“Tiny” Attributes for Broad Application in OSMC…

Below are thoughts related to ongoing efforts in terms of Appendix Q for Tiny Homes.

As a primary contributor for the IRC 2021 A.Q. effort, and a staunch advocate for its broad-reaching adoption (including here in Virginia), I remain a strong proponent for the exceptions it offers.

As such, I see great application for Appendix Q and other key attributes that have become “usual and customary” elements of the tiny home industry, even though such practices were derived from varied specifications held within the mostly residential (envelope and living spaces) and standards for recreational vehicles (which specifically apply to relocatable residential structures).

Here are a few related thoughts for your consideration:

• Incorporation of an Appendix – With regard to differences between AHJ requirements, there may be the need for the ol’ “where applicable” clause for cases like A.Q. as some states have adopted this appendix and others have not. California and Virginia are states that have specifically installed A.Q. as a statewide accommodation for use in site-built and modular home production. While A.Q. offers great relief, it may need to be viewed as elective within the OSMC. I bring this up to note how opportunity may be balanced against risk in terms of easing adoption of the OSMC standards that include A.Q. specifications.
• Purpose of Tiny-Sized Limit – It is my personal belief is that the term “tiny” is specifically rooted in some form of threshold that is best applied for considerations of floor area and (therefore) interior volume in terms of indoor air quality. The 400 sqft size was chosen as it is a (mostly historic) common point of demarcation between Recreational Park Trailers (RPT per ANSI A119.5) and HUD Code based units. For practical purposes, many producers of RPTs are already moving toward production of units otherwise deemed suitable only for temporary/recreational use. Such rec-to-res and/or dual certified units can be shown to meet AHJ code requirements for Residential structures through confirmation of meeting specifications in space design and (typically) adherence to site-based residential engineering requirements in the usual meet-or-exceed fashion. In my opinion, a Tiny Home definition can/should correlate with the IRC with its predominant attribute being it’s well established size limit.
• Leveraging A.Q. Attributes – While Appendix Q offers a series of exceptions, there are applications of such allowances that live beyond the tiny-sized 400 sqft max floor area. Exceptions for slightly lower main level ceilings, minimum loft height/area, use of alternate stair/ladder/ATV specs, and alternate means of egress have proven performance in the RV industry. Such accommodations bring a conformance to RPTs that can (and are) leveraged in Tiny Homes manufactured today as site-built, site-assembled, site-installed, and in an increasing number of inherently relocatable residential structures. While currently only available for Recreational Vehicles and in jurisdictions that have adopted (or otherwise allow) these accommodations, specifications in A.Q. offer great benefits to dwellings well beyond the tiny-sized footprint. Rather than expand the definition of Tiny Homes beyond the standardized footprint, I believe that A.Q. ceiling height exceptions and loft specifications have application for other modular dwelling types and may be held independent of the definition of a Tiny Home (i.e. same attributes may be used within various defined unit types).
• Dwelling Height Effect – Our perspective during the development of changes for the IRC 2021 code change cycle was to view A.Q. as applicable to “limited-size and height-restricted” residential structures. Such perspective expands the opportunities for permitting small-scaled residences, especially Accessory Dwelling Units, which are often limited to a size in floor area and total height as calculations derived from the existing primary residence (e.g. no greater than XXX sqft or XX% of primary residence floor area; not higher than 50% of existing roof; etc.). Having A.Q. allowances — where applicable — would be a boon for smaller residences that may be larger than tiny-sized proportions. The reasoning for independence of application of the attributes is the same as the above.
• Interior Air Quality – Tiny houses, small homes, and efficiency units span a broad range of sizes and heights, and therefore have smaller scaled interior volumes. Rather than view “tiny” as the only threshold, there is likely a need to establish a spectrum of sizes that vary in performance between smaller, average, and larger sized dwellings. Like span tables, the use of ranges, a table, or calculations may be necessary to define an application of size- appropriate air quality specifications, testing methods, and other design and inspection requirements. IRC 2021 Appendix Q may include an easy means of reference and/or guidance for development of OSMC specific standards for dwellings of varying sizes at the small end of the spectrum.
• Relocatable Residence – While the IRC/derivative specs seem mostly site-oriented (a world in which 1 1/2 story heights are of negligible concern), units produced off-site to Appendix Q for Tiny Houses offers big benefits in terms of transportability. This is especially true for delivery of dwellings without need for special permit for overheight loads. Whether the unit is turnkey or component (e.g. unfinished prefab shell), the voluntary application of A.Q. to “movable tiny homes” has been a major benefit for tiny home manufacturers, transport companies, and end users. In addition to Appendix Q exceptions, there are other common attributes of movable tiny homes that may be incorporated for the sake of safety and durability. For example, it is common to use H-clips and straps for the envelope to resist wind shear during transport that provides calculable metrics used to illustrate resistance to uplift when a unit is placed on a suitable temporary/permanent foundation and attached to ground anchors. The modular building and manufactured housing industries may be leveraged for applicable insights and specifications.
• Chassis as a Floor System – In keeping with the above, the tiny home industry has benefited in its use of a chassis not merely as a carrier of the dwelling unit, but the actual floor assembly. In essence, a typically wooden floor system is traded with a chassis for structure, insulation, and air transfer resistance. The reasoning is simple: If a unit needs more interior space while remaining code compliant, trading an I-beam based carrier (typical for RPTs and MHs) with an integral chassis as the main horizontal floor assembly gives back about a foot of interior height within an inherently vehicular structure. While the inclusion of an integral chassis grates against the conventional divide between permanent and temporary residences, I believe the tiny home industry has illustrated a meeting of market demand as coupled with a solution that simply seeks the legitimacy of qualification (what can be used), specification (to which parameters), and standardization (minimum qualifications that streamline design/engineering without the need for constant citation of alternate method or seeking of special exception). As for other common attributes of tiny homes, in my opinion this system can/should be readily available to a wide
  range of modular dwelling units.
• Alternate Utility Connections – Movable tiny homes are often tied to RV (“shore”) infrastructure, though some municipalities require direct connection to utilities. There are many situations where having the flexibility of an either/or setup is a great advantage. While on-board water/waste storage is heavily frowned upon in semi/permanent settings (read: largely disallowed), connection to power via suitably specified power cords offers great advantage to specific use cases. Of all the tiny industry items I am passionate about, this is the one that has the most alliance with RV-based park settings. I offer this as a point of consideration as shore power and water/waste connections are common in the tiny home industry, and standards for inclusion of such components is well documented and easily adapted in settings that may prohibit any form of temporary connections. In short, this offers advantages for select use (e.g. temporary disaster use converted to permanent accessory structure) and could be codified for application for select market/need, use case, and temporary/permanent placement. Here too, while the use of temporary utility connections is typical in the tiny home industry, such attributes are not intrinsically applicable only to movable tiny homes as relocatable residences. Here too, if allowed, what would be our standardized solution through the OSMC.

As a long-standing proponent for the viability of tiny-sized dwelling units and need to broadly qualify them through a meeting of specifications via proof of conformance, I believe the tiny home industry brings more to bear in OSMC than any one of its component parts. It seems that we could rather easily identify primary attributes (like those outlined above) for broader application within modular manufacturing.

Consider how the principle word — modular — suggests the viability of mix-and-match applications. When considering the OSMC as a means of legitimizing the use of component parts, varied specifications, and specific exceptions, I believe we have a unique and timely opportunity to legitimize various types of existing “no code” dwellings and heretofore undefined means of meeting ever-expanding use case/market needs for more flexible forms of housing product.