Modular Building Design Guides & Technical Resources

Downloads

Design Resources

Free technical resources to help you design, specify, and deliver modular buildings. All content is authored by our engineering team and updated quarterly to reflect the latest standards and product developments.

MODURA BIM Families

Revit families (.rfa), IFC models, and ArchiCAD objects for all MODURA standard module types. LOD 350 with parameter-driven dimensions, UK and European content libraries. Updated quarterly to reflect product changes. Free download, no registration required for basic families. Full library access with email registration.

FREE Download

Technical Specification Library

NBS Chorus specification clauses ready for insertion into your project specification. Certification references match the destination market.

FREE Download

Drawing Templates

General arrangement plans, module layout sheets, MEP coordination drawings, foundation interface details, and connection detail library. Available in DWG and PDF formats with standard MODURA title blocks. Includes a sample project drawing set (50-unit residential) showing the complete documentation package for a real completed project.

DWG + PDF

Sample Specifications

Five worked example specification sets, each covering a complete building type: multi-family residential (Spec A), hotel (Spec B), office (Spec C), healthcare (Spec D), and education (Spec E). Each includes structural loading assumptions, fire strategy, acoustic targets, MEP specification, and finishes schedule, ready to adapt for your project.

5 Spec Sets

Design Rules

Design for Manufacture (DFM) Rules

These ten DFM rules capture 15 years of modular manufacturing experience. Following them from the start of design avoids costly redesign later. Modules that comply with these rules flow through the factory with predictable quality, cost, and programme.

Rule	Requirement	Reason
Module width	Standard: 3.6m, 4.0m, 4.2m. Maximum: 4.5m	Road transport limit. Wider modules require escort vehicles and route-specific permits, increasing cost and lead time.
Module length	Standard: 9m, 12m, 14m. Maximum: 16m	Transport and cranage constraints. Longer modules reduce module count but increase weight, requiring larger cranes.
Module height (internal)	Minimum 2.4m finished floor to ceiling. Standard 2.55m	Building regulations minimum plus allowance for MEP services distribution within the ceiling void.
Structural grid	Align module joints with the structural grid. Avoid columns inside module footprints	The module joint IS the structural grid line. A column inside a module forces a split-module design, doubling complexity.
Service risers	Locate in dedicated riser modules or at module junctions. Vertical continuity is essential	Pre-fabricated risers are assembled and pressure-tested in the factory before dispatch. Site connections plug-and-play.
Wet areas	Locate bathrooms and kitchens at module perimeter for drainage falls. Avoid central wet areas	Drainage must gravity-feed to the riser. Central wet areas require pumped drainage, adding cost and maintenance liability.
Party walls	Double-skin construction with 50mm cavity minimum. No direct structure-borne path between modules	Acoustic isolation target: D_nT,w + C_tr ≥ 45dB. Achieved through complete structural separation between adjacent modules.
Ceiling services	Allow 150mm minimum ceiling void for MEP distribution. 200mm preferred where ventilation ducts are routed	MEP first fix is pre-installed in the factory ceiling void. Inadequate void depth forces on-site rework and compromises quality.
Floor build-up	25mm raised access floor or screed above the structural floor cassette	Provides the service distribution zone plus acoustic isolation from the floor above. Pre-installed in the factory.
Facade attachment	Design facade as an independent rain screen with thermal break at module edge	Accommodates differential movement between modules. Maintains thermal continuity and weatherproofing across module joints.

Parameters

Recommended Technical Parameters

Industry-proven technical parameters for five common building types. Use these as starting points for your project brief. All parameters are based on UK and European regulatory requirements and can be adjusted for local codes.

Parameter	Residential	Hotel	Office	Healthcare	Education
Floor-to-floor height	2.9–3.0m	3.0–3.3m	3.3–3.6m	3.6–4.2m	3.0–3.3m
Structural steel grade	S275–S355	S275–S355	S355–S460	S355	S275–S355
Fire resistance	60 min	60–90 min	90 min	120 min	60–90 min
Acoustic D_nT,w+C_tr	≥45dB	≥50dB	≥45dB	≥50dB	≥45dB
Thermal U-value (wall)	0.18 W/m²K	0.18 W/m²K	0.18 W/m²K	0.15 W/m²K	0.18 W/m²K
Design life	60 year	60 year	60 year	60 year	60 year
Ventilation strategy	MVHR / MEV	MVHR + AC	MVHR + AC/VRF	HEPA MERV 15	MVHR

Lessons Learned

Common Design Mistakes to Avoid

After completed projects and 10,000+ modules, we have seen the same mistakes repeated. These six are the most frequent and the most expensive to fix. Design around them from day one and your project will run smoothly.

