Idaho's New ADU Law (SB 1354): What Changed, and What It Means for Tiny Homes

If you have been thinking about adding a small second home to your property, whether for an aging parent, a returning adult child, rental income, or just a simpler way to live, Idaho just made that a little easier. On July 1, 2026, Senate Bill 1354 took effect, and it is one of the more significant housing law changes our state has seen in years.

We want to walk you through what this bill actually does, in plain language, and just as importantly, what it does not do. There is a lot of buzz around SB 1354 right now, and some of it overstates what changed. So let's separate the real wins from the wishful thinking.

What is an ADU, anyway?

An accessory dwelling unit, or ADU, is a second, independent living space on the same lot as a primary home. It might be a basement apartment, a converted garage, or a small standalone cottage in the backyard, complete with its own kitchen, bathroom, and entrance. You may have also heard them called granny flats, in-law suites, or backyard cottages. If you are exploring a tiny home as an ADU, this is exactly the category of housing SB 1354 addresses.

What SB 1354 actually does

Before this bill, many Idaho cities could simply say no to detached ADUs, or bury them under so many restrictions that building one was not realistic. SB 1354 changes that for larger cities. Here is the short version:

• Cities with a population over 10,000 can no longer ban ADUs outright in residential zones.
• Those cities must allow at least one ADU per single-family lot, either as an internal unit or a detached structure in the rear yard.
• Cities cannot require the owner to live in the primary home or the ADU. That owner-occupancy hurdle, which used to trip up a lot of would-be buyers, is gone at the city level.
• Cities cannot force an ADU to be smaller than 1,000 square feet, or 75 percent of the primary home's size, whichever number is bigger. That is a floor, not a ceiling, and it is a meaningful protection for anyone worried about being squeezed into an impractical footprint.
• In most cases, cities cannot require extra off-street parking just because you added an ADU.
• Cities must approve qualifying projects administratively, meaning no lengthy discretionary hearings for a project that already meets the rules.

Affected cities have until February 1, 2027, to update their local codes, so there may be a transition period where some cities are ahead of others.

Who this law covers, and who it does not

This is the part that trips a lot of people up. SB 1354 only applies to cities with a population over 10,000. If you live in a smaller town, or in an unincorporated part of a county, this particular law does not create a protected right to an ADU on your property. Your local rules still govern, so this is one of those cases where it genuinely pays to check with your own city or county before you get too far into planning.

The honest caveat: this bill does not specifically allow tiny homes on wheels

Here is where we want to be straightforward with you, because we think you deserve a clear picture rather than a rosier one.

SB 1354 is written around the general concept of an accessory dwelling unit. It does not specifically address tiny homes built on a chassis and wheels, the kind that are titled and certified the way ours are, through the NOAH+ standard rather than conventional residential building code. Many city ADU ordinances were written with site-built or manufactured structures on a permanent foundation in mind, and this new state law does not force every city to treat a wheeled, NOAH+ certified tiny home the same way.

What that means in practice is that whether a tiny home on wheels can satisfy your city's ADU rules still comes down to your specific city's ordinance. Some cities already welcome certified tiny homes on wheels as ADUs. Others are more particular about foundation type. And that is a genuinely important point: cities are always free to be more permissive than the state minimum SB 1354 sets. The state law is a floor, not a ceiling, and plenty of Idaho cities choose to go further.

So why does this still matter?

Because it is a real, meaningful step in the right direction, even if it is not the whole staircase.

SB 1354 removes some of the biggest obstacles that used to stand between a homeowner and a second small home on their land: outright bans, owner-occupancy requirements, and undersized minimums. That is a shift in the right direction for anyone who wants to age in place near family, house a parent nearby, or simply live smaller and simpler. It also reflects a broader, encouraging trend. As more cities update their codes to comply, more of them are having honest conversations about what belongs in a residential neighborhood, and that conversation tends to open doors for tiny homes over time, even when a bill's fine print starts out narrower than we would like.

What we recommend

If you are considering a tiny home as an ADU, do not assume either extreme, that it is automatically allowed or automatically off the table. Call your city's planning department, ask specifically whether a certified tiny home on wheels can qualify under their ADU rules, and bring that answer to your free consultation with us. We will walk you through financing options, and match you with a floor plan from our models that fits your situation.

Idaho took a real step forward this year. Let's help you figure out exactly what it means for your address. Our zoning page covers what we know today.

Snake River Tiny Homes may provide general information to help buyers navigate local zoning and permitting questions, but this is not legal advice, and buyers are solely responsible for confirming compliance with their local jurisdiction.