HomePiling & Below-Ground Insulation

Sheet Piling • Retaining Walls • Basement Structures

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.

Integral vapour barrier — critical below groundBonds to steel piling, concrete & blockworkBS EN 14315-1 declared values
Nexseal LE closed cell spray foam applied to below-ground retaining wall
Enverge Nexseal LEThe shotcrete-free below-ground build-up · tack-free in 60 seconds
0.027
Nexseal LE lambda W/m·K
78 kPa
Compressive strength BS EN 14315-1
60 sec
Tack-free cure time
BS EN
14315-1 declared values — the basis below ground
Enverge Nexseal LE

The below-ground solution

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.

Completed sheet piling insulation
Spray foam insulation applied to concrete retaining wall below ground level

What the system delivers

Closed-cell structure provides integral vapour barrier — critical below ground
Bonds directly to steel sheet piling, concrete, blockwork and stone
Seamless application — no joints, gaps or cold bridges
Resistant to moisture ingress and ground water pressure
0.027 W/m·K thermal conductivity — lowest in its class
Declared performance independently tested to BS EN 14315-1 — the governing basis below ground
Sheet Piling Insulation

The corrugated profile only spray foam can insulate

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.

Conforms to the Profile

Fills every trough, flange and interlock of the corrugated sheet piling seamlessly — a continuous insulation envelope across the entire piling surface.

Eliminates Cold Bridging

No gaps behind corrugations, no uninsulated steel sections — the thermal bypass paths that defeat board-based systems are gone.

Piling + Infill Together

Applied to both piling and infill panels simultaneously — one continuous layer across every junction.

No Mechanical Fixings

Bonds directly to steel — no fixings that penetrate the structure or create corrosion points.

Below-Ground Structures We Insulate

Every type of retaining structure

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.

Contiguous Piling

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 commercial basements.

Secant Piling

Interlocking concrete piles form an uneven surface rigid boards cannot follow. Nexseal LE conforms to the curved pile faces and fills every interlock.

Sheet Piling

Deeply corrugated steel retaining walls. Foam expands into every corrugation, filling troughs and wrapping flanges to create a seamless thermal envelope.

Diaphragm Walls

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.

Basement Retaining Walls

Cast concrete, blockwork and masonry basement walls. The integral vapour barrier handles constant hydrostatic moisture pressure — no separate tanking membranes or VCLs.

Nationwide Specification Support

Whatever your below-ground structure, Duratite provides specification support and installation Ireland-wide — email info@duratite.ie for a free site survey.

Four Systems Compared

Spray foam vs traditional below-ground insulation

FeatureNexseal LE Spray FoamPIR / Rigid BoardShotcreteTanking Membrane + Board
Thermal Performance0.027 W/m·K0.022 W/m·K~1.0 W/m·K (very poor)0.022 W/m·K + losses at joints
Vapour BarrierIntegral (built-in)Separate VCL requiredNone — porous materialTanking membrane required
Cold BridgesEliminated (seamless)Risk at joints & fixingsMinimal insulation valueRisk at joints & fixings
Irregular SurfacesConforms to any profileCannot follow corrugationsConforms but adds significant weightCannot follow corrugations
Weight AddedMinimal (30–35 kg/m³)LightHeavy (2,300 kg/m³)Moderate
Mechanical FixingsNone requiredAdhesive + fixings neededSteel mesh reinforcementFixings penetrate membrane
Installation SpeedSame day2–3 days2–4 days + curing3–5 days (multi-trade)
Moisture ResistanceClosed-cell — resists ingressAbsorbs moisture over timePorous — absorbs moistureDepends on membrane integrity
Third-party test basisBS EN 14315-1 declared valuesVaries by productNot typically testedVaries by product
Why spray foam below ground: integral vapour barrier (its own VCL — critical where moisture pressure from the surrounding earth is constant); seamless application (no joints, laps or gaps for moisture to penetrate); substrate adhesion (bonds directly to steel, concrete, blockwork, masonry and stone with no fixings, battening or framing); and complex geometry handled (corrugated sheet piling, irregular stone walls, services, penetrations and junctions — no cutting, shaping or fitting).
Piling & Below-Ground Projects

Real projects with main contractors and housebuilders

Duratite projects in the UK and Northern Ireland, delivered with main contractors and housebuilders.

Sheet piling infill insulation Durham Light Infantry Museum Extension

Sheet Piling Infill — DLI Museum Extension, Durham, England

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.

Cook Group LimitedBuild-up to 450mmET150 finish
Retaining wall spray foam insulation project

Contiguous Piling — CG Fry & Sons

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.

