Prefab ADU (accessory dwelling unit) vs Stick-Built vs Manufactured Homes
Factory modular ADUs vs on-site stick-built vs HUD (the federal standard for manufactured homes) manufactured homes: code, crew, schedule, and Wolf’s published cost ranges.
Home starting prices and your property
Home starting prices begin at $67,500 for Model B (City of Portland only).
Starting prices cover the home itself. Your property proposal covers the work needed around it.
Site work, foundation, utility connections, delivery, and installation are quoted for your property. Your written proposal defines the scope, taxes, appliances, and any additional work.
| Part of your project | How it is priced |
|---|---|
| Starting price for the home | $67,500 (Model B, City of Portland only) |
| Appliances and selected upgrades | Priced separately in your proposal |
| Permitting and local fees | Confirmed for your jurisdiction and project |
| Delivery and installation | Quoted for your address, access, and placement needs |
| Foundation, site work, and utilities | Quoted after reviewing the property |
Your proposal shows the home price and site work separately. Trench length, septic or sewer work, electrical upgrades, access, foundation, ramps, and delivery distance are reviewed for your property. Taxes, appliances, and work outside the agreed scope are priced separately.
People use prefab, modular, manufactured, tiny home, and stick-built as if they mean the same thing. They don’t. The differences show up in the code stamp, the crew, the calendar, and whether a lender treats the building like a house.
For a more detailed breakdown, see modular vs stick-built vs manufactured. For the lumber, snow load, and insulation comparison from Wolf’s factory video, see modular vs manufactured.
The cost table above shows Wolf’s typical pricing. It won’t be a complete estimate for every property, and it doesn’t reflect other builders’ prices.
Side-by-side
| Factory modular (Wolf) | On-site stick-built | HUD manufactured | |
|---|---|---|---|
| Where it is framed | Indoors in Battle Ground | On your lot, in the weather | In a HUD plant, on a chassis |
| Code | IRC/IBC (International Residential Code / International Building Code) residential; WA L&I or OR BCD factory insignia | IRC/IBC; local inspections on the frame | Federal HUD code |
| Foundation | Permanent (typically a 6” concrete stem-wall) | Permanent; built as the house rises | Often different placement and title rules |
| Who coordinates the work | Wolf coordinates the contracted design, permit, factory, and installation scope | GC plus subs, or a design-build shop on site | Plant plus a separate setter / retailer in many deals |
| What the city still reviews | Foundation, placement, utilities | The whole structure, plus site | Placement and local use rules; not the same as modular |
| Best fit | Repeatable ADU, cottage, or small primary home | Custom building shapes, additions, and constrained sites | Properties and uses that allow HUD-code housing |
What “prefab” covers
“Prefab” only means built off-site. Under that umbrella you will find:
- Modular: what Wolf builds. Built to the same residential code as a stick-built house, delivered in sections, and installed on a permanent foundation. The state program inspects the structure in the factory; the city or county inspects the site work.
- Manufactured / mobile: HUD code, permanent chassis. Different financing, appraisal, and sometimes zoning. Wolf homes are not manufactured homes.
- Tiny home on wheels: confirm its actual certification and the local rules for placement and occupancy. A small size or wheels alone do not establish approval as a permanent dwelling.
Labels such as “mobile ADU” do not establish the construction code or permitted use. Check the certification and the parcel’s approval path.
When stick-built makes sense
A stick-built ADU is framed on the lot. The upside is flexibility: the building can be shaped around a tree, a slope, or a custom client drawing. The tradeoff is that the site controls the schedule. Rain, subcontractor gaps, material staging, and inspection timing stretch the build, and Northwest weather causes real delays.
On-site and modular construction solve different property and design needs. RG ProBuilders describes its ADUs and MODPOD / Modern Series homes as stick-built on site in Washington and Oregon. MyADU offers stock and custom design-build services in the Portland–Vancouver metro. Wolf builds modular homes in a factory and installs them on the property. See Wolf vs RG ProBuilders and Wolf vs MyADU for more detail.
Why Wolf builds indoors
Southwest Washington is wet from fall through spring. Framing indoors keeps the module out of that weather. Shop time is typically three to four weeks once the home is in line, while permitting usually takes two to nine months. Most projects go from proposal to finished home in roughly a year.
Wolf coordinates the work included in your agreement, from the home through the contracted permit and installation scope. If a permittable dwelling is not possible, the signed permitting agreement defines the eligible refund and exclusions.
The site still matters. A modular home needs a foundation, utilities, a delivery route, and local inspections. Factory construction makes the home price more predictable, but trenching, septic work, and electrical upgrades still depend on the property. That is why the table lists site work separately.
Tiny home vs ADU vs HUD manufactured
The terms “tiny home” and “ADU” describe different things. The table below summarizes how each type is classified:
| ADU | Tiny home (Wolf sense) | HUD manufactured | |
|---|---|---|---|
| What the words mean | A legal second dwelling on a lot that already has a house | A size nickname. Model B is 307 sq ft and sits in that class | A home built to the federal HUD code on a permanent steel chassis |
| What Wolf sells | A factory modular dwelling permitted as an ADU, cottage, or small primary when the lot allows it | The same dwelling when the footprint is compact | We do not sell HUD product as an ADU |
| Foundation | Permanent (typically a 6” concrete stem-wall) | Permanent, if it is going to permit as housing | Often different placement and title rules |
| Code | IRC/IBC via the ADU / residential permit path | Same as the ADU when it is foundation-set; on wheels it may be an RV | Federal HUD code |
| Who inspects the home in Washington / Oregon | Local agency for the site; WA L&I or OR BCD for the modular structure | Same, when it is modular | HUD certification rather than an L&I / BCD modular insignia |
For a Wolf project, the first two columns usually describe the same building. HUD manufactured is a different product. See also what is an ADU.
Family occupancy, long-term rental, and short-term lodging are use questions. They do not change the code family.
How to choose
Choose stick-built when the envelope cannot be a factory module.
Choose HUD manufactured when that code and placement path fit your property and goals. It is a separate construction category from modular.
Choose Wolf modular when you want a permanent residential-code home, a controlled factory build, and Wolf coordination of the contracted permit and installation work across Washington and Oregon.
Start with the property: send us the address for an evaluation, then pick a model.
Common questions
How much does a Wolf factory-built ADU cost?
What’s the difference between an ADU, a tiny home, and a modular home?
Is a prefab ADU the same as a manufactured home?
When is stick-built the better fit?
Sources
Requirements change, so check the current forms and rules with your jurisdiction before you file. This is general information, not legal advice.