Modular & Portable Building Spray Foam Insulation
Upgrade modular, portable and site buildings to a warm, condensation-free envelope — spray foam seals thin, draughty structures fast.
Why spray foam for modular buildings
Modular and portable buildings — site cabins, welfare units, classrooms, offices and relocatable blocks — are built light and thin to be moved. That thin construction means they overheat in summer, lose heat fast in winter and suffer condensation around junctions and cold steel frames, making them uncomfortable, costly to run and prone to damp.
Enverge closed-cell spray foam self-bonds to the panels, frame and substrate of a modular unit as it cures, filling awkward voids around services and frame members that conventional insulation can't reach. It seals the gaps that let draughts and moisture in, creating a continuous insulating envelope that lifts thermal performance without adding significant weight.
Insulated this way, a portable or modular building becomes a genuinely usable space: warmer in winter, cooler in summer, cheaper to heat and free of the cold-bridge condensation that blights thin-walled units. The seamless coating also stiffens and air-seals the structure, improving comfort for occupants on commercial and construction sites.
The benefits for modular buildings
Built For Site Cabins
Ideal for welfare units, offices and relocatable cabins that need to be warm, dry and cheap to run.
Air-Seals Junctions
Fills and seals draughty gaps around frames, services and panel joints that batt insulation leaves open.
Cuts Running Costs
Dramatically improves heat retention so portable units cost far less to keep warm in winter.
Tames Summer Heat
Buffers lightweight roofs and walls against solar gain, keeping cabins workable through hot spells.
Beats Cold-Bridge Damp
Stops condensation forming on cold steel frames and panel junctions inside the unit.
Lightweight Envelope
Adds a continuous insulating skin without the weight that would compromise a relocatable structure.
Seals the whole envelope
Closed-cell foam bonds to thin modular panels and seals draughts for a warm, airtight result.
Enverge closed-cell spray foam (Nexseal LE) is sprayed into the wall, roof and floor build-ups of the modular unit, self-bonding to panels and frame as it cures. It expands to fill irregular voids and seal around service penetrations, delivering both insulation and air-tightness in one continuous layer that resists moisture and reinforces the lightweight structure.
- Seals draughts around frames, panels and services
- Warmer in winter, cooler in summer cabins
- Adds insulation without heavy added weight
- 25-year manufacturer-backed warranty
Enverge Nexseal LE — verified performance
Typical published values for Enverge Nexseal LE closed-cell foam. Full technical specification →
Specification & compliance for modular buildings
Steel boxes condensate: 'container rain' ruins stored contents and corrodes the shell. A 15–25 mm closed-cell coat sprayed to the ribbed steel stops it at source — the foam bonds to every corrugation and carries its own vapour barrier. For containers and modular units being converted to occupied space, 35–50 mm+ delivers real thermal performance without stud-out framing eating the internal width.
Application and cure happen in a single day per unit, and the same approach upgrades draughty site cabins and modular buildings into warm, dry, usable space.
From enquiry to warranty
Enquire
Tell us about your modular buildings & building.
Survey
Free survey of your modular buildings & condensation check.
Specify
The right system for your modular buildings.
Install
Approved applicators, minimal disruption.
Warranty
Handover pack & 25-year warranty.
Real modular buildings spray foam applications
Commercial projects
Depot Events, Cardiff
Closed-cell spray foam across a large warehouse-style venue roof.
Ibstock Brick
Insulation for a temperature-critical manufacturing process.
The Box, Plymouth
Concrete spray foam eliminating cold-bridging and condensation.
Get a quote for your project
Send us your building details and our technical team will specify the right system and a clear budget. No obligation.
Modular insulation, answered
Can you insulate a portable building without taking it out of use for long?
In most cases yes. Spray foam is applied quickly into the relevant build-ups, and we plan works around your site programme to keep disruption to occupied welfare units, offices and cabins to a minimum.
Why is spray foam better than rolls for a modular unit?
Lightweight modular panels have awkward voids around frames and services that rolls and batts leave gappy. Spray foam expands to fill those voids and self-bonds in place, sealing draughts and cold bridges that slab insulation simply can't close.
Will it stop my site cabin being freezing in winter and boiling in summer?
That's exactly what it's for. The continuous insulating envelope sharply reduces heat loss in winter and solar heat gain in summer, making thin-walled cabins far more comfortable and much cheaper to heat and cool.
Does it help with condensation in welfare units?
Yes. By insulating and air-sealing cold steel frames and panel junctions, the foam keeps those surfaces above dew point, so the condensation and damp that commonly affect portable welfare units is greatly reduced.
Is this only for new modular buildings?
No. We retrofit existing site cabins, classrooms, offices and relocatable blocks as well as treating new units. We assess the construction on site and apply the foam into the accessible wall, roof and floor build-ups.
What depth stops container rain?
A 15–25 mm closed-cell coat is enough to stop condensation in storage containers; conversions to occupied space typically take 35–50 mm or more.
Do you need to frame the container out first?
No — the foam bonds directly to the ribbed steel with no battens or framework, preserving internal space.
How long does a container take?
Spraying and curing are typically completed within a single day per unit.
Insulate your modular buildings the right way
Specialist commercial spray foam, installed UK-wide by the Duratite Group's spray foam specialists.
Book a Free Survey →or call 01208 832 602