What to Know About The Inspection of Manufactured Homes

I have written this article to help home inspectors know how to perform a professional Inspection of Manufactured Homes. In this article, I provide HUD codes that are helpful for identifying possible problems; I note this code especially when these are different from the IRC (International Residential Code). For homeowners, I apologize; while there is good information in this article for you, most of this article is very technical and intended for construction and inspection professionals. This particular article is based on training I have received over the years from The ASHI School as well as from HUD code.

Inspection of Manufactured Homes

Advantages of Manufacture Homes Over Site Built Homes

A site built home has the advantage of more design possibilities and flexibility in where to build a home. However, for site built homes, having to build during inclement weather can affect the quality of the build. Compare this with a factory built home. A manufactured home (MHU) is built with an assembly line of people who’ve been trained for certain jobs and the home is being assembled in ideal temperature conditions. Issues with MHUs can be zoning allowing for these manufactured homes. More and more, municipalities do not allow zoning for these homes.

What Is A “Manufactured” Home?

A manufactured home is a term defined by HUD regulations which is part of the federal government. “A factory-built transportable structure assembled on a permanent chassis and designed to be used as a dwelling. More than 8 feet wide and more than forty feet long or more than three hundred twenty square feet.” What’s the difference between a mobile home and manufactured home? These were referred to as a mobile home before June 15th, 1976 when there were no federal HUD codes. Prior to this date there were no standards governing the construction of mobile homes. It is good to confirm a mortgage can be secured for a mobile home built prior to this date. A manufactured home is not required to be on a permanent foundation, however a “modular” home, which is something else entirely, is required to be placed on a permanent foundation. Modular home construction is governed by local city code, not HUD federal regulations. Panel (structural insulated panels) homes and buildings are also factory built and are manufactured per local state or city code. Here are a few historical dates to be aware of:

  • Pre 1054 – Mobile homes were 8 feet wide
  • 1954-59 – Mobile homes were enlarged to 10 feet wide
  • 1959 – Mobiles home were built 12 feet wide
  • 1960 – The first double wide mobile home was constructed
  • 1976 – a federally regulated design of a manufactured home went into affect governed by HUD (also ANSI A-119.1 standard was created to improve the quality of construction)
  • 1980 An “approved products” list of manufactured homes went into affect for each state
  • 1994 – Wind load requirements requiring the use of “tie-downs” went into force
  • 1999/2001 –  Further requirements were added to the installation of manufactured homes
  • 2004 – Licensing become required to install a manufactured home
  • 2009 – HUD expanded to regulate not only the construction, but also the installation of manufactured homes

Important Things For Homeowners To Know

Inspection of Manufactured Homes

Red HUD label or tag

On the tail end of each section of a manufactured home, there should be a red HUD label or tag. The red tag is federal. It is important to report the absence of these tags as this can be a mortgage issue if these tags are missing. There may also be a state tag installed which serve as proof of inspection. These are generally green, cream, or silver. Data plates are another document of important information that can be located in any accessible location. It should be reported if the data plate is missing. If these are missing, the serial number can be used to back-track to find the information on the HUD label and data plate. The HUD label is far more important that the data plate. The serial number can be difficult to find but is located somewhere on each transportable section of the chassis. The chassis is visible in the crawlspace. There is a marriage-wall where sections of the home are connected together at the mating line of the home. These can be identified in the crawlspace and attic in many cases.

Manufactured homes are individually built for installation in specific states. They cannot be installed in a state not listed on the data plate along with the wind load rating of that specific MHU. This data plate can usually be located at the main electrical panel of the trailer, but can be located almost anywhere. Other somewhat common locations are inside kitchen or bathroom cabinets, on a cabinet door, or even on the back of closet doors.

Modular homes Defined: These are on a permanent foundation, usually there is a center beam in the attic or crawlspace. These often have hinged roof trusses, a visible marriage-wall. These also have a data plate. These have a third-party certification label though this might be inaccessible. The rest of this article is concerning manufactured homes and not modular homes.

Inspection of Manufactured Homes – Know Who The Regulatory Agencies Are

HUD governs all regulation but delegates much of the regulatory to other agencies. DAPIA (Design Approval Primary Inspection Agency) is responsible for plans, specs, quality assurance. Often the DAPIA is hired by the manufacturer which can create a conflict of interest; one reason why home inspectors should be hired when purchasing either a new or used manufactured home. IPIA (Plant Inspection Primary Inspection Agency) kind of code inspectors for manufactured homes. They walk through the plants monitoring operations. They can shut manufacturing down. These can be private companies or state agency. If not state administered, the IPIA is hired by the manufacturer. SAA (State Administrative Agency) is responsible for handling consumer complaints. These are HUD approved. Most states have an SAA. Dealers are obviously the agencies who sell the sell manufactured homes.

This Part Is For Professionals Only…

General Requirements

The following are a list of things inspectors should look for; however it should be noted that these may or may not have been enforceable when the MHU was built, or in the particular municipality where the home is located. So this information should be used as general guidelines to identify “real” problems or to notify the homeowner or buyer of potential construction and installation issues.

  • Look for electrical bonding at the frame or chassis in the crawlspace. If the unit is a double wide, both sides of the frame should have a bonding wire attached.
  • At the marriage wall seen usually in the crawlspace or attic, the mating line should not have a gap wider than 1/2 in. The mating line should be bolted together.
  • Also, it is required to remove the tow hitch and wheels from the MHU after installation. (in my experience this is often neglected, or the tow hitch is disconnected and left in the crawlspace.)
  • Check for a data plate and verify the correct wind zone, heating zone, snow load of the roof, etc. (a date of the MHU can sometimes be located inside the toilet tank)
  • If you see planters installed against the outside wall, check for moisture damage and other issues.
  • Look for improperly installed pier blocks; installed sideways, wood pads thinner than 1 1/2 in., too many wood pads, leaning, failed, etc.
Here is some information to determine the age of the MHU if no data plate or dates can be found

1960’s: MHUs were built with a ridge beam along the center of the roof, they had aluminum siding, often have a side porch called a “cabana” which should always be independently supported and not connected to the structure. This cabana can even be constructed and used for habitable space as long as there is no kitchen.

1970’s: These units typically have 4 tie-downs at each corner of the unit (whether these have been installed or not is another matter; check for this). These were generally built using polybutylene piping. Definitely check for this and flag this in your report if present. This piping has been such a problem in MHUs that in my experience it is more common than not that the piping has either been totally replaced and partially. Also advise the buyer that this often makes the home uninsurable. Also MHUs built at this time usually have an 85 amp electrical service. You’ll notice a lot of pressboard used in the construction, acoustic tile ceiling, and wood wall paneling is common. A Ramada serving as a second roof or sort of carport were sometimes installed in the 70s.

1980’s: You’ll generally notice tie-downs every 8′-10′ in this time period. You’ll see particle board used, and canvass roofs were very common. One issue to look for on these roofs is exposed fasteners and loose seams.

1990’s: MHUs start to look much more like single family homes. Things to look for on these and newer units; document if strapping is not installed. There should be a vapor barrier on the ground in the crawlspace or covering the underneath of the floor framing. Document if this is missing or damaged. The ground in the crawlspace should NOT be completely level; it is required to have a ridge in the middle under the MHU, or sloping grade with swales.

Other requirements after 1990: When these units are installed, 6 soil samples are required to determine the soil load bearing capacity. Tie downs are required and are to e installed at a 45 degree angle from the I beam in the crawlspace. There is a buckle on these straps that should be exposed but the footer pads should not be exposed and should be embedded in the ground.

General pier installation requirements: Keep in mind that the manufacturer installation instructions may differ somewhat on this so we can’t be to dogmatic when reporting on this.

  • Piers generally should not be more than 36 in. high and should not lean more than 1 in.
  • A wood pad is required at the top of the pier blocks. If wedges are used, they must be doubled, not a single wedge. Only one 1 1/2 in. lumber member can be used. Multiple 1 1/2 in. boards is usually not permitted though this is very common.
  • Piers must be installed within 2 feet from the ends of the MHU and must be installed every 8 feet or less.


HUD Codes To Look For

Here is the current version of the HUD codes that can be referenced and even completely read through. HUD regulations preempt all local regulations regarding components that are installed at the factory, or are installed within the MHU after factory assembly. Components installed within a MHU must be listed for MHU use. This includes appliances, HVAC, etc. This should be checked if the MHU has been updated or remodeled. The home inspector can mention what has been replaced or upgraded so that the buyer can do research to confirm that the component is listed by a standards agency as approved for MHU installation. This is way beyond the scope of what can be performed by a home inspector. Technically, if it’s not listed, it is not legal. This could possibly be unsafe, especially for fuel burning appliances.

Outbuildings, landings, stairs, decks, anything installed outside the MHU is subject to local code. 24 CFR 3280 is HUD code and is similar to the IRC but is often far behind. 24 CFR 3282 provides rules for handling consumer complaints. 24 CFR 3285 provides minimum installation standards. Each MHU is supposed to have a book of manufacturer instructions which contains the installation instructions. This is the final authority of installation instructions. Alternative construction is permissible when approved by the DAPIA and accepted as a variation of code requirements by HUD. There are also Interpretative bulletins that can change application of code.

24 CFR 3280 Codes For Home Inspectors To Lookout For During Inspection of Manufactured Homes

3280.103Whole-house mechanical ventilation is required which is ahead of IRC. This must be part of the HVAC system. There is supposed to be a whole-house ventilation label. Kitchen and bath exhaust MUST exhaust to the exterior. NO RECIRCULATING FANS PERMITTED.

3280.105 exterior doors are permitted to be narrower than typical residential construction at a minimum of 28 x 72 which is smaller than IRC. 3280.106 – Window egress requirements are that the window sill is no higher than 36 inches off the floor, no minimum window size is required for egress.

3280.204 Upper cabinets within 6 inches from range must be covered with 5/16 gypsum board; 24 inches minimum clears from top of range cook top is required for cabinetry. 3280.205 – No carpeting allowed in furnace and water heater room. 3280.209 Smoke alarms must be within 20 feet of a cooking appliance. Plumbing code is very similar to the IRC.

3280.707 – Heat producing appliances must be listed for use in MHU. Look for that on the data-plate of the appliance. 3280.708 – There is no requirement for smooth-wall dryer ducting but dictate that the dryer vent cannot terminate under the MHU. 3280.709 – Combustion air from inside the MHU is not allowed. The exception is cooking appliances and clothes dryers. Gas appliances must be direct vented to the exterior. This includes solid fuel appliances. These must have exterior combustion air, a spark arrester is required and these units must be secured. Water heaters require a drip pan to be installed underneath.

3280.801-805AFCI protection is not required. A four wire plug cord can be used as a feeder wire to connect a manufacture home. It should be noted that NO ALUMINUM BRANCH WIRING is permitted. Even multi-strand aluminum is not permitted to be used in a manufactured home. A single electrical disconnect is required for MHUs. 3280.809 – The main service panel neutral and grounds can be connected but ARE NOT TO BE BONDED TO THE PANEL BOX. The neutrals and ground wires can be connected even in the subpanels but the boxes should not be bonded. Also, bonding jumpers in cooking units and clothes dryers must be removed from appliances. Though inspectors do not verify this, this can be noted for the home owner to have evaluated. The chassis or frame of the MHU must be bonded with a #8 copper wire. Metal pipes, ducts, metal roofing and wall cover is all required to be bonded.

24 CFR 3285 HUD Code Requirements

Piers can be concrete block, treated wood, metal jack stands on adequate footings. A skirt is not required nor is a permanent foundation. This type of installation may not be eligible for FHA and VA mortgage loans. Leveling should allow the doors and windows to operate properly, (duh). There are flood mitigation requirements in flood zones. Notify the buyer to check on any requirements. MHU installation must conform to wind speed requirements.

3285.203Grading is required to slope 1/2 in. per foot for 10 feet away from the MHU. 6 mil polyethylene or similar vapor retarder is required if a permanent skirt is installed. 3285.305 – 12 in. or greater clearance from the ground to the lowest framing member. Piers over 67 in. tall must be approved by an engineer. Piers should be installed under the main frame and around the perimeter under exterior doors and any fireplace. 3285.312 – 4 in. thick concrete pads are permitted. 3285 Subpart E Anchorage – Diagonal straps required. 3285.603 – A pressure regulator is required if the water pressure is above 80 psi. One last thing to note is that manufactured homes will often have poor floor installation due to code directed installation.

For now that is all I have on the inspection of manufactured homes. This article and the link resources can work as a research index for find all you need to now about requirements governing manufactured homes. Here is one last resource that I find very helpful. I hope this is helpful to in your research; I use this in training my own team of inspectors. Coming to you from the South Florida Specialized Inspection Services of Michael Gaurnier, ACI.