Best ADU For · 2026
Best ADU for Aging in Place: Which Model Wins
If you’re building an ADU so a parent (or you) can age in place, the Four Fifty is the model to start with. It’s a 450 sq ft studio at $180,000, built as one continuous room with no interior doors to navigate and no stairs anywhere on the lot. For most aging-in-place situations, less square footage to cross is the whole point, and the Four Fifty gives you that in the smallest, most affordable footprint Framework First builds.
The short version: The Four Fifty (450 sq ft, $180,000) is the easiest home to move around in because it’s essentially one room, which is exactly what a lot of aging-in-place buyers want. If a caregiver will be staying over regularly, step up to the Six Sixty (660 sq ft, $287,000) for a separate bedroom with more breathing room. If you want a defined bedroom door in the smallest possible footprint, The 405 (405 sq ft, $237,000) sits in between.
Why aging in place needs a different kind of ADU
Most ADU buyers are optimizing for rental income or square footage per dollar. Aging-in-place buyers are optimizing for something else entirely: how many decisions and how much distance stand between a person and the bathroom at 2 a.m.
That changes what “best” means. A bigger floor plan with more rooms sounds like more house, but for someone with limited mobility, more rooms usually means more hallway, more doorways to clear, and more distance from the bed to the bathroom. The goal isn’t maximum space. It’s minimum friction.
The other piece is who else is in the picture. Some families are building a home for one parent who’s fully independent and just wants a smaller, easier place to manage. Others are planning for a caregiver, a home health aide, or a family member who’ll be staying over several nights a week. Those two situations point to different models, which is why this isn’t a one-size answer even within a single use case.
The models that fit
| Model | Size | Beds/Baths | All-inclusive price* | Why it fits |
|---|---|---|---|---|
| Four Fifty | 450 sq ft | Studio / 1 bath | $180,000 | Fewest walls and doors to navigate, most efficient single room to move through |
| The 405 | 405 sq ft | 1 bed / 1 bath | $237,000 | A closed bedroom door in a footprint almost as small as the studio |
| Six Sixty | 660 sq ft | 1 bed / 1 bath | $287,000 | Room for a caregiver to visit or stay over without feeling cramped |
*Includes a permitting budget, not final permit costs. Permits and property-specific site work (septic, retaining walls, etc.) vary by property and are confirmed in your feasibility study.
Why the Four Fifty wins for most aging-in-place buyers
The Four Fifty is Framework First’s smallest model, and for aging in place, that’s a feature, not a limitation. There’s no hallway separating the bed from the bathroom, no second bedroom door to work around with a walker, and no wasted square footage that just becomes more floor to cross. Everything a person needs day to day is within a few steps.
It’s also the most budget-friendly model in the lineup at $180,000, permitting budget included, with the fastest build timeline at 4 months. For families who are adding an ADU specifically so mom or dad can move closer to the main house, that speed matters. You’re not waiting most of a year to get someone into a safer living situation.
The Four Fifty’s official best-fit use cases include first ADUs, small lots, aging-in-place, and a private studio for one, which lines up directly with what most single-occupant aging-in-place buyers are looking for: a self-contained, easy-to-manage home that doesn’t require reworking the whole backyard.
When to size up: The 405 or the Six Sixty
Not every aging-in-place plan is a studio situation. If the person moving in wants a true separate bedroom, whether for privacy, for noise separation, or just personal preference, The 405 gets you that in a footprint that’s barely larger than the Four Fifty: 405 sq ft, one real bedroom, one bathroom, at $237,000. It’s still a small, easy home to maintain and move through, just with a door between the sleeping area and the living space.
The Six Sixty is the right call when a caregiver is part of the plan. At 660 sq ft with one bedroom and one bathroom for $287,000, it has enough separation and living space that a home health aide or family member can stay over regularly without everyone tripping over each other. It’s also Framework First’s most popular model overall, which means it’s a well-proven layout, not an experimental one. If there’s any chance care needs will grow over the next few years, building a little extra room now is usually cheaper than adding on later.
All three models are single-level by design. Every Framework First model is built on one floor with no stairs inside the unit, so the aging-in-place question isn’t really “which model has no stairs,” it’s “how much space does this specific situation actually need.”
Pricing, financing, and next steps
All three models above already have a permitting budget built into the price, along with plans, foundation, the factory build, delivery, utility hookups, appliances, and final inspection. There’s no separate contractor bidding process to manage, though your exact permit costs are set by your city and confirmed during your feasibility study.
Before you commit to a model, it’s worth checking two things. First, run your numbers through the ADU cost calculator to see how a Four Fifty, a 405, or a Six Sixty compares side by side for your specific lot. Second, if you’re not sure your property can support an ADU yet (setbacks, utility access, lot slope), start with a feasibility study before you fall in love with a specific floor plan. You can also see current pricing across the full lineup if you want to compare against larger models before deciding.
Frequently asked questions
What’s the best ADU size for one person aging in place?
For a single person who’s largely independent, the Four Fifty (450 sq ft, $180,000) is usually the best fit. It’s built as one continuous room, so there’s minimal distance and no interior doors between the bed, the bathroom, and the kitchen. It’s also Framework First’s fastest build at 4 months and its most affordable model.
Do I need a separate bedroom for an aging-in-place ADU?
Not necessarily. A studio layout like the Four Fifty works well for many aging-in-place buyers precisely because there’s no bedroom door to navigate. But if the person moving in wants a closed-off sleeping space for privacy or noise reasons, The 405 (405 sq ft, one bed, one bath, $237,000) gives you a real bedroom in almost the same footprint.
What if a caregiver needs to stay overnight?
Step up to the Six Sixty (660 sq ft, one bed, one bath, $287,000). It has more living space and separation than the smaller models, which matters when a caregiver or family member is staying over regularly rather than just visiting during the day.
Are Framework First ADUs single-level with no stairs?
Yes. Every Framework First model, including the Four Fifty, The 405, and the Six Sixty, is built on a single level with no interior stairs. That’s true across the full 14-model lineup, not just the smaller units.
How long does it take to build an aging-in-place ADU?
The Four Fifty and The 405 both have a 4 to 5 month build timeline, and the Six Sixty is about 5 months. Since roughly 97% of the home is built in Framework First’s Salinas factory and then crane-delivered to the property in a single day, most of that timeline happens off-site while your yard stays undisturbed.
Can I add accessibility features to any of these models?
The Four Fifty, The 405, and the Six Sixty are all single-level, one-bathroom layouts with straightforward, open floor plans, which makes them naturally easier to adapt for mobility needs compared to a multi-room, multi-level home. Specific accessibility modifications should be discussed directly with your Framework First team during planning so they can be built into the factory process from the start.
Ready to see which model fits your lot? Start a feasibility study or browse the full model lineup.