Exceeding Transport Limits

Designing modules that exceed transport limits. Check maximum dimensions (4.5mW × 16mL × 3.6mH for road) before finalizing your layout. Wider modules need escort vehicles which increase cost. Longer modules need heavier cranes which increase cost. Design within standard envelope dimensions unless the programme benefit demonstrably outweighs the logistics premium.

Structural Elements Inside Module Footprint

Placing columns or shear walls inside module footprints. Columns and shear walls should ALWAYS align with module edges. A column inside a module forces a split-module design, doubling the module count and joint complexity. The module joint IS the structural grid, align all vertical structure with it from the earliest concept stage.

Assuming Site Tolerances Match Factory

Assuming site tolerances match factory tolerances. Module-to-module: ±2mm. Foundation: ±5mm. Allow a 20mm tolerance zone at the module-to-foundation interface. Do NOT design zero-tolerance connections between factory-produced modules and site-poured foundations. Every interface between factory work and site work needs an adjustable connection detail with defined tolerance accommodation.

Forgetting About Cranage

Check four things before locking the site layout: Is there crane access on all four sides of the building? Can the crane reach the furthest module at the required working radius? Is the ground bearing capacity adequate for the fully-loaded mobile crane? A mobile crane needs a minimum 15m × 15m hardstanding area. If the answer to any of these is no, the logistics plan needs to change.

Over-Specifying Unique Module Types

Each unique module type requires a separate jig setup on the factory production line. Target ≤8 unique module types per project. Use repeat module types with different internal fit-outs. Kitchens, bathrooms, and finishes can vary without changing the structural module chassis. Every unique structural module type above 8 adds approximately one week to the production programme.

Late Changes After Production Starts

Changing room layouts after Station 9 (finishes) costs 5–10× the original change. ALL design decisions should be locked no later than Station 3 (steel frame). Request a factory sample module if you are unsure about finishes or layouts. Seeing a full-scale physical module is far cheaper than changing 100 modules after they are built.

Compatibility

File Formats We Accept

We work with industry-standard file formats across all design and engineering disciplines. If your team uses a format not listed here, contact our BIM team. We can accommodate most software ecosystems through IFC interoperability.

Architectural: Revit (.rvt), IFC 2×3 / IFC 4, DWG, SketchUp (.skp)
Structural: Revit, Tekla Structures, IFC, DWG
MEP: Revit with Systems, IFC, DWG
Point Clouds: .e57, .rcp, .pts (for existing building retrofit and refurbishment projects)
Specifications: NBS Chorus, Microsoft Word, PDF
Programme: Microsoft Project, Asta Powerproject, Primavera P6
BIM Data: COBie, IFC with property sets aligned to ISO 19650

All files are handled under NDA. We maintain ISO 19650-compliant Common Data Environment (CDE) for every project. Your data is secure, version-controlled, and accessible to authorized team members only.

MODURA BIM coordination workspace showing Revit model with structural, architectural, and MEP disciplines overlaid

Module Library

The Standard Module Set. What Fits on a Truck, and What It Costs to Move

Every design decision starts with transport. If a module cannot move on a standard flatbed without permits, escort vehicles, or police notification, the saving it creates in the factory is consumed by logistics. This is the module set we build most often.

Module Type	External Dimensions	Floor Area	Transport Class	Typical Use
Guest / bedroom module	3.6 m × 8.4 m × 3.0 m	30.2 m²	Standard flatbed, no permit	Hotel rooms, apartments, student beds, staff accommodation. The single most-manufactured unit in the network.
Narrow module	2.9 m × 8.4 m × 3.0 m	24.4 m²	Standard flatbed, no permit	Corridors, bathrooms and ablution blocks, plant rooms, and narrow-site infill where the site access road is tight.
Double module	6.0 m × 9.0 m × 3.0 m	54.0 m²	Wide load, escort often required	Open-plan offices, dining and communal areas, clinic treatment rooms, retail units. Joins two structure lines on site.
Long module	3.6 m × 12.2 m × 3.0 m	43.9 m²	Length permit and route survey required	Corridor spine with integrated risers, and combined bedroom-plus-bathroom units where fewer joints on site is worth the haulage complexity.
Link / stair core	Custom, typically 3.0–4.5 m wide	Varies	Case by case	Circulation, stairs, and vertical MEP distribution. Designed last, after the room modules are fixed, because it absorbs the dimensional tolerance of the whole assembly.

