping +/-30 degrees.  i've now got a sail to worry about with positive and negative pressure (rotation) on the same   
for existing conditions just have them remove 4 of the 5 layers of old roofing material to reduce the weight so you can claim you've improved the structures performance.
that's assuming asphalt shingles exist & multiple layers have been applied.  i have seen some remove the tile and lay shingles for those locations where the solar is being located.  this proves to be a much better application however, the questions remains.  who is responsible?  
if framing were done the same perhaps i could take comfort in that a case study could be made.  every home is usually framed by a different contractor with many crews who purchased lumber & trusses from one of many suppliers.

here's a thought- nobody is going to be walking on top of these things. do they weigh more than 12 psf? if not, they essentially would replace the roof live load, wouldn't they?
of course, your load duration factor is more severe for dead than roof live, but at least that's a reasonable way of looking at it, in my opinion.
btw- i'm not familiar with the irc. are the roof live load requirements the same as in the ibc? (that's where i got the 12 psf- this is "worst case" in the sense that i'm assuming the   
this is the strongest argument that has been brought up and could be valid as long as it's construction live load.  it still doesn't mean that the members below would perform successfully.  once you move into elevations where snow is figured, the snow live load couldn't be substituted for dead load.
once these structures are modified, do they get brought up to existing building codes (the modified supporting members)?  ubc vs 2006 irc / ibc poses new wind issues that can cause components to fail by that change alone.   how would one go about checking an existing   
i saw a news report yesterday where a family was being charged $100,000 (i think) to convert their house to alternative energy (solar and geothermal).  after government rebates (state and federal) they were paying $53,000.  i can't believe $1000 would be a deal breaker.