Guide
Modular vs Stick-Built Construction: Factory to Set Day
Factory phases, site work that still happens on the lot, set day, and where stick-built sequencing still applies.
Modular vs stick-built: start with the schedule, not the brochure
A stick-built house is a single critical path on one lot: permits, foundation, framing, enclosure, trades, finishes, then occupancy. Weather, trade stacking, and change orders live on that same path. A modular house splits the path. The plant builds, inspects, and weathers in the modules while the site crew clears, grades, and pours. The two streams join on set day.
That split is the entire product. If you treat a modular job like a shortened stick-built job, you will under-specify the foundation, ignore crane access, and let the factory sit waiting on permits. The rest of this guide is the modular sequence, with stick-built notes only where they still apply on site. For a week-by-week factory walkthrough, use the modular home building process guide.
1. Pre-construction for a modular project
Plan, code, and transport envelope
Modular design is not just floor-plan shopping. Modules must fit highway limits, crane capacity, and the plant's jig. Ceiling height, roof pitch, and stair placement are constrained by shipping. The engineer stamps the modules to the International Residential Code (or the state's adopted code) plus transport loads. That extra lumber is not a marketing flourish. It is how the box survives the truck.
Budget beyond factory price
Base unit costs often land around US$50-US$100 per sq ft for delivered modules (a 1,500 sq-ft home about US$75k-US$150k at that factory line). You still budget land, site work, permanent foundation, delivery and crane, utilities, permits, taxes, and upgrades. Site complexity, not the catalog price, is what blows modular budgets.
Zoning, access, and contractor selection
Confirm in writing that IRC modular (not HUD manufactured) is allowed on the lot. Check turning radius, overhead lines, and soil. Solicit bids that split factory, set crew, and site work. Contracts should define who owns permits, marriage-wall finishing, and punch-list warranty. Homeowners who skip this step usually discover it on set day.
2. Site preparation (this still happens on the lot)
Start with zoning and setbacks, then survey, clearing, excavation, and grading. For modular projects, site prep commonly runs US$4,000-US$11,000 all-in: survey about US$350-US$1,000, clearing US$1,350-US$3,900, excavation US$1,600-US$4,400, grading US$600-US$2,000. Walk the lot after rain. Ponding tells you where the foundation and drainage will cost more.
Permitting plus site prep typically takes 1-2 months, longer if the municipality is backlogged or the septic design is new. This is the phase that should overlap factory production. If permits lag, the plant will store modules and charge for it.
3. Permanent foundation (required for IRC modular)
Modular homes are not parked. They are set on a permanent foundation sized to the module layout, point loads, and local frost depth. Approximate costs: pier-and-beam US$3k-US$8k, crawl space US$6.3k-US$16.3k, basement US$20k-US$29k, pilings for flood sites US$12k-US$30k. Crawl spaces and basements are common because utilities and marriage-line connections need access under the modules.
After the foundation cures, a local inspector checks dimensions, embeds, and any under-slab plumbing. Stick-built jobs inspect footings the same way. The modular difference is tolerance: a foundation that is out of square by an inch can stall a crane set. Have the set crew or manufacturer review as-built dimensions before trucks roll.
4. Factory construction (where framing actually happens)
Stick-built framing, roofing, window install, insulation, and most MEP rough-in happen on your lot. Modular plants do that work on a line. Third-party inspectors stamp stations before the module ships. You should receive in-plant inspection reports and, at delivery, a state insignia on each module, not a HUD red tag.
Factory construction typically runs 1-2 months. Design lock is earlier than stick-built because the jig does not like late electrical moves. Change orders after production starts are expensive. If you want to understand plant vs HUD manufacturers, see best modular home builders 2026.
Rough plumbing, wiring, and HVAC that a stick-built crew would install after dry-in are already in the boxes. That is why published stick-built line items (rough plumbing US$8,000-US$12,000, wiring a 1,000 sq-ft home US$3,269-US$6,084, HVAC US$7,000-US$16,000) are not a 1:1 modular budget. Those costs are mostly inside the factory invoice, with site tie-ins billed separately.
5. Delivery, crane set, and button-up
Delivery and installation often take 1-2 weeks of intense work, not months of framing. Trucks, escorts, and a crane have to fit the site. Narrow roads and overhead lines are the usual extra fees. Modules are set, roofs and marriage walls are weatherproofed, and utilities are tied through the foundation.
