Manufactured home foundation question

Ed DeRousse · 12-19-2010, 03:33 PM

I looked at a modular home yesterday, that in all honesty, I don't see a lot of. This home was anchored to pier type structures, by use of straps tied to what looked like diagonal metal plates attached to the main beam. Around the perimeter of the home, there was a block wall that to me, really looked like it was playing the part of a skirt. However, there were areas of cracked, jagged cinder block in this wall; there was some loose block, several loose vent covers, and around the top of the wall where the sill plate would normally sit, there was brick. And in one area, the brick was also loose. The understructure of this building was covered with a tarp type cover, so it was not possible to evaluate this part of the structure. I did call this out for further evaluation, because although I do believe that the wall was playing the part of a skirt, I was also thinking that it was possible that these areas of concern could still be being caused by movement of the foundation; and with the tarp type cover, further evaluation by me, was limited. I do have some pictures of my concerns, but I'm not sure how to attach them to this posting. I guess my question is, did I call this right in everyones opinion, and where can I learn more about this subject?

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**Jerry Peck** · 12-19-2010, 04:30 PM

Originally Posted by Ed DeRousse

I looked at a modular home ...

This home was anchored to pier type structures, by use of straps tied to what looked like diagonal metal plates attached to the main beam.

The understructure of this building was covered with a tarp type cover,

Sounds like you are describing a "manufactured home" (old term: 'mobile home') and not a "modular home".

**Hank Spinnler** · 12-19-2010, 05:02 PM

The underside vapor retarder material is referred to as the "belly". The block skirt is just that, a permanent skirt. Often, the belly has been cut. Nachi TV has a video entitled "Understanding Modular Homes" - although it says it covers how both modular and manufactured homes are built.

**Jack Feldmann** · 12-19-2010, 05:02 PM

That be a trailer, Bubba!

**Door Guy** · 12-20-2010, 05:34 AM

Manufactured homes are homes built off site and normally to building code. Moblile homes are built off site but to HUD standards. They have their own roof loads and foundation specs. The piers and strapping your seeing is the foundation and hold down system. The only way to verify the foundation is to have the print from the manufacturer of the structure showing location, depth and size of pier. Most likely the block around the perimeter is nothing more than skirting. The "tarp" is a vapor barrier and actually helps protect during transport.

**Stuart Brooks** · 12-20-2010, 10:29 AM

Originally Posted by Ed DeRousse

I looked at a modular home yesterday, that in all honesty, I don't see a lot of. This home was anchored to pier type structures, by use of straps tied to what looked like diagonal metal plates attached to the main beam. Around the perimeter of the home, there was a block wall that to me, really looked like it was playing the part of a skirt. However, there were areas of cracked, jagged cinder block in this wall; there was some loose block, several loose vent covers, and around the top of the wall where the sill plate would normally sit, there was brick. And in one area, the brick was also loose. The understructure of this building was covered with a tarp type cover, so it was not possible to evaluate this part of the structure. I did call this out for further evaluation, because although I do believe that the wall was playing the part of a skirt, I was also thinking that it was possible that these areas of concern could still be being caused by movement of the foundation; and with the tarp type cover, further evaluation by me, was limited. I do have some pictures of my concerns, but I'm not sure how to attach them to this posting. I guess my question is, did I call this right in everyones opinion, and where can I learn more about this subject?

Ed - Send me a private note with contact info or give me a call. I'll give you a hand.

**Scott Patterson** · 12-20-2010, 12:45 PM

Originally Posted by Door Guy

Manufactured homes are homes built off site and normally to building code. Moblile homes are built off site but to HUD standards. They have their own roof loads and foundation specs. The piers and strapping your seeing is the foundation and hold down system. The only way to verify the foundation is to have the print from the manufacturer of the structure showing location, depth and size of pier. Most likely the block around the perimeter is nothing more than skirting. The "tarp" is a vapor barrier and actually helps protect during transport.

Manufactured and Mobile homes are the same critter. They are actually built to DOT (Department of Transportation) standards which are also modified HUD requirements. They are all brought to the site on their own wheels that are then removed from the undercarriage.

A modular home is a factory built and site assembled product that is usually built to IRC codes. They are brought to the site (usually in 3 sections) on a trailer and placed on the foundation that has been built for them.

Both can meet HUD/FHA requirements.

**Gregory Booth** · 12-20-2010, 02:03 PM

Some accurate information and some inaccurate information here. The term "mobile home" applies to units built before 1976. The watershed year of 1976 was the adoption of HUD code standards which apply to all manufactured homes across the country. These are homes which are permanently affixed to longitudinal steel beams, usually 99 inches o.c., with steel outriggers extending to the side wall. Support is provided with piers arranged along the beams, with the number and spacing always being stipulated by the manufacturer. Sometimes support is provided at the perimeter to increase snow load capacities, but most often the perimeter walls are simply skirt walls. Axles and wheels are affixed to the beams and are usually removed at installation time. There is a belly-board, usually a flexible vinyl, suspended between the beams--this forms a below-floor space that the industry refers to as the " basement". Within this space are the heat runs, water supply lines and the DWV piping. These homes are configured in single, double and triple widths, with the "basic box" being a nominal 12, 14 or 16 foot width--current max. length is a nominal 80'. All plants have compliance inspectors on-site to assure conformance with HUD code. As in all endeavors of man, some factories produce better products than others, but there is basic consistency overall. Modular homes are also factory built, but are built to IRC or individual state building codes. They are delivered on trailers and are craned or rolled on to "traditional' foundations with full perimeter support and center-line lally columns (piers for crawl-space). There is typically no belly wrap and no floor insulation--the main supply plumbing, DWV and heating appliance normally seen in stick built homes is added on-site. A major difference is usually seen in the roof structure, with frame members most closely akin to stick built, although many times there will be hinge systems to allow for greater than 4/12 pitches. Most often mods are seen with two sections but current practices have offerings with multiple sections, second stories, dormers, side "wings" and the like. Finally, just to confuse the issue, some manufacturers are building a HUD code product with a recessed steel frame, which installs like a mod with perimeter and center-line support but with in-floor utilities like a HUD code. They are called "easy set" basement systems-installers call them "hudulars", among other not-so-kind terminology.