How could you risk exposure in what you can't see and didn't witness being built?

I've had to tell my client on occasion that superman couldn't come to take a look.

Depending on the circumstances, the owner or mobile home manufacturer may have some installation instructions available to peruse.  This should be the starting point.  While you cannot testify as to what is below the visible straps unless there are... PICTURES... (I never ask too much do I) you can testify as to what is there and compare it to the HUD requirements.  

If HUD wants numbers that you cannot provide without a limitation of liability (what's that?), then let HUD be the bad guy here.  Never take the responsibility for that which you cannot see.

Mike McCann
MMC Engineering

Do not certify any foundation which you have not inspected during construction.  If you do, and something goes wrong or somebody believes something has gone wrong, you could be facing hundreds of thousands of dollars in liability in years to come.  The risk is too great.  Please, don't do it!  

I only wish I had heeded my own advice fifteen years ago.

BA

Mobile home anchors are "off the shelf" galvanized steel helical anchors that are usually about 4 to 6 feet long, and turned into the ground with a pipe through the "eye" or clevis depending on design.  The helical section is usually 8 to 12 inches in diameter.  Capacity depends completely on soil conditions as the shank has much greater capacity than needed.  Go to a local dealer and look at one.

Lateral force resistance is provided by opposing anchors.

Assuming you have something other than loose sand, 2210# is probably not a big deal.  Load test one of them.

I thought I read somewhere that these helical anchors shall not be permitted to be used as a permanent foundation for a mobile home, regardless of the capacity the anchors may possess.  Does your 1996 HUD document allow them?

K2skis,

In my previous job, I had to do these all the freaking time.

The key word they are looking for is "appears"

Below is the wording of the last one I did.  It didn't pass.  Had it passed, I would have replaced the sentences in parantheses with the sentences in brackets.  Hope it helps.
 
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On April 19, 2006, YOUR NAME HERE of YOUR COMPANY'S NAME HERE visited the above referenced property.  The purpose of this visit was to observe the foundation of the residence and determine if it was in compliance with Permanent Foundations Guide for Manufactured Housing, HUD-007487.  

The curtain wall of the residence is present to keep out vermin, meeting the HUD Publication's standards.  The foundation piers appear to be spaced in accordance with the publication.  The transverse lateral ties appear to be spaced per the publication and placed in concrete.  (However, there were no longitudinal tie downs installed.  In order for this residence to be in compliance with HUD publication, HUD-007487 with 1996 revisions, longitudinal tie downs shall be installed.) [The longitudinal tie downs appeared to be installed per the publication.  The foundation of this residence appears to be in compliance with Permanent Foundations Guide for Manufactured Housing, HUD-007487.]

The scope of this report is limited to matters discussed herein.  No opinion is offered and none should be inferred regarding other aspects of either the structure or the structure taken as a whole.   By accepting this report, you, and any other person, persons, or company to whom it is distributed, agree to a strict limitation of liability for YOUR NAME HERE, YOUR COMPANY'S NAME HERE, and its employees, to an amount not to exceed the fee paid in hand.

Thank you for the opportunity to provide you with this service.  Should you have any questions, or if I can be of further assistance to you, please feel free to contact me.
 

I get phones calls for this on an almost daily basis.  Calls come from homeowners, real estate agents, mortgage companies, etc.

I tell them that your everyday struct eng firm does not have any experience with mobile home tie down systems. But I don't where to direct them. Who should I refer them to?

I was requested to do the FHA certification once.  I don't like telling people to go away, so I looked into it a little bit.  
Apparently most home inspectors will do the certification for a low price, so everybody wins.  The home inspectors don't have to worry as much about getting sued.
The engineer doesn't get the liability and the potential homeowner gets a reasonable cost for filling out government forms.

Thank everyone so much for all of your posts they have been helpfull.  A couple of replies and comments.

The client has to have an engineer due the observations according to the loan officer.

I actually do have pictures and documentations on the 3' deep pier footers.  As for the vertical anchorage I see no reason why we can't remove one see what it is and test it's capacity at another location close to the trailer for further verification.

nutte:  It took quite some digging but I finally found what you may have been refering to Page A-6 Note #4 under C1 foundation type.  This does say screw in anchors are not permitted??????  I don't know really what sense that makes as I thought they were the most prevelant and certainly can provide quite a bit of capacity if you have decent soil.  These certaily provide more capacity than the barbed stakes that I have also seen used.  

I think if I load test the anchorage and have him install the longitudinal and transverse diagonal cable bracing.  I believe I will sleep well at night.

ChipB: Thanks a bunch for the wording to also further help protect my butt.

K2skis, my point was that despite the strength that screw-in anchors have, they are specifically excluded from being used as "permanent foundations."  Yes, they are extremely common, meaning that most mobile homes do not have "permanent foundations" according to this document.

Good point. How would a mobile home have a permanent foundation?  I guess by it's pure definition it can't.

But, we've all seen mobile homes have their wheels/axels taken off and set upon CMU piers and/or a perimeter block wall. At what point does the mobile home become an immobile home?

Here is a link to the document, for those interested.

http://www.huduser.org/publications/destech/permfound.html

http://www.huduser.org/intercept.asp?loc=/Publications/PDF/foundation_guide_complete.pdf

K2skis, you found a reference on page A-6, but there is another one on page 1-2, in the Definitions portion.  To quote the document, "screw-in soil anchors are not considered a permanent anchorage."