The transport class column is the one to read first. A standard flatbed move in most jurisdictions means a load up to roughly 2.55 m wide and 13.6 m long travelling without a permit. The guest module at 3.6 m × 8.4 m sits comfortably inside that envelope and travels as a normal load, no escort, no route survey, no night-time curfew. The moment a module exceeds about 3.0 m in width or 13.6 m in length, the programme gains a permitting lead time per delivery and, in many jurisdictions, restricted travel windows.

The practical consequence: design the room and then let the module follow. A 30 m² guest module delivers a hotel room, an apartment bedroom with ensuite, or a student bed space. Push a layout to 35 m² and you have crossed into a wide load, which costs more to move than the extra 5 m² is worth in any of those programmes. The full envelope constraints are set out in our shipping and transport guide.

There is one legitimate reason to accept a wide or long load: reducing the number of joints on site. A corridor spine module at 12.2 m replaces two 6 m modules and eliminates one structural joint, one MEP connection, and one weather-seal interface. On a programme with hundreds of bed spaces, that trade can be worth the permit. On a single small building, it almost never is.

Cost of Late Changes

What a Design Change Costs, by Stage

The most expensive mistake in modular construction is not a wrong dimension. It is a right decision made at the wrong time. The same change costs orders of magnitude more depending on when it lands.

Stage	What Changes Are Possible	Relative Cost	Typical Turnaround
Concept and briefing	Almost anything: module count, mix, planning strategy, structural system, facade language	1× (baseline)	Days, it is drawing time
Design development	Room layouts, facade articulation, MEP route changes, module boundaries	2–4×	1–2 weeks, requires re-coordination across disciplines
Design freeze / pre-production	Fixture selections, finish schedules, minor booking changes. Still open, but the structural and MEP logic is locked	5–10×	1–3 weeks; drawings must be reissued and re-approved
Steel cut and frame on jig	Non-structural items only: finishes, fittings, equipment specification	20–50×	3–6 weeks if it touches structure or MEP; scrap value on fabricated steel is near zero
MEP first fix installed	Almost nothing without opening the module. Sanitary, drainage falls, and cable routes are set	50–120×	6–10 weeks; the module leaves the line and a slot opens in the production sequence
Module closed and finished	Nothing economical. A change means demolition inside a finished unit	100–250×	Weeks, and the production slot for the replacement module competes with your own later modules
Module on site / erected	Site modification only, often with a crane and a re-seal	200–500×	Weeks, plus it blocks the trades working behind the module in the erection sequence

These multipliers look dramatic, and they are, but the mechanism is mundane. In a modular factory, hundreds of units move through a fixed sequence of stations. A change that requires a module to leave the line does not cost one module's worth of rework; it costs the slot that module occupied, because every unit behind it keeps moving. That is why the cost curve is not linear and why "we will sort it out in the factory" is the single most expensive sentence in a modular project.

The practical discipline is a formal design freeze. Treat it as a hold point with a named signatory and a defined scope of what remains open after it, finishes and fittings, but never module dimensions, structural steel, or MEP routing. If a client cannot commit at that point, the correct decision is to delay production, not to start it and hope. Delaying production costs programme; changing after production costs programme and money and erodes the factory's ability to recover the lost slot.

The three decisions that must be final at freeze, because they are the most expensive to reverse, are module dimensions and mix, wet area positions and drainage falls, and structural openings. Everything else has a recovery path. Our project process explains where the design gate sits and what documentation must be signed at it.

Documentation

What a Specifier Needs From Us, and What Certifies It

Design guides are only useful if the design can actually be approved. These are the named certification documents behind the structural and envelope system, mapped to the design decisions they unlock.

