Posts Tagged ‘footings’

OMHC Approval of ABS (Pier) Pads

May 10, 2011

On April 20, 2011, the Ohio Manufactured Homes Commission (OMHC) held a hearing on proposed changes to Ohio Rule 4781, which governs installation of manufactured homes in Ohio.  One change to those rules was to allow ABS pads as footings for  manufactured homes.  The exact wording is as follows:

“ABS footing pads shall be permitted if used in accordance with the manufacturer installation instructions and/or specification sheet of the specific ABS pad being used.  The use of ABS pads must be used in conjunction with solid perimeter skirting in accordance with paragraphs (D) (1) to (D) (4) and (E)(1) to (E)(6) of rule 4781-6-02.5 of the Administrative Code.”

We attended this hearing specifically to voice concerns about this revision to the previous rules that did not allow these pads.  Three ABS pad manufacturers, Oliver, Polyvulc, and Tie-Down Engineering, also spoke at the hearing in favor of the changed rules.  Our assessment of the attitude of the OMHC during the hearing was that it favored the rule change.  Therefore, we wrote the letter attached to this blog post and submitted it to the OMHC within the comment period (less than 24 hours).  That letter is included here:

OMHC Has Approved ABS Pads For Manufactured Homes

We found later that the OMHC had indeed passed the rule change, allowing ABS pads.

As the letter states, we are concerned that ABS pads will be used in conditions where they are not intended.  Although the rule change states that the installer must follow the manufacturer’s installation instructions, we had reviewed the instructions of the three main pad manufacturers and found them greatly lacking in detail, and where there is a lack of detail, there is opportunity for misuse.  In a conversation with two of the manufacturer’s representatives after the hearing, we were informed that other states that have allowed ABS pads also have training sessions particularly for ABS pads.  Our feeling is that if ABS pads are allowed, they need to have such required training additional to following the manufacturer’s instructions.

Essentially, our concern is that ABS pads require that soil be used as a replacement for concrete footings or slab.  Granted, some soils can be “hard as concrete” when at certain moisture content and without organic matter and voids.  That is to say, the soil has the same bearing capacity as concrete.  However, unlike concrete, which has a bearing capacity that changes little over a wide range of conditions, the bearing capacity of soil can change dramatically.

Therefore, if soil is going to be used to replace concrete, the soil conditions must be controlled.  In the one decently documented case where ABS pads were successfully used, soil moisture and frost heave were well-controlled.  In this case, insulated skirting to maintain temperatures above freezing in the crawlspace and drainage around the home’s perimeter were used.  The manufacturers’ installation instructions usually state a minimum required  soil bearing capacity and that the pads be placed “at or below the frost-line”.  The insulated skirting, moves the frost line to grade.  The required soil bearing capacity is in part essentially a requirement for proper drainage because the soil bearing capacity can drop significantly as the soil moisture increases.  Thus, soil moisture needs to be controlled through proper drainage.

But, can installers be trusted to measure soil bearing capacity accurately or to accurately calculate whether an ABS pad be able to take the weight put on it?  Can most inspectors be trusted to check the right parameters and review the required information.  The OMHC has left those questions wide open.  Currently, installers and inspectors are not required to have special training.  Therefore, no two installers will be doing the same installation or checking the same parameters.  That is why we wrote the letter to the OMHC.  If ABS pads are going to be used, they need to be used properly and uniformly.  They cannot simply be used in place of concrete footings because soil is not exactly the same as concrete and the weight being put on the soil will usually be more for ABS pads than for concrete footings.

We are going to continue pursuing the issues of proper training for ABS pad use.  We are also aiming for the requirement that a licensed engineer approve the use of ABS pads to assure that homeowners get the home that they believe they are buying.  In a future blog, we plan on commenting research sponsored by the Ohio Manufactured Home Association which has been used to back the approval of the pads.  Stay tuned.

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It’s just an ABS pad, right?

November 24, 2009

This past week, the Ohio Manufactured Home Commission held a hearing on revised changes to Ohio Rule 4781.  This law is the one that dictates among other things how manufactured homes are installed in the State of Ohio.  If you install any manufactured home in Ohio, whether you are moving the home from one place to another or purchasing it new, or whether it is being installed in a manufactured home park or on private property, this law is the one that the installers and inspectors must follow when installing it.  Interestingly, most manufactured home owners are not even aware of it–until they move the home and try to have the power hooked up.  That is when the power company is going to ask for proof of the required inspections.

The changes in the rule were initiated to align it with the federal Housing and Urban Development (HUD) model codes, which dictated the minimum requirements for all states’ laws.  Ohio initially developed its rule before HUD finalized its model code, by more than a year.  However, when HUD’s model code was passed into law, Ohio needed to align its rules with HUD’s, and that was the purpose of the hearing.

One particular part of the rule change had me concerned.  It was the part where acrylonitrile butadiene styrene (ABS) pads were going to be allowed for all installations in place of a concrete footing required in the current rule.  The foundations of many manufactured homes differs from stick-built homes in that the home is supported on a series of piers as opposed to a wall foundation.  Typical manufactured homes have a pair of steel I-beams running the length of each section of the building.  When set, these beams will sit atop the piers, which are spaced about eight to ten feet apart.  Some manufactured homes do have foundation wall structural systems.  But, even these homes have a series of piers under the home in places.

Piers supporting a manufactured home are usually constructed with some kind of footing and a stack of concrete and wood blocks.  Until now, footings were a minimum of 6″ of concrete and usually were constructed in strips that either ran the length of the home or across the width of the home.  These footings were also required to be at frost depth, which is 30″ in our area.  Additionally, footings that are installed for concrete block perimeter walls for homes that have them are tied together with strip footings that run across the home’s width.  Tieing all of the footings together makes for a very solid foundation base.

The proposed rule change would allow ABS pads to be used in place of concrete footings for ALL installations.  So, what is an ABS pad.  They are a square or oval ABS plastic pad, that is about 1/2″ thick.  The dimensions of the pad that is used depends on how much weight the soil can bear.  Whereas, with concrete footings, a trench needs to be excavated, forms possibly installed and the soil compacted, ABS pad only require the lot to be cleared of debris and vegetation, reasonably leveled, soil compacted if needed and then piers erected.  Do these two installation even sound equivalent?

We at Criterium-Cincinnati Engineers did not think so.  In fact, we know so based on inspections of over 500 manufactured home installations that are qualifying for FHA loans.  These were homes with all kinds of foundation systems, on all kinds of soil types, in many different topographies and both single and double-wide structures.   I was there to try to persuade the cognizant Commission to leave the rule the way it was with NO ABS pads allowed.  Our conviction was that allowing ABS pads was not good for home owners who would not know otherwise.

Although I could not find any logical explanations for why the pads were being allowed, I have heard over and again the term affordable housing.  But, is housing affordable if the structural system fails due to the foundation sinking into the soil?  When this happens, the homeowner could either lose his or her investment in the home or incur large expense to fix the home.  In our opinion, affordable housing should be sensible affordable housing.

Surprisingly, I was the only one to testify against the ABS pads.  With the support of a couple of Commission members, who surprisingly are installers, the Commission voted to at least not allow pads to be used for all multiple section homes unless they are being temporarily set.  ABS pads will still be allowed for single-wide homes, not matter whether they are installed in parks or on private property.  We did not get a full victory; but I am happy with the result.  Multi-section homes are those purchased for long-term housing where the homeowner expects the property to gain in value.  Once set, these homes will likely not be moved, whereas single-wide homes often get moved.

And that is where the rule is at.  I, once again solely, applauded the Commission after the vote for their good work.


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