Typical modular timeline when the two paths overlap:
- Design and planning: 1-3 months (plan, engineering, financing).
- Permitting and site prep: 1-2 months (review, survey, clearing, grading).
- Factory construction: 1-2 months (climate-controlled plant).
- Foundation: about 1 month (should overlap the factory build; basements add time).
- Delivery and installation: 1-2 weeks (crane set, button-up, hookups, inspections).
- Finishing and move-in: a few weeks (remaining flooring, paint, exterior, certificate of occupancy).
HUD manufactured homes often finish in 4-6 months with a different code path. Stick-built homes often run 9 months or more because framing cannot start until the foundation is done and cannot finish until the weather cooperates.
6. On-site finishes (the leftover stick-built work)
Some drywall seams, flooring, exterior cladding, driveways, and landscaping still happen after set. Exterior finishes (brick, stone, siding, stucco) may be plant-applied or site-applied depending on the plan. Exterior grading typically costs US$1,400-US$3,700. Garages, decks, and premium finishes are owner upgrades: garages and decks might run US$5k-US$50k; premium finishes US$10-US$150 per sq ft.
Final inspections, punch list, warranties, and manuals look like any other house. Occupancy still needs the local building official, not only the plant inspector.
Modular vs stick-built construction
Stick-built homes are constructed on-site in phases (foundation, framing, trades, finishes) to the IRC and local codes. Modular homes are built as sections in a factory, assembled on a permanent foundation, and also follow the IRC. Manufactured homes are a third path: HUD Code, steel chassis, different financing. Do not mix those three in a bid comparison.
Customization: stick-built is open-ended; modular is plan-plus-options with transport limits; HUD is mostly catalog. Cost bands commonly cited: stick-built US$150-US$300+ per sq ft, HUD manufactured US$80-US$160 fully installed, modular US$90-US$120 assembled before site extras. Timelines: stick-built about 9 months or longer, modular about 3-6 months, HUD about 4-6 months. Modular and stick-built generally appreciate with the local housing market when they are real property. HUD personal-property units often do not.
Common modular pain points and solutions
| Pain point | Why it happens | Solution |
|---|---|---|
| Unexpected costs | Buyers price the factory invoice and skip site work, crane, and upgrades. | Build a total-cost worksheet: land prep, foundation, transport, utilities, permits, 10-20% contingency. |
| Permitting delays | Plans omit local engineering or the department has never seen modular stamps. | Submit complete sets early, assign a local PE if asked, and do not let the plant ship into a permit vacuum. |
| Factory vs site gap | Nobody owns marriage walls, HVAC tie-in, or punch list. | One contract matrix: manufacturer, set crew, GC. Name the owner of each finish item. |
| Schedule slip | Site access, weather on foundation, or late utilities. Stick-built framing risk is mostly gone; site risk is not. | Buffer the foundation and utility dates. Order the crane only after as-built foundation checks. |
| Financing friction | Lender treats the job like HUD chattel or will not inspect factory draws. | Use a modular-experienced lender. Draws follow factory, foundation, set, and occupancy. See classification and resale. |
| Site access | Narrow roads, steep drives, or soft soil block trucks and crane pads. | Walk the route with the transporter before you order. Budget temporary road mats if needed. |
Frequently asked questions
How does the modular construction process differ from stick-built?
Stick-built framing, MEP rough-in, and most finishes happen on the lot, in sequence, exposed to weather. Modular homes complete most of that work in a factory while the site crew builds the foundation. On-site work is set, marriage walls, utilities, and remaining finishes.
Can site work happen while the factory builds the modules?
Yes. Permitting, grading, and foundation work should run in parallel with factory production. That overlap is why modular schedules are often 3 to 6 months instead of 9 months or more.
What happens on set day?
Modules arrive on trucks, a crane sets them on the certified foundation, crews weatherproof the roof and marriage walls, and inspectors check connections. Button-up and utility hookups follow over days to a few weeks.
Do modular homes still need a permanent foundation and local inspections?
Yes. IRC modular homes sit on a permanent foundation and take local inspections in addition to in-plant third-party inspections. Factory stamps do not replace the building department.
Where does stick-built work still show up on a modular job?
Foundation, site utilities, driveways, some exterior finishes, and punch-list items remain on-site. If your lot has poor access or a complex basement, those site phases can dominate the calendar even when the factory is fast.