| Cost Line | Modular (120 units) | Conventional (120 units) | Why It Diverges |
|---|
| Unit module fabrication | $96,000–$134,000 / unit | n/a | Factory labour at $28–42/hr vs $65–95/hr site labour |
| Structure & building shell | $61,000–$84,000 / unit | $72,000–$103,000 / unit | No scaffolding, no repeated formwork, no weather protection sequence |
| MEP rough-in & fit-out | $34,000–$47,000 / unit | $42,000–$58,000 / unit | Bench assembly; approximately 22% less rework than site trades |
| Foundations & site works | $18,000–$29,000 / unit | $27,000–$41,000 / unit | Perimeter slab and pile caps only, no full-footprint slab |
| Common areas & envelope | $21,000–$31,000 / unit | $21,000–$31,000 / unit | Parity. Scope is set by the amenity programme either way |
| Construction financing period | 9–13 months | 19–26 months | Interest is charged monthly on the drawn balance |
The financing line is where the factory quietly wins. On a $28M construction loan at 8.5%, every month of programme removed avoids roughly $198,000 of interest carry. On the revenue side, 120 units stabilising at $1,850 average monthly rent produce about $2.66M of gross annual rent . So each month the certificate of occupancy moves forward is worth roughly $222,000 at the top line, before any valuation uplift on stabilised NOI. A 10-month programme compression is therefore worth more than the entire structural cost premium in most markets.
Carry Cost: The Number Developers Underweight
Carry is not just interest. It is interest, plus site security, plus construction insurance, plus the opportunity cost of equity sitting in a non-income-producing asset. On the 120-unit example above, fully loaded carry runs at approximately $310,000–$365,000 per month . Which is why a modular programme that removes 10 months of site duration does not merely save interest, it removes an entire category of monthly exposure. Our total cost planning guide breaks down all eight carry line items, and the modular apartment cost guide covers the benchmarks this table is built from.
Unit Mix Discipline: Where Modular Pricing Is Won or Lost
Modular is cheapest when modules repeat. A 120-unit building designed with four identical stacked floor plates and a single bathroom stack costs materially less per unit than the same 120 units drawn with fourteen bespoke layouts, because the factory amortises jig setup, tooling, and inspection sheets across the run. The practical rule we give developers: push variety into finishes and facade, not into structure and wet-wall positions. Repeating the wet-wall stack alone typically removes 6–9% from the modular fabrication line while changing nothing a tenant can see.
Structural Basis: What the Modules Are Actually Built From
Apartment modules in the MODURA network run on two structural platforms, chosen by storey count and seismic category rather than by price alone:
- Light gauge steel (LGS) framing . An ICC-ES ESR-5348 evaluated system, compliant with IBC/IRC 2021 plus the California and Los Angeles supplements. This is the platform to specify for seismically active US markets; our modular seismic design guide covers the ductile detailing requirements in detail.
- Q355B structural steel . Hot-rolled frames for volumetric podium builds above five storeys, supplied with full mill certificates and weld traceability, verified by SGS chemical composition analysis and covered by an SGS CPR certificate for EN 14350 light gauge steel framing.
Both platforms come out of production lines holding ISO 9001, ISO 14001 and ISO 45001 certification, with documented inspection gates at every workstation and records traceable to the module serial number. That traceability is what allows a modular apartment building to clear a lender’s third-party inspector without re-opening closed walls, the single most common cause of draw-schedule delay on conventional multi-family.
Acoustic Performance Between Units: Where Prefab Beats Site-Built
Party-wall acoustic separation is the number one tenant complaint in mid-rise rental. Our apartment modules deliver STC 55 / IIC 52 as standard, against the STC 50 / IIC 45 that most US building codes require for residential separation. The reason is structural rather than acoustic: in a factory, the flanking path between two modules can be sealed and verified before the units are closed out. On site, a subcontractor who leaves a 3mm gap behind a party wall has created a complaint the operator will live with for the whole hold period. Our acoustic performance guide covers the assembly detail and test protocol.
Ask for the documentation pack before you commit to a design, acoustic test reports, fire test certificates, steel mill certificates, and the factory inspection record template for your jurisdiction. Request the apartment documentation set and we will send it with your proposal.
Programme Comparison: 120-Unit Mid-Rise
| Milestone | Modular | Conventional |
|---|
| Design, engineering & permits | Month 0–4 | Month 0–6 |
| Foundations, site & utilities | Month 3–7 (parallel to factory) | Month 5–11 |
| Module fabrication | Month 4–11 (60–75% complete on dispatch) | n/a |
| Erection & module connections | Month 11–13 | Month 11–20 |
| Common areas, commissioning, CO | Month 13–16 | Month 20–28 |
| First rent roll | Month 16–18 | Month 27–31 |
The overlap between site works and factory production is the whole mechanism. Module production runs independently of weather and of site readiness. A delayed foundation does not stop the line, it only delays erection, and completed modules queue in the yard rather than accumulating standing time in the open. That is why the schedule variance on a modular apartment programme is measured in weeks, not quarters.
Questions We Are Asked Before Every Apartment Contract
- Can you meet our lender’s inspector? Yes, modules carry serialised factory inspection records, and we supply the assembly documentation pack (acoustic, fire, steel mill certificates) before the first draw request. Our payment draw schedule guide explains how modular draws are structured.
- How tall can you go? 3–12 storeys on steel-frame volumetric modules, with a concrete podium for five storeys and above. Above twelve storeys we move to a hybrid core-and-module approach, our hybrid construction guide covers the trade-offs.
- What if our site is tight? Prefabrication removes the laydown and staging footprint that constrains conventional mid-rise on urban infill. See our brownfield and constrained urban site guide for the crane and delivery planning method.
- What warranty comes with it? 10-year structural, 2-year finish, 1-year systems, documented in the O&M manual at handover, not as a verbal promise.
- Who is liable if a module is defective? The factory carries the defect, and it is fixed at the factory’s cost before dispatch. That is a materially different risk position from discovering a site-built defect behind closed drywall. Our insurance and risk management guide covers the liability transfer in detail.