Design Decision	Document That Unlocks It	Issued By
Specifying a light gauge steel frame and expecting the authority to accept it	ICC-ES ESR-5348 . Evaluation of the LGS framing system against the IBC and IRC 2021 editions, including the California and Los Angeles supplements	ICC Evaluation Service
Claiming a compartment fire rating on the structural panel assembly	Intertek WH Fire Test Report . Loadbearing steel stud panel assembly tested to ISO 3008-1	Intertek
Securing CE marking for a European or UK procurement route	SGS CPR Certificate . Light gauge steel framing to EN 14350 under the Construction Products Regulation	SGS
Substantiating a stated yield strength on the structural drawings	SGS Steel Test Report . Chemical composition and mechanical properties of the Q355B structural steel used in frames and connection plates	SGS
Accepting the materials at a factory audit or for a material-substitution approval	CQC Green Building Materials and CQC Steel Products product certification	China Quality Certification Centre
Qualifying the factory itself in a supplier pre-qualification process	ISO 9001:2015 / ISO 14001 / ISO 45001 management-system certificates for quality, environment, and occupational health and safety	Accredited certification bodies

Two parameters in the table on this page are worth restating with their basis, because specifiers ask where they come from. The STC 55 / IIC 52 rating delivered by the standard party-wall assembly is a tested figure, not a target, and the assembly that produces it is set out in our guide to acoustic performance and soundproofing in modular buildings. The one-hour fire rating rests on the Intertek panel test above rather than on a nominal assumption.

Where a project needs code acceptance rather than a supplier claim, the useful precedent is a real approval in a demanding jurisdiction. A publicly procured interim housing community in Soledad, California was delivered in 2026, and the structural system has been through the ICC-ES evaluation route that a US authority having jurisdiction expects to see. Production runs across six container production bases with a permanent modular line added in 2025, serving more than 60 countries, relevant when a specification calls for repeat delivery against a fixed module set rather than a one-off build.

For comparison work, the design parameters above are the ones to bring to a modular versus traditional construction evaluation, and the transport envelope table is what to bring to a modular versus container construction comparison. The two differ most in exactly that dimension, because a shipping container is fixed at 2.44 m internal width.

Pre-Contract Questions

Questions Design Teams Ask Us Before Every Project

These five come up in almost every design coordination meeting, usually in the first hour after the architect has seen the transport envelope table.

Can we design the building first and then break it into modules?
Not without paying for it. The order that works is the opposite: fix the module set from the transport envelope, then lay out the building inside it. Attempting a free-form design and slicing it afterwards produces modules that exceed transport limits, wet areas that do not align with structural walls, and corridor widths that change at every joint. If the design must start from an architectural concept, the module grid has to be imposed at concept stage, not at the end of design development. The how it works page shows where that imposition happens in our sequence.

How much dimensional tolerance should we allow between modules?
Assume 5–10 mm of cumulative tolerance per module in each direction, and design the facade, corridor lining, and floor finishes to absorb it rather than attempting to eliminate it. This is why the lower-value modules gets the tight joints and the link or stair core is designed last: the core absorbs the accumulated tolerance of the whole assembly. Specifications that demand zero-tolerance joints on site usually fail at the first weather seal.

Where should wet areas go?
Centralised and stacked, with gravity drainage running to a common riser. Drainage must fall to the riser. A bathroom placed at the far end of a module needs a pumped drainage system, which adds both cost and a maintenance liability for the life of the building. Scattering wet areas to suit an apartment plan is one of the six mistakes on this page, and it is the one that most often gets discovered after the modules are on the jig. Acoustic and MEP consequences of wet-area placement sit beside the isolation targets in our MEP systems integration guide.

Do your standard modules lock us into a standard building?
No. The module is a dimensional and structural unit, not an architectural one. Facade language, balcony strategy, roof articulation, and internal layout are all project-specific. What the standard set fixes is the transport envelope and the join logic, which is the part that carries the cost. Within a 3.6 m × 8.4 m × 3.0 m unit there is a wide range of room types, and the design flexibility case is set out in full in our guide to modular building design and customisation.

What if the site cannot take a crane?
It is a design constraint that must be identified in the first week, not the last. Cranage reaches over the building, so a tight urban site can usually still be served from a single standing position. But the module size and the erection sequence both depend on where that position is, and it may rule out long modules entirely. Sites with no crane access at all need a different structural approach and are evaluated case by case; the same question applied to remote locations is covered in our remote workforce housing guide.

Engineering documentation pack on request. The naming and numbering conventions for your BIM families, the technical specification library, drawing templates, and the full certificate set, ICC-ES ESR-5348, the Intertek ISO 3008-1 fire test report, the SGS CPR EN 14350 certificate, the Q355B steel report, and the ISO management-system certificates, are available to design teams and tender submissions. Request the documentation pack →

Design Guides & Technical Resources