How long to build a modular home

Marketing pages say a modular home takes two to four months. That number is usually factory production after the slot opens. Forum buyers describe delivery in late fall and still waiting on button-up, utilities, and a certificate of occupancy months later. A realistic U.S. project is 6 to 12 months from land feasibility to keys. Complex permits or custom plants can run 12 to 18.

This page is the critical path. Step-by-step ownership and inspections live in the building process guide. Phase language that includes stick-built comparison lives in Construction process.

Critical path (typical ranges)

The compression vs stick-built happens because weather does not stop the plant. It does not happen if you start the factory before the foundation is legal.

Why sites advertise 2 to 4 months

They count shop time. They skip the permit queue, the perc retest, the crane week that slipped because the driveway was mud, and the plumbing inspection that failed because a sub did not show. PERCH's 2026 seven-step reference puts total time at 6 to 18 months and warns that treating the job as one transaction is the usual failure mode. Agree with that.

Set day is not move-in day

After the crane leaves you still have roof and siding seams, interior tape and paint at the marriage line, mechanical connections, well or municipal hookups, and a punch list. Tile and some finishes should wait until the box is set. Buyers on r/Homebuilding report that a GC who subs everything can lose weeks when one trade is late. Name the finish contractor in the contract and put liquidated damages or at least a written sequence in the exhibit.

Financing clock versus factory clock

If the lender cannot fund a factory draw, the plant will not load the truck. Lock the construction-to-perm product before you take a build slot. A retail pre-approval does not move money. See the lender confusion packet.

Seasonal traps

Northern and mountain sites lose set weeks to frost, snow load access, and spring thaw. Gulf and Atlantic sites lose weeks to hurricane closures and wet soils. Book the crane after the foundation inspection has passed, not on a marketing "delivery month."

A 9-month example

Month 1: zoning letter, perc, survey. Month 2: construction lender and factory selections. Months 3 to 4: permits and foundation. Months 4 to 6: factory build in parallel with site. Month 7: set. Months 7 to 9: button-up, utilities, CO. That calendar matches owner reports in our catalog reviews more often than a 10-week brochure.

Use the cost calculator so the extra months have a cash-flow plan, and buyer help if you want someone to pressure-test a builder's promised date.

Road and crane permits

Module trucks need a route survey: low wires, weak bridges, tight turns, seasonal weight limits. The factory or the hauler should produce that survey before you lock a set week. You still own tree trimming and a temporary driveway wide enough for the truck and outriggers. Typical planning numbers: 16 to 20 feet of clear width and a pad that can take the crane without sinking.

Power lines across the only street frontage are a classic Reddit kill shot for ADUs and small lots. A second crane day or a panelized switch can erase the factory savings.

Inspection sequence that holds the CO

Foundation inspection before set. Set and marriage-line inspection. Mechanical, electrical, plumbing rough-ins after connections. Insulation and drywall at the seams. Final and CO. Miss one and the lender will not convert the construction loan. Put the inspection list in the same exhibit as the draw schedule so nobody claims they were waiting on "the other guy."

When a rush job is still slow

Paying for a faster factory slot does not move the planning commission. It does not make clay soils drain. The only honest rush is: land already permitted, foundation already poured, lender already in construction mode. Anything else is a marketing date.

Storage fees and site-not-ready

If the truck arrives and the foundation failed inspection, you pay to store the modules. Plants quote daily or weekly storage plus an extra haul. Buyers on r/Homebuilding treat this as the most avoidable cash leak. The prevention is boring: foundation sign-off in hand, access road dry enough for the crane, utilities located, and the set crew booked for the same window as the truck. Put a site-ready definition in the contract so almost-ready is not your problem.

Hold a 30-minute call the week before set with factory, hauler, crane, GC, and you. If any one of them cannot confirm, delay the truck. A delayed truck is cheaper than a stored house.

Certificate of occupancy is the only date that matters for insurance, tax, and the permanent mortgage. Temporary power and a lockbox do not count. If a builder says you can move in while waiting on CO, ask the building official in writing. Many jurisdictions treat that as occupancy without a permit.