Commercial Flat Roof Spray Foam Insulation
Seamless, self-flashing insulation for commercial flat roofs — no gaps, no cold-bridging. manufacturer-certified, installed UK-wide.
Why spray foam for flat roofs
Commercial flat roofs over offices, retail units and industrial premises are notorious for poor thermal performance and persistent cold bridging. Where insulation sits between or above the deck it is often interrupted by upstands, services and parapets, and on refurbishment projects there is rarely the headroom or budget to strip back and rebuild the entire warm-roof build-up from scratch.
Enverge closed-cell spray foam is applied to the soffit or underside of the flat deck, self-bonding as it cures to form a seamless, fully adhered insulating layer with no joints or fixings to bridge. It hugs the deck profile, seals around penetrations and beam junctions, and upgrades thermal performance without disturbing the existing waterproof covering above.
This gives building owners a warmer, more efficient flat roof and a sealed underside that resists condensation on the cold deck. Energy use drops, internal comfort improves, and the upgrade is achieved from inside the building, avoiding the cost and weather risk of recovering the roof from above.
The benefits for flat roofs
Seamless Underside
Self-bonds to the flat deck soffit with no board joints or fixings to cold-bridge.
Insulate From Below
Upgrades thermal performance from inside the building, without recovering the flat roof from above.
No Cold Bridging
Continuous adhered layer eliminates the gaps and fixings that drain heat from cold flat decks.
Condensation Defence
Keeps the cold deck soffit sealed and above dew point to prevent interstitial damp forming.
Seals Penetrations
Hugs beams, services and upstands, sealing the awkward junctions rigid boards struggle to fit around.
Refurb Friendly
Ideal where limited headroom and budget rule out a full warm-roof rebuild from the top.
Continuous and seamless
Sprayed in-situ, the foam follows every upstand and penetration for a continuous insulated layer with no joints.
Applied to the flat-deck soffit, the closed-cell foam self-bonds into a fully adhered, joint-free insulating layer with no fixings to create cold bridges. Its low thermal conductivity lifts the roof U-value while low vapour permeability and the airtight seal keep the cold deck above dew point, controlling interstitial condensation from within.
- Fully adhered underside layer, no cold-bridging fixings
- Upgrades flat roofs from inside without recovering
- 25-year manufacturer-backed warranty
- Seals around beams, services and upstands seamlessly
Enverge Nexseal LE — verified performance
Typical published values for Enverge Nexseal LE closed-cell foam. Full technical specification →
Specification & compliance for flat roofs
Every roof is different, so the system is chosen to suit: Enverge Nexseal LE closed-cell foam (λ 0.027 W/m·K) where an integral vapour barrier and rigidity are needed, or Sucraseal open-cell (λ 0.039 W/m·K) where breathability matters. Condensation risk is assessed in line with BS 5250:2021 before any foam is applied — the discipline that separates a specialist commercial install from a generic one.
Applied to the underside of the deck, the foam seals every gap, junction and penetration in one continuous pass, helping the roof meet Part L upgrade targets without giving up internal space. Handover includes the full specification and a 25-year manufacturer-backed product warranty.
Where we install flat roofs spray foam
Dedicated local pages for every major city — and we cover the towns and villages between them.
From enquiry to warranty
Enquire
Tell us about your flat roofs & building.
Survey
Free survey of your flat roofs & condensation check.
Specify
The right system for your flat roofs.
Install
Approved applicators, minimal disruption.
Warranty
Handover pack & 25-year warranty.
Real flat roofs spray foam applications
Commercial projects
Richmond House Car Park
Underside of a car-park deck sealed and insulated in-situ.
The Box, Plymouth
Concrete soffit spray foam eliminating cold-bridging.
RBW Carpentry
Cavity-filling spray foam for an airtight commercial partition.
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.
Flat Roof insulation, answered
Can a flat roof be insulated from the inside?
Yes. Closed-cell foam sprayed to the underside soffit self-bonds into a continuous insulating layer, upgrading the roof from within. This avoids stripping and recovering the waterproof membrane and removes the weather risk of working from above.
Will it cause condensation on the existing deck?
No, it does the opposite. The airtight, low-permeability foam keeps the cold deck soffit sealed and above dew point, controlling the interstitial condensation that often forms on poorly insulated flat decks. We assess each build-up at survey.
Do you need to remove the existing roof covering?
Usually not. Because the foam is applied internally to the soffit, the existing waterproof covering above can typically stay in place, making this a faster, lower-disruption upgrade for occupied commercial buildings.
How does it deal with services and upstands?
The foam is sprayed continuously and self-bonds around beams, ducts, pipe penetrations and parapet upstands, sealing the awkward junctions where rigid boards inevitably leave gaps, voids and cold bridges that waste heat.
Is the system certified and warranted?
Yes, the Nexseal LE closed-cell foam we install is manufacturer-certified under Agrément 09/4610 and carries a 25-year manufacturer-backed product warranty, providing documented, independent assurance for commercial flat-roof specifications and sign-off.
Closed-cell or open-cell — which will my roof need?
It depends on the build-up: Nexseal LE closed-cell brings an integral vapour barrier and rigidity; Sucraseal open-cell offers breathability and acoustic absorption. We confirm the right system after the survey.
Is condensation risk assessed before installation?
Yes — the build-up is checked against BS 5250:2021 so the roof performs correctly through the seasons, not just on day one.
Will it help with Part L compliance?
Spray foam's continuous, airtight layer is an efficient way to reach Part L upgrade targets, and we document the installed specification for Building Control.
Insulate your flat roofs 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