I recently joined the International Code Council’s (ICC) IS-OSMTH (International Standard for Off‑Site Construction — Modular Tiny House) committee as an interested party to the development of ICC 1215: Design, Construction, Inspection and Regulation of Tiny Houses for Permanent Occupancy. As a tiny home owner-builder myself, I’m excited about the prospect of helping tiny homes gain legitimacy in the marketplace, and a standard like ICC 1215 could provide a pathway for local jurisdictions to more easily adopt tiny house friendly policies while maintaining reasonable standards for safety.

After sitting in on my first meeting, it became apparent that there were some significant tensions between some of the interested parties and committee members and the rest of the committee regarding a change to the initial standard proposal which expanded the scope of the standard to include a new category of housing called the “Small Residential Unit” (SRU) and placed tiny houses under that. SRUs are defined in the draft standard as including homes up to 1200 sq ft, or 3 times the 400 sq ft max that currently defines a tiny house under the International Residential Code’s (IRC) Tiny House Appendix.

Several interested parties have brought up the fact that this change was made possibly in violation of ANSI procedures and that concerns and complaints about this change, when voiced, were repeatedly ignored, leading some to question the entire process and motivation behind the standard. 

As an outsider to this process, I don’t want to unfairly judge anyone’s hearts or motivations. Some committee members, including Zack Giffin (of Tiny House Nation), have argued that the 1200 sq ft standard allows for flexibility in building tiny homes consisting of multiple units on separate chassis configured into a single home, but so far the standard is silent about this possibility or any further considerations it might require.

My own concerns come down to:

1. Making sure the standard fills its intended niche in a way that makes it easily adoptable (and doesn’t get thrown out or ignored by jurisdictions due to overlap and confusion)
2. Keeping the market for tiny homes affordable, fair, and open to small artisan builders and owner-builders.

I believe that the 400 square foot tiny house designation is relevant to these concerns, and I outlined my reasons in a comment sent to the ICC last week, which I’ve included here. Ultimately, I hope that these concerns can be addressed and we will have a standard that everyone can get behind. 

You can sign the petitions and learn more here:

• Petition by Janet Thome of Tiny House Alliance USA (Contains helpful background & links)
• Petition by Macy Miller (owner-builder & architect) 
• New blog by Macy (Good overview)

PINS Concern Regarding ICC 1215

I am submitting this comment in response to the revised PINS from May 16th, 2025 for ICC/THIA 1215-202x: Design, Construction, Inspection and Regulation of Small Residential Units and Tiny Houses for Permanent Occupancy.

The revised scope — covering residential units up to 1,200 sq ft — appears to duplicate and potentially conflict with existing ICC and federal standards, including:

• IRC, which already applies to homes of all sizes off-chassis
• HUD Manufactured Housing Code, which covers homes on chassis over 400 sq ft
• ICC 1200/1205, which apply to off-site construction

This lack of a clearly bounded scope introduces ambiguity and contradicts ICC’s responsibility to minimize conflict and overlap among its standards.

In particular, including homes well over 400 sq ft could:

• Dilute the effectiveness of the standard for truly small homes on chassis under 400 sq ft, which are currently not covered by an existing standard
• Create confusion for jurisdictions and inspectors already tasked with navigating IRC, HUD, and modular guidelines
• Overburden small builders and owner-builders, who are a primary stakeholder for tiny houses

Tiny homes under 400 sq ft present significantly lower structural and life safety risks than larger homes. This has important implications for:

• Regulatory burden (allowing a lighter regulatory touch)
• Affordability & housing access
• Owner-builder and small-scale builder feasibility
• Transportability on a chassis
• Reduced utilities requirements
• Greater design flexibility within the prescriptive code

In addition, “Tiny House” is an established and defined term within the IRC Tiny House Appendix. In contrast, the term “Small Residential Unit” (SRU) is a brand new term, encompassing a wider range of building types and stakeholders. The original intent of ICC 1215 appeared to be to provide a permanent chassis option specifically for structures already covered by the Tiny House Appendix, addressing a gap not covered by off-site or modular standards like ICC 1200 and 1205. Expanding the scope to include all SRUs up to 1,200 sq ft blurs the lines between these distinct groups, risks stakeholder confusion, and duplicates coverage already provided by existing ICC codes and federal standards.

I suggest that ICC 1215 either:

1. Limit its scope to homes 400 sq ft and under, or
2. Clearly divide the standard into separate tiers or sections, so that smaller homes are not subject to the same requirements as larger SRUs.

