Let’s Talk About Slabs

In April, 2016, HUD announced that their installation program contractor (SEBA Professional Services, LLC) was preparing a report that would establish the design criteria for frost protected shallow foundations for manufactured homes. When the report was made available last October, it caused quite a stir from the various trade associations, as well as several members of the Manufactured Housing Consensus Committee (adviser to HUD on code and regulatory issues).  The plan was that HUD would use this foundation report as an installation standard that would basically become the bible on design/construction of slab style foundations.

Personally, I am of the opinion that HUD is over stepping its authority and that these types of site specific issues are best addressed by the state or local code enforcement authority. But since the discussion has been started, it might be a good time to take a closer look at a slab type foundations for manufactured homes and how they protect against frost heave.

Typically, in the northeast, we see two types of slab foundations:

1.       A slab on grade, also known as a floating slab (being constructed below). Very likely to shift as a  result of ground freezing. Not recommended!



2.    A frost protected slab (pictured below) where the site is excavated with the slab poured below the finish grade and a masonry wall constructed around the perimeter which is back filled against. Since the slab is lower than the surrounding grade (to the approximate depth of frost penetration), it is unaffected by frost heave.  The masonry crawl space walls sometimes are used to carry steel cross-beams to support the home, but mostly the home is supported by piers inside the crawl space enclosure.


I reviewed several different manufactured home installation manuals, and could only find a handful that have designs for a frost protected slab foundations and they were all pretty similar. There are designs that depend on acceptance by the “local authority having jurisdiction”, and designs specific for the state of New York. My concern is that I have never seen a slab foundation being constructed anywhere close to the requirements listed in these designs. This article is intended to get professional installers thinking about frost protected slab design and construction. Here are a few things to consider:

Every foundation design demands that you determine the soil bearing capacity (SBC) at the site.  Most designs require a minimum SBC of 2000 pounds per square foot.   As the installer, you must have a good understanding of the soils in your area. Even though a 2000 SBC is fairly common, make sure that soil bearing capacity is being taken into consideration and documented on your installation check-list.

Next you need to look at the soil moisture content.  Many designs demand some type of determination that the average soil moisture content is less than 25% down to frost depth! Truthfully, I can’t see too many installers having the time or ability to make this assessment.

As you start excavating the site, remember the earth beneath the slab should be turtle backed, just like any other home site. And proper site grading around the perimeter of the home is a necessity (1/2” per foot slope all four sides)!

Next comes a minimum 6” thick gravel bed and 6mm poly vapor barrier under the slab which is an essential requirement common to every manufacturers design I have seen. Often the perimeter of the slab generally is thicker (12”) than slab itself, and reinforcement (rebar) may be required.

Even taking these issues into consideration, there are still concerns of frost heave impacting slab foundations that are poured at grade (floating slabs). My primary concern hinges on the inability to maintain the temperature in the crawl space due to manufactured housing floors being insulated (no heat loss into the crawl space).

The frost protected slab where the site is prepared below grade (talk to your code official for the exact depth), a slab is poured, and a perimeter wall (or crawl space enclosure) is constructed that you can back-fill against seems to make better sense for manufactured housing. 

My experience is such that these “below grade” slabs work great. And even if it is not as deep as the maximum frost penetration, as long as it is close, it appears to works well.


One final thought; make sure your homeowners understand how rain water can impact the foundation regardless of its depth. Inform them about the importance of downspout splash blocks to direct rainwater away from the home. Warn them about landscaping timbers or decorative borders that can channel water towards the foundation (as was the case in the photo above). Watch for recessed decks or porches which can also be a huge problem (look for that in an future blog entry).

For more information on this topic, I encourage you to participate in the Pennsylvania Housing Research Center (PHRC) upcoming webinar ” Frost Protected Shallow Foundations in Pennsylvania”. the webinar will be presented on Tuesday, February 14, 2017 at 1:00 PM. If you missed it, the webinars are archived so you can still take advantage of this free educational opportunity. CLICK HERE to access their webinar.

Who Are THEY?

Trying to decide where to park at a large home improvement store the other day, I said to my wife “why did they make the exit door so far away from the entrance?”.

Driving home, after catching the third red light in a row, I wondered, “why don’t they synchronize these lights better?”.

The afternoon mail made me ask, “why do they keep sending me all this junk mail?”.

This brings me to the real question, “who are THEY”?

When it comes to Manufactured Housing codes, rules and regulations, THEY are the U.S. Department of Housing and Urban Development, Office of Manufactured Housing Programs (HUD-OMHP).hud

HUD-OMHP are a handful of folks that work in a huge government agency. And truth be told, an agency where manufactured housing is not always a priority. THEY, don’t know many installers, but I think THEY would benefit from connecting with you and hearing from you. And, THEY have made it pretty easy.

I encourage all manufactured housing professional installers to visit the HUD-OMHP web site. There are a couple of pretty important things you can do there:

  1. Get on the mailing list for the newsletter, “The FACTS”, and check out some past issues.
  2. Click on the “Highlights” section where you can access the HUD Code, Installation Standards, Dispute Resolution Program, and many other tools that are important to your success.
  3. There is even a place where you can send them questions or comments.

HERE is a link to their web site. I think you will find it helpful, and THEY will appreciate it!

A Very Valuable Tool

When installing manufactured homes, which tool is the most valuable?

I don’t mean your bottle jacks, come-along, air compressor or sledge hammer.  I mean the tool that will protect you in case a homeowner decides to sue you for a faulty installation.  Or should they file a complaint against you under a State or Federal Dispute Resolution Program.  Which tool will you use to defend yourself?

In 2008, most home manufacturers started including a “Complete Installation Checklist” in their installation manuals. Today, I believe all manufacturers have these installation check lists. If you ever find yourself before a judge, mediator or arbitrator, you are going to wish you had a completed checklist as evidence that you did what was required to properly install the home.

OK, I know that these checklists are not perfect; in fact, they carry a disclaimer that they are “not all-inclusive”. But before we throw the baby out with the bathwater, let’s take a little closer look.


First of all, federal law requires that installers maintain records of manufactured homes they install for three years. What records do you keep? At a minimum, you should retain these documents for every new home you install:

  • The contract for the job (or at least a written scope of the work you are expected to complete)
  • A record of completion (a completed certificate, insignia log, or whatever your state or HUD requires you to do at completion)
    • Keep in mind, federal dispute resolution is applicable for problems reported in the first year. So, you need to clearly establish the date of completion
  • Several date stamped photos of the installation
  • Site specific information (soil bearing capacity, frost depth)
  • Installation details you followed (including anchoring system)
  • The “Complete Installation Checklist”

This checklist is evidence that you completed the minimum steps needed for a successful installation. That the foundation and anchoring systems are correct. That all assembly was properly completed. And most important, that you completed the required testing:

  • Smoke alarm
  • Tub/shower water temperature
  • Water supply
  • Drain line
  • Gas system (maybe the fuel supplier conducted this test-if so, get a receipt for your records)
  • Electrical-continuity/polarity/ operation

Completing these checklists can not only be used as a big part of your defense in a court room or other proceeding, but can also be used as a marketing tool. Use it to illustrate why your installation might be better than your competitors!

In short, should you have to defend your work because the homeowner hired a lawyer, or files a complaint with HUD or your state, a completed installation checklist can be the most important tool in your toolbox!

No More Complaining!

Seventeen years ago, I started complaining. Today, I decided to quit complaining and do something.

Complained that there was no way to share new technical information with manufactured home installers. Complained that the government wrote regulations about installer responsibilities and never even talked to an installer. Complained that as the installers responsibilities increase, their compensation stayed flat. Complained that there was no consistent resource for installers.

Today starts the first blog devoted for the sole purpose of educating and elevating manufactured home installers. It is hoped that this blog will become an important resource in spreading information with the hard-working folks that make their living installing manufactured housing.

I have made my career in manufactured housing, and after almost 30 years of training, inspecting, presenting and promoting, I have concluded that for this industry to succeed, it needs to do a better job communicating with installers. Something besides the mandatory training classes delivered by some government bureaucrat or from a computer screen.

So, here is my attempt at communicating with manufactured home professional installers on a regular basis. I hope that you learn something from my posts, and I hope you decide to follow this blog. Tell your friends. Give me feedback.

No more complaining!