Are Your Designs Up-To-Date?

Just like last weeks lasagna in the back of your refrigerator, manufactured home installation manuals don’t last forever. Professional manufactured home installers must be certain that they are following the most up-to-date installation manual, which would be the one that was shipped inside the home being delivered from the factory. But how many manufactured home installers actually hold off their work waiting for the current installation instructions to arrive along with the home?

If you said “none” you are correct!

But there is no other process in place to provide manufactured home installers with the appropriate installation instructions. As a result, installers often are found to be using out-dated or obsolete designs, missing important installation requirements, or just installing every home the same way using the same techniques that they used years ago.

Additionally, far too many installers use engineered designs that might have been handed down from retailers, other installers, or some other random source. The problem is, all too often these engineered designs are outdated, and have been not accepted by the manufacturer and their design approval agency (DAPIA).

I have recently been made aware of a few manufacturers that have modified their requirements for a very common foundation/anchoring system. But most installers missed the change as there is no mechanism to keep them up-to-date.

Equally important, there is no way for an installer to know whenever a manufacturer updates their full installation manuals. Several manufacturers that have not updated their manuals since 2008. Others publish revised manuals almost as often as I change my socks!

But how can a professional installer assure that the details they use are the most current, besides waiting for the home delivery to start construction?

Keep in mind, that if you are the installer responsible for the overall installation of a new manufactured home, you are required to keep records for three years. These records should contain DAPIA approved designs, and details or instructions to clearly illustrate the entire installation process. Ultimately, you must be able to answer any questions regarding how the home was placed on the site by producing the design or instructions you followed. It is critical that you are utilizing the correct installation instructions!

Why not ask your manufacturers to start providing product bulletins every time there is a change to the installation instructions? These product bulletins could be sent to each retailer and maintained in a binder for regular access by installers.

I know that a few manufacturers have their installation manuals available on-line. Most notably:

Clayton, Click Here For the Site

Champion, Click Here For the Site

MHE, Click Here For the Site

Skyline, Click Here For the Site

This is a great idea, but it would be even better if installers could sign-up for email updates to keep them informed of any changes.

Ultimately, professional installers (and retailers) need to expect improved communication from the manufacturers. Start a dialogue with the Quality Assurance Manager or Engineer at the factory. Maybe there are some processes in place that you can utilize. If not, maybe he can develop a process to keep you informed.

Bottom line, you need to know that every home is properly installed, and following outdated instructions places you and the manufactured home in jeopardy!


Lately I have been running into situations where manufactured homes have been damaged as a result of excessive rust to the metal parts under the home. I am seeing reports of rust on the frames, gas lines and anchoring components. In my opinion there are two different sources of these problems; one is a problem with the installation, the other may be a potential problem with the design of the homes.

The installation problem that has been causing rust issues should be obvious; improper site grading. Compounding the issues of poor site grading, a home placed in a pit that collects water can accelerate corrosion of the metal parts under the home.

Pit set-area under the home is lower than the surrounding grade. Water fills the crawl space.


The rules for grading a manufactured home site are no different then site grading for any other home. The site must slope away from the home by ½” per foot for the first 10’. If needed, a swale can be cut into the ground but bottom line, you MUST grade the site to shed water. Flat sites are not acceptable. If the site cannot be properly graded, the home should not be placed there! I like to encourage installers to bring a few lifts of fill dirt to the site to allow proper grooming of the site.

Rusted frame in a pit set home.


However, there are still too many manufactured homes being installed in pits. What I mean is, the area under the home is excavated to be below the surrounding grade, and as a result it collects water. I can think of no better way to encourage rust than to place the home over a pool of water.

If you have no choice than to set the home in a pit, you should be constructing a masonry crawl space consistent with the state or local building code. This would mean a frost protected, damp proofed, perimeter wall that will prohibit water infiltration. Ultimately, keeping the crawlspace dry.

This crawl space is parged (damp proofed) to prevent water infiltration.

OK, but there is also another issue that seems to be contributing to the rust problem that is outside of the installation process. I am talking about recessed porches. It appears that in some cases, as water comes through the porch decking boards, it is leading to rusting of the frame in these areas. Keeping in mind that the frame must be able to transport the home for its intended life, these rusted frames can represent a failure to meet the HUD Code. We all know that the frame is painted to protect from rust and corrosion, but is it good enough in the porch area?

Decked porch lets rain drain onto the frame!

Frame under porch area with significant rust.


I know a lot of installers have begun using plastic shims (wedges) on the piers in the porch areas, as the typical hardwood shims have been rotting away as a result of water coming through the decking boards. I think this is smart!

Typical plastic shims


As a professional installer, be certain that the homes you install are placed on properly graded sites to allow water to drain away from the home.

If you happen to see, or if someone tells you about frames rusting under the porch area, be sure to report it to the manufacturer (regardless of warranty). Maybe in the near future, we will see a better way to protect these frames to improve the durability of the homes!