This will preserve the purpose, clarity, and usefulness of the standard — especially for jurisdictions and owner-builders seeking a practical, code-aligned pathway.

Sincerely,

Mike Spooner

Tiny Home Owner/Builder
Teaspoon Dwellings

Also of note: ASTM International also has created a subcommittee for developing tiny house standards. ASTM’s initiative began before ICC decided to develop their own standard.

I wanted to share some exciting news that I’ve had some involvement in on the tiny house codes and standards development front!

Some Backstory

Ever since the tiny house movement started picking up steam, tiny homes have existed in a confusing legal grey area. Manufactured/mobile homes are regulated through the HUD code for full-time living, while recreational vehicles have their own standards as temporary living quarters. Tiny homes, however, fall somewhere between. They are smaller than manufactured/mobile homes, but unlike an RV, they are built for full-time living. They are also often owner built or built by small artisan builders who can’t afford the HUD pathway.

This is why back in 2016 a group of tiny home advocates, including Andrew Morrison and Macy Miller (two of my inspirations when I was designing my own home around this time), participated in a successful effort to create Appendix Q of the International Residential Code (IRC). This created a realistic pathway for homes under 400 square feet to be built. Most jurisdictions in the US use the IRC, so this allowed jurisdictions everywhere to easily adopt this new code.

At the time it was written, the advocates had intended to include provisions for the trailer chassis in the appendix. Unfortunately, this was determined to be too much of a lift and the chassis language had to be scrapped in order to ensure that the appendix could be approved. This meant that Appendix Q really only applied to tiny homes on a traditional foundation.

RB42-25-1: A Second Chance for the Chassis

The intention was always that the chassis (tiny homes on wheels) option could be revisited in a later revision of the appendix. Well, that time is NOW!

Macy Miller has reunited a group of advocates, including Martin Hammer and David Eisenberg, who were both instrumental in making the original tiny house appendix a reality (and have advocated very effectively for a variety of other alternative building techniques) to back a code change comment (RB42-25-1) that would add chassis provisions to the tiny house appendix (now called Appendix BB). The exact language of the code change comment can be found here. There is a real possibility that this proposal could pass. If it does, it will finally give jurisdictions the tools they need to start zoning for movable tiny houses.

If you’re reading this right now and have ever thought about living in a tiny home yourself, want to see more pathways to more affordable housing, or if you simply believe that people should have the option to live in whatever way they choose, please consider signing this petition to show your support!

While this code change would create a long overdue legal pathway for movable tiny houses on wheels, it would not include prescriptive details for attaching the home to the chassis or temporary foundations for securing these homes to the ground (at least for the time being). Instead, it requires engineered designs for these aspects of the home. This leaves room for some of the other standards efforts going on right now that I’ve been involved in–the ASTM E06.26 tiny house subcommittee and the ICC/THIA 1215 standard–to hopefully fill in some of those gaps.

A big thanks to Macy Miller for her steadfast advocacy for DIYers in the space of code and standards development and for giving me an opportunity to contribute feedback during the development of the language for this proposal. I’m grateful and excited!

Take Action

• Read more on MiniMotives
• Read the full code change comment
• SIGN THE PETITION!

RB-42-25, the Tiny House IRC code proposal I posted about back in September aiming to codify movable tiny homes in the International Residential Code, unfortunately did not pass at October’s hearing. Since then, Macy Miller and her team have been working behind the scenes to identify any remaining path forward in this code cycle.

There is one final opportunity this April at the Public Comment Hearing, which will be at the Connecticut Convention Center in Hartford, CT. It’s a high bar—requiring a 2/3 majority vote of the full voting body. If we don’t make progress this cycle, the next opportunity won’t be until 2030.

I’m happy to report that I am signed on as an official co-proponent on the proposal this time around, and–if all goes according to plan–will be testifying at the hearing along with an amazing group of fellow tiny house owners and advocates.

Can you help?

To have a chance, we’ll need a nationwide outreach effort. We’re organizing support from people willing to contact building officials. We’ll provide clear guidance, templates, and step-by-step instructions when the time comes.

• Sign Up for our Mailing List - Stay connected to the code effort. We’ll keep you posted on exactly when and how you can help.
• Donate to the Fundraiser - Help with travel expenses to bring advocates to the hearing.
• Sign the Petition - If you haven’t already done so, please add your name to our petition. (Don’t donate here–just sign the petition)

Still confused as to what this is all about? Read the FAQ. My last post should also help you get you up to speed.