CG Fry & SonsUp to 400mmShotcrete-free
Basement insulation spray foam project

Sheet Piling — Bloor Homes, Sheffield, England (via Cook Group)

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 →

Bloor HomesU = 0.18 W/m²KAZ 18-700 piles
From Enquiry to Completion

A proven four-step process

Free site survey, engineered design, professional installation, full documentation.

1

Site Survey

We assess the piling or retaining wall structure, measure areas, review ground conditions and identify access requirements. Free and no-obligation.

2

System Design

We specify thickness, confirm substrate compatibility, perform U-value calculations and produce a fixed-price quotation tailored to your below-ground application.

3

Installation

Manufacturer-trained technicians spray-apply Nexseal LE directly to the piling or retaining wall. The foam bonds seamlessly to steel and concrete substrates.

4

Completion

You receive thickness verification logs, site photographs, warranty documentation and U-value compliance paperwork for your project records.

Why Choose Duratite

Specialist below-ground systems for construction projects

Trusted spray foam insulation specialists — delivering piling and retaining wall insulation systems for construction projects nationwide.

Delivering Projects Since 2015

Duratite has delivered professional spray foam insulation projects for piling, retaining walls and below-ground structures since 2015 and now supports projects across Ireland and Northern Ireland.

1,000+ Commercial Projects

Commercial projects across Ireland and Northern Ireland including sheet piling, retaining walls, basements, warehouses and commercial structures.

Manufacturer-Trained Installers

Our approved installer network is directly trained and certified by Enverge to ensure every installation meets manufacturer specifications.

Full Project Management

From initial survey through to completion and handover — we manage every aspect and coordinate with main contractors on construction projects.

Independently Tested Products

Enverge Nexseal LE performance below ground is evidenced by the manufacturer’s declared values tested to BS EN 14315-1.

Full RAMS Documentation

Complete risk assessments, method statements and project documentation provided for every project. Accepted by main contractors and project supervisors.

Technical Downloads

Data sheets, certificates and specification guides

Nexseal LE BS EN 14315-1 Declared Performance DataBelow-Ground Insulation SpecificationU-value Calculation GuideCondensation Risk Assessment Guide

Independently certified products — all documentation supplied with your project pack or on request. Email info@duratite.ie.

Piling & Below-Ground Insulation FAQs

Common questions answered

Can spray foam be applied to steel sheet piling?
Yes. Nexseal LE closed-cell spray foam bonds directly to steel sheet piling, conforming perfectly to the corrugated profile. It fills every trough, flange and interlock, creating a continuous insulation envelope that eliminates cold bridging through the steel sections.
Why is closed-cell spray foam ideal for below-ground insulation?
Closed-cell spray foam provides an integral vapour barrier, which is critical below ground where moisture pressure from the surrounding earth is constant. The closed-cell structure resists moisture ingress and prevents condensation, while delivering excellent thermal performance at 0.027 W/m·K.
What substrates can Nexseal LE bond to?
Nexseal LE bonds directly to steel sheet piling, poured concrete, precast concrete panels, blockwork, masonry and stone. No mechanical fixings, battening or framing are required. The foam adheres to the substrate on contact, creating a seamless insulation and vapour barrier layer.
How thick should below-ground insulation be?
Typical spray depths range from 25mm to 100mm depending on the target U-value. For basic thermal break and vapour barrier purposes, 25–50mm is common. For full thermal compliance with building regulations, 75–100mm may be specified. We provide free U-value calculations for every project.
Does the spray foam act as a vapour barrier?
Yes. Nexseal LE closed-cell spray foam acts as its own vapour control layer. The closed-cell structure prevents moisture migration from the ground through the wall into habitable spaces. No separate vapour barrier membrane is required, simplifying the build-up and eliminating potential failure points at joints and laps.
Can spray foam insulate the corrugated profile of sheet piling?
Yes. This is one of the key advantages of spray foam over rigid board insulation for sheet piling. Rigid boards cannot conform to the corrugated profile, leaving gaps and cold bridges. Nexseal LE expands to fill every trough, flange and interlock, creating a continuous insulation layer across the entire piling surface.
Is spray foam suitable for basement wall insulation?
Yes. Nexseal LE is widely used for insulating basement walls, foundation walls and below-ground concrete structures. The closed-cell foam provides both thermal insulation and a vapour barrier in one application, bonds directly to concrete without fixings, and conforms to irregular surfaces and around service penetrations.
How long does piling insulation installation take?
Installation timescales depend on the area and access conditions. Spray foam cures in minutes, so there is no drying time. Most piling and retaining wall insulation projects are completed within 1–5 days. Duratite coordinates with main contractors to minimise programme impact.
What warranty is provided?
Nexseal LE carries a manufacturer product warranty. Installations carried out through our approved installer network are covered by a 10-year workmanship guarantee on piling and below-ground insulation projects. Full warranty documentation is included in your completion pack alongside the Nexseal LE