Mr. Richard Coon

Recreation Vehicle Industry Association

P.O. Box 2999

Reston, VA  20195-0999


Dear Mr. Coon:

This responds to your letter asking about the meaning of the term “modified roof” in S3 of Federal Motor Vehicle Safety Standard (FMVSS) No. 226, “Ejection mitigation.”  The term is used in FMVSS No. 226 for purposes of determining the applicability of the standard, as “modified roof vehicles” are excluded from the standard (see S2, FMVSS No. 226). 

Your question relates to what you describe as “light motorhomes weighing less than 10,000 pounds (approximately 2,000 manufactured each year, in the aggregate).”  You describe various ways the roofs of these vehicles are modified by final-stage manufacturers[1] and ask if the resulting vehicles are “modified roof vehicles” under FMVSS No. 226. 

FMVSS No. 226 sets forth the following definition[2] of “modified roof.”  “’Modified roof’ means the replacement roof on a motor vehicle whose original roof has been removed, in part or in total, or a roof that has to be built over the driver's compartment in vehicles that did not have an original roof over the driver's compartment.”


We would like to begin our answer by stating that NHTSA evaluates possible violations of the FMVSSs according to the facts of each particular case.  Thus, we are unable to agree with your view that there is a sweeping exclusion from FMVSS No. 226 for “any motor vehicle roof where any part of the original structure has been removed by the final stage manufacturer” (your emphasis).  Such a pronouncement implies that merely cutting and plugging a tiny hole into the roof renders FMVSS No. 226 inapplicable, an implication with which we do not agree.  NHTSA would assess whether modifications made to a vehicle roof are bona fide.

 That said, in your letter you describe specific types of roof modifications performed by final-stage manufacturers.  You state:

Small motorhome roof modifications ...range from a complete replacement of the original roof, to partial roof removals and replacement with reinforcing structure and/or additions such as vents with moveable covers, exhaust or air circulation fans, rigid or moveable skylights, satellite dish or television antennae assemblies and rooftop air conditioning units.  Note that these a/c units—the most common source of partial roof removals—are not a part of the vehicular systems, are not tied into the vehicle’s climate control equipment and are intended to operate when the vehicle is stationary and functioning as temporary living quarters.  In fact, all powered equipment installed during the roof modification process also requires the installation of wiring to connect the device to a power source, such as an electrical hookup at the camp site or a generator.  This equipment, and the roof modifications required for their installation, is critical to the vehicles’ camping and outdoor recreation function.

After considering the information you provide, we agree that vehicles with roofs modified in the manners you describe would be “modified roof vehicles” under FMVSS No. 226.  It appears such modifications would be made in good faith and not merely to circumvent the application of the standard.

Note, however, that the agency drafted FMVSS No. 226 to exclude modified roof vehicles because NHTSA was concerned about potential impacts of the standard on small entities, i.e., final-stage manufacturers and alterers, that may have to build out a roof or substantially affect the structure and design of the original ejection mitigation side air curtain system.  We would like to urge small entities not to needlessly disconnect or otherwise make nonfunctional ejection mitigation systems that they encounter when producing their vehicles.  If it is possible for them to modify the roof of vehicles that have an FMVSS No. 226 ejection mitigation system without negatively affecting the safety system, we encourage them to do so.  In that way, the modified vehicles would continue to provide the ejection mitigation protection of FMVSS No. 226. 

Finally, NHTSA continues to evaluate the regulatory exception for modified roof vehicles to ensure that the highest possible levels of safety are achieved.  It may be necessary for NHTSA to revisit the current exception through the rulemaking process if it appears that modifiers are needlessly making ejection mitigation systems nonfunctional. 

If you have further questions, please contact Deirdre Fujita of my staff at (202) 366-2992. 



Paul A. Hemmersbaugh

Chief Counsel


Dated: 3/22/16

Ref: Standard No. 226

[1] You state that RVIA represents “manufacturers and component part suppliers of all recreation vehicles, including motorhomes (‘RVs’).”

[2] Note that this definition differs slightly from the one you quoted in your letter.  The definition you quoted was amended effective Oct. 9, 2013 (78 FR 55138, Sept. 9, 2013).