Best ADU For · 2026
Best Guest House ADU: Which Model Wins
If you’re building an ADU mainly to host guests, the Five Five Five is the model to book. At 555 sq ft with 1 bedroom and 1 bathroom, it’s priced at $267,000 with a permitting budget already built in, and it’s built specifically for the job: a real bedroom, a real living area, and enough separation that guests feel like they have their own place, not a converted shed. It hits the size sweet spot for a guest house better than anything smaller or larger in the lineup.
The short version: For a dedicated guest house, the Five Five Five wins. It’s sized to feel like a proper home for visitors without turning into a second full-time rental unit, and its $267,000 price, permitting budget included, keeps it well under the larger family models. If your guests only visit occasionally, the Four Fifty studio at $180,000 is the budget-friendly alternative. If you want a guest house that can double as a rental income unit when nobody’s staying in it, size up to the Six Sixty at $287,000.
Why a guest house needs a different kind of ADU
A guest house has a different job than a rental unit or an in-law suite, even though the building itself might look similar from the street. Guests aren’t paying rent, so you’re not optimizing for maximum square footage per dollar. You’re optimizing for comfort during short stays: a bed that isn’t a fold-out, a bathroom that isn’t shared with the main house, a kitchenette or small kitchen so guests aren’t walking through your living room for coffee, and enough breathing room that a weekend visit doesn’t feel cramped by day three.
That means a true studio can feel tight once you’re hosting adult guests for more than a night or two, especially if you want a separate sleeping area. On the other end, a 2-bedroom, 900-plus sq ft unit is more home than most people need for a guest house, and it costs a lot more to build and permit for space that sits empty most of the year.
The sweet spot is a real one-bedroom layout: enough separation between the bed and the living area that it doesn’t feel like a hotel room, a full kitchen or kitchenette, and its own bathroom, all in a footprint that doesn’t eat your whole backyard or blow past what a guest house actually needs to earn its keep.
The models that fit
| Model | Size | Beds/Baths | All-inclusive price* | Why it fits |
|---|---|---|---|---|
| Four Fifty | 450 sq ft | Studio / 1 bath | $180,000 | Lowest-cost option for occasional guests who just need a private place to sleep |
| Five Five Five | 555 sq ft | 1 bed / 1 bath | $267,000 | The purpose-built guest house: a real bedroom with room to breathe, sized right for visitors |
| Six Sixty | 660 sq ft | 1 bed / 1 bath | $287,000 | The all-rounder, most popular model, best if the guest house may become a rental down the road |
*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.
All three are rectangle-footprint builds, which keeps the factory build and crane delivery straightforward and helps keep the timeline to about 5 months for any of them.
The top pick: Five Five Five
The Five Five Five was built with this exact use case in mind. Framework First’s own guidance on this model calls it out for couples, long-term tenants, and a guest house with room to breathe, and that’s precisely the balance a good guest house needs. At 555 sq ft, there’s enough distance between the bedroom and the main living space that it doesn’t feel like a studio, but it’s not so large that you’re paying for square footage your guests will barely use.
At $267,000, the price already includes a permitting budget, plans, foundation, the factory build, delivery, utility hookups, appliances, and final inspection. Your exact permit costs are set by your city and confirmed during your feasibility study, so there’s no guesswork left by the time you sign. And because it’s built roughly 97% in the Salinas, CA factory before a one-day crane delivery to your property, you’re not living through months of a construction crew in your backyard while it comes together. Plan on around 5 months from start to move-in ready.
If your guests are parents visiting for a week, adult kids home for the holidays, or friends staying while they house-hunt in the area, the Five Five Five gives them a place that feels like their own home instead of a bonus room with a bed in it.
The runner-up: Six Sixty
If you want more flexibility, the Six Sixty is the smart step up. It’s Framework First’s most popular model for a reason: at 660 sq ft with 1 bedroom and 1 bathroom, priced at $287,000, it’s built as the all-rounder that works for rental income, aging parents, or adult children, in addition to guests. The extra 105 sq ft over the Five Five Five buys a bit more living space and storage, which matters if guests tend to stay for extended periods, or if you want the option to rent it out on Airbnb or to a long-term tenant when you’re not hosting.
The tradeoff is $20,000 more upfront for that flexibility. If you know this unit is staying a dedicated guest house long-term, the Five Five Five is the tighter fit for the money. If there’s a real chance you’ll want rental income from it someday, the Six Sixty is worth the difference.
For guests who only visit a few times a year and don’t need much space, it’s also worth looking at the Four Fifty: a 450 sq ft studio at $180,000, the lowest price point in the lineup. It skips the separate bedroom, but for short, occasional stays it does the job at the lowest possible cost.
Pricing, financing, and next steps
Every model above already has a permitting budget built in: no separate contractor bids, and no scrambling to add appliances after the fact. Final permit costs are property-specific, set by your city and county, and confirmed during your feasibility study, and any site work like septic or retaining walls is handled in-house under your contract rather than folded into the listed model price. Before you commit to a model, run your numbers through the ADU cost calculator to see how the price fits your budget and financing plan, and check pricing to compare all 14 models side by side.
If you’re not sure whether your lot can support a 555 or 660 sq ft build, start with a feasibility study. It confirms what’s actually buildable on your property before you lock in a model, so you’re choosing based on what will work, not just what you like on paper.
Frequently asked questions
What size ADU is best for a guest house?
Around 550 to 660 sq ft is the sweet spot for most guest houses. That’s large enough for a real one-bedroom layout with a separate living area, but not so large that you’re paying for space that sits empty between visits. The Five Five Five (555 sq ft) and Six Sixty (660 sq ft) both fit this range.
Do I need a full kitchen in a guest house ADU?
It depends on how often you host and for how long. Both the Five Five Five and Six Sixty include a full kitchen as part of the build price, permitting budget included, which makes longer stays much more comfortable for guests since they’re not relying on the main house for meals.
Can a guest house ADU also earn rental income later?
Yes. The Six Sixty is built as an all-rounder specifically because it works well both as a guest house and, when you’re not hosting, as a rental unit. It’s Framework First’s most popular model for that flexibility. The Five Five Five can also be rented out, though it’s primarily suited to couples or a single long-term tenant.
How long does it take to build a guest house ADU?
The Four Fifty and Five Five Five are both about 4 to 5 months from start to a finished, move-in ready unit, since roughly 97% of the build happens in Framework First’s Salinas factory before a one-day crane delivery. The Six Sixty is also about 5 months.
Is a studio ADU big enough for guests?
For occasional short stays, yes. The Four Fifty studio at $180,000 gives guests a private place to sleep and their own bathroom at the lowest price point in the lineup. For longer or more frequent visits, a one-bedroom layout like the Five Five Five tends to feel more comfortable since it separates the sleeping area from the living space.
Ready to see what a guest house ADU could look like on your property? Start with a feasibility study or browse all 14 models to compare sizes and pricing.