structural certification for manufactured home

huangyhg

structural certification for manufactured home
hi - i have a question about an engineering certification for a manufactured home.  this particular home was installed in the early 90's - it has had a side porch and a front porch added to it.  specifically, i have to provide an "engineer's certification report" that indicates that the structural additions and modifications were made in accordance with the hud manufactured home construction and safety standards (hud document 3280 - manufactured home construction and safety standards).
i've looked over this standard, and it looks like section 3280.305 of this document ("structural design requirements") is what applies...?  has anyone done one of these certifications?  any advice would be appreciated.
thanks!
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what the local jurisdiction, financial or insurance company is looking for is a statement that the additional porch, deck or roof is not impinging on the structure of the manufactured home that, in all likelihood, was not designed to accept these additions.  without this statement, the original warranty for the structure could be voided.  not an acceptable condition for a purchase or refi...
i would wonder if these additions were permitted too...
  
mike mccann
mmc engineering
hi mike,
thanks for your response.
i don't have all of the info on this job yet... what i do know is that the present owner paid cash for the home and may not have a lot of documentation on the home or any of the work that was done on it.
for this job i have to do a couple of things:
1) certify that the manufactured home's foundation meets the guidelines specified in the hud permanent foundations guide for manufactured housing (1996)
2) certify that the structural additions and modifications were made in accordance with the hud manufactured home construction and safety standards (hud document 3280 - manufactured home construction and safety standards).
for item #1, basically i'd be inspecting the foundation to make sure it meets the 1996 guidelines (i've done a few of these... usually the one element that they're lacking is the required lateral bracing).
item #2 is a certification that i have not done before. i'm assuming that i would need to analyze the manufactured home structure itself (and the additions) to make sure that they are good for the loads in hud document 3280.  but since i probably will not have any of the plans for the home or the additions, i'm not really sure how to go about this.  it sounds like it might be a lot of estimating and guesswork...
do you have any advice you could give me on this?
thanks!

i've looked at a few of these also and i'm surprised that the only thing you mention as "usually" lacking is the one item. i have found that more often than not, there are several things that are not in compliance with the hud guidelines.
my biggest questions are:
what do you do about the non-compliance?
how do you get paid when you tell them something that they don't want to hear? (usually the inspection is required for a loan approval. when you say no good, the loan can't happen.
do you have to design installation of the "missing" components?
do you re-inspect?
usually the components are missing for a reason (like it's a pain to install for whatever reason). are you involved in the resolution?
my experience is that these things are difficult to do well and without an inordinate amount of wasted time. do you find otherwise?

the question you need to answer for certification is "do the additions impart additional load to the manufactured home, or do they stand alone structurally?"
if they stand alone, if becomes a non-issue and can be handled with a single statement in your certification report.  
if they do not stande alone, then you will either have to analyze the mobile home for the additional loads, probably with insufficxient information without some local disassembly of the home, or recommend that the additions be modified so that they are not supported by the mobile home in any way.
mike mccann
mmc engineering
mike - thanks for your advice.  you summarized the situation well - it's really clear to me what i'll need to do for this job.  you've been very helpful!
houseguy...  the homes i've inspected have been ok as far as vertical stability goes (adequate anchorage to prevent uplifting and overturning due to wind or seismic loads; footing sizes good for soil-bearing capacity, etc., etc.).  lack of lateral stability is the main problem i've encountered (i.e. the homes have no anchorage or bracing to prevent sliding due to wind or seismic loads in the transverse and longitudinal directions).
after the initial inspection i sit down with the homeowner and explain what needs to be done in order to bring it into compliance with the 1996 hud guidelines.  the homeowners that i've dealt with have been willing to do whatever is required - they need to if they want to get their loan approved.
i don't design the lateral bracing - there are a number of proprietary products available that can be used for retrofits.  my thought is that it makes more sense to use something that has already been designed for that specific purpose, rather than redesigning the wheel.  e.g. in the past i've recommended the use of tie down engineering's xi2 foundation system.  the systems are fairly easy (and fast) for a contractor to install.  after the installation i do one more inspection to verify that the bracing systems have been installed correctly (placed in the locations i have specified and installed per the manufacturer's instructions).

i do not know much about manufactured homes, but i seem to recall the unit should have a placard on it with a serial number and the manufacturer.  if found, and the manufacturer is still in business, may be a source of information.
  
don phillips
been there and was not impressed unless a lot of documentation is available.
why put your license and reputation on the line.  drop it.
if something goes wrong - whoever wants the report will be on you like stink on .........
thanks for your input everyone.
miketheengineer - i think you've summed up the way i'm starting to feel about this job... if there isn't anything documenting the existing home or its additions, i'll pass.