Manufactured Home Foundation Question

[inspectorwill]

I came across a manufactured home yesterday with a foundation system I am not familiar with. I have inspected many manufactured homes and they all have the same type of foundation but this one is different. The steel I-beams are set directly on poured concrete foundation walls and piers. I cannot see any means of fastening between the I-beam and the concrete walls. I am curious if there is a typical fastening method that would not be visible from the crawlspace. At the concrete piers, I can see a 360 degree view and do not see any fasteners. Additionally, the walls on the exterior are not square relative to the foundation. Unknown if this was poor original construction or indicative of movement. There are no cracks at the exterior walls. I will ultimately refer this out based on the observations but would like to know for future reference as to the methods typically used to fasten steel beams to concrete foundation walls. Thanks. Couple pics of the exterior walls and foundation attached.

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[Jerry Lozier]

I've never seen that either .... is that a holddown bolt/nut in 3rd picture or leftover axle removal nut?

I see no tiedowns and sitting on blocks in older pre1980 MH all the time,(usually in MH parks) but with our current siesmic structural engineers want tiedowns every 10-14'.... whats the age???

aren't you sitting on San Andreas Fault????

Jerry (I was born and raised in Paso Robles)

[inspectorwill]

The bolt in the picture fastens the two sections of the home together (marriage bolt). The home is a 1973 and it is located in Southern California which is riddled with faults. The San Andreas is not nearby but I'm sure there are plenty more faults that could be equally destructive.

[patt]

Just a note on terminology unless you know for sure that it is a "foundation system" you should just call it the "system support". A 1973 home, at the time of installation, would not have required any attachment to its support system.

In CA you install the home to manufacturers' installation, plus since 1994 there has been a requirement for a "tie-down system". Tie-down systems are to prevent over turning and lateral movement caused by wind loads. The tie-down system used can be the typical auger and straps, the instructions for which are included with the manufacturers instructions for the set up of the home, or an engineered pier system which is what is most commonly seen.

Additionally in CA you also have "Foundation systems" and "Earthquake Resistant Bracing Systems (ERBS)". Foundation systems are really just a combination of the manufacturers basic support requirements, and tie-down and seismic requirements. Foundation systems may consist of just an additional pier system or may utilize a perimeter concrete or cmu stem wall. If the home is placed on private land, not rented land, and a "foundation system" is used then the home can be considered as an "a fixture or improvement to the real property" in effect converting it from personal property to real property and qualifying for better financing.

Attached is a drawing of one manufacturer's home attachment to a stem wall foundation, from either outside or underneath you would not be able to see the connection.

Download Attachment: Stem wall.pdf

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