Home›Piling & Below Ground Insulation
Spray foam insulation for sheet piling, retaining walls and basement structures. Nexseal LE delivers exceptional thermal performance at 0.027 W/m·K with an integral vapour barrier — critical for any structure below ground level — bonding directly to steel sheet piling, concrete and blockwork without fixings, battening or framing.
Nexseal LE is the ideal product for below-ground applications. This closed-cell spray foam delivers exceptional thermal performance at 0.027 W/m·K while providing an integral vapour barrier — critical for any structure below ground level. The closed-cell structure provides complete moisture resistance, bonding directly to steel sheet piling, concrete retaining walls and blockwork.
Below-ground retaining walls: concrete and masonry walls below ground present unique challenges — ground moisture pressure is constant, surfaces are often irregular, and services penetrate the walls in multiple locations. Nexseal LE provides the critical vapour barrier that prevents moisture migration from the ground into habitable spaces, while delivering a thermal break that prevents cold bridging through concrete walls — seamlessly, around every service and penetration, with no separate membrane or VCL required.
Steel sheet piles create a deeply profiled surface that is impossible to insulate with rigid boards — the corrugated geometry leaves gaps, cold bridges and uninsulated steel sections. Nexseal LE conforms perfectly, expanding to fill every trough, flange and interlock.
Fills every trough, flange and interlock of the corrugated sheet piling seamlessly — a continuous insulation envelope across the entire piling surface.
No gaps behind corrugations, no uninsulated steel sections — the thermal bypass paths that defeat board-based systems are gone.
Applied to both piling and infill panels simultaneously — one continuous layer across every junction.
Bonds directly to steel — no fixings that penetrate the structure or create corrosion points.
Below-ground structures demand insulation that can resist moisture, bond to complex substrates and provide a continuous barrier with no joints or gaps. Nexseal LE delivers on every count.
Closely-spaced bored concrete piles with concrete or blockwork infill. Foam bonds seamlessly across piles and infill panels, eliminating cold bridges at every junction. The most common piling type on UK commercial basements.
Interlocking concrete piles form an uneven surface rigid boards cannot follow. Nexseal LE conforms to the curved pile faces and fills every interlock.
Deeply corrugated steel retaining walls. Foam expands into every corrugation, filling troughs and wrapping flanges to create a seamless thermal envelope.
Cast in-situ concrete walls formed in deep trenches. The flat surface accepts foam at consistent thickness — insulation plus vapour barrier against ground moisture pressure.
Cast concrete, blockwork and masonry basement walls. The integral vapour barrier handles constant hydrostatic moisture pressure — no separate tanking membranes or VCLs.
Whatever your below-ground structure, Duratite provides specification support and installation UK-wide — call 01208 832 602 for a free site survey.
| Feature | Nexseal LE Spray Foam | PIR / Rigid Board | Shotcrete | Tanking Membrane + Board |
|---|---|---|---|---|
| Thermal Performance | 0.027 W/m·K | 0.022 W/m·K | ~1.0 W/m·K (very poor) | 0.022 W/m·K + losses at joints |
| Vapour Barrier | Integral (built-in) | Separate VCL required | None — porous material | Tanking membrane required |
| Cold Bridges | Eliminated (seamless) | Risk at joints & fixings | Minimal insulation value | Risk at joints & fixings |
| Irregular Surfaces | Conforms to any profile | Cannot follow corrugations | Conforms but adds significant weight | Cannot follow corrugations |
| Weight Added | Minimal (30–35 kg/m³) | Light | Heavy (2,300 kg/m³) | Moderate |
| Mechanical Fixings | None required | Adhesive + fixings needed | Steel mesh reinforcement | Fixings penetrate membrane |
| Installation Speed | Same day | 2–3 days | 2–4 days + curing | 3–5 days (multi-trade) |
| Moisture Resistance | Closed-cell — resists ingress | Absorbs moisture over time | Porous — absorbs moisture | Depends on membrane integrity |
| Third-party test basis | BS EN 14315-1 declared values | Varies by product | Not typically tested | Varies by product |
Delivered by our approved installer network across the UK.
Appointed by Cook Group Limited to design and deliver a technically advanced insulation solution to the steel sheet piling infill sections of the Durham Light Infantry Museum Extension — Nexseal LE plus Bostik Idenden ET150 protective coat to 29 rebates, with full install, cure and coating delivered in three days.
Below-ground retaining wall sprayed with Enverge Nexseal LE closed-cell foam — a faster, lighter shotcrete alternative. Closed-cell foam applied up to 400mm, 78 kPa compressive strength, tack-free in 60 seconds.
Nexseal LE bonded to AZ 18-700 steel sheet piles forming a below-ground retaining structure — engineered to U = 0.18 W/m²·K, eliminating shotcrete and shuttering, finished with an ET150 grey vapour-barrier topcoat. Read the full case study →
Free site survey, engineered design, professional installation, full documentation.
We assess the piling or retaining wall structure, measure areas, review ground conditions and identify access requirements. Free and no-obligation.
We specify thickness, confirm substrate compatibility, perform U-value calculations and produce a fixed-price quotation tailored to your below-ground application.
Manufacturer-trained technicians spray-apply Nexseal LE directly to the piling or retaining wall. The foam bonds seamlessly to steel and concrete substrates.
You receive thickness verification logs, site photographs, warranty documentation and U-value compliance paperwork for your project records.
The UK’s trusted spray foam insulation specialists — delivering piling and retaining wall insulation systems for construction projects nationwide.
Over a decade delivering professional spray foam insulation projects for piling, retaining walls and below-ground structures across the UK.
Commercial projects across the UK including sheet piling, retaining walls, basements, warehouses and commercial structures.
Our approved installer network is directly trained and certified by Enverge to ensure every installation meets manufacturer specifications.
From initial survey through to completion and handover — we manage every aspect and coordinate with main contractors on construction projects.
Enverge Nexseal LE performance below ground is evidenced by the manufacturer’s declared values tested to BS EN 14315-1. Our group company ThermoHoldings Ltd holds BBA Agrément Certificates 23/6963 and 23/6845, but their scope is domestic buildings — pitched roofs, external walls and suspended timber floors — so they do not cover this work.
Complete risk assessments, method statements and project documentation provided for every project. Accepted by main contractors and CDM coordinators.
We needed a specialist insulation solution for the sheet piling on a complex below-ground structure. Duratite delivered exactly what was needed — the Nexseal LE conformed perfectly to the corrugated profile and provided the vapour barrier we required. Professional team throughout.
Structural project engineerThe retaining wall insulation was completed on programme and to a high standard. Duratite coordinated with our main contractor without any issues. The spray foam system was far more practical than the rigid board solution originally specified — no gaps, no cold bridges.
Commercial developerOur basement conversion needed proper insulation and vapour barrier. Duratite recommended Nexseal LE and the results have been excellent — completely dry walls, no condensation, and the thermal performance is noticeably better. Would definitely use again.
Basement conversion clientIndependently certified products — all documentation supplied with your project pack or on request. Call 01208 832 602.
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Learn more →Book a free site survey and get expert advice on piling and retaining wall insulation — or call us directly on 01208 832 602.
Ground conditions reviewed, U-value calculations performed, fixed-price quotation issued.
Mon–Fri 8am–5pm · 01208 832 602
Real Duratite projects — building type, location, system used and the outcome on site.
SheffieldResidential Development
Sandbanks, DorsetLuxury Residential
DurhamHeritage / MuseumTell us about your building and we’ll recommend the right system — foam, waterproofing or both — surveyed, specified and quoted at no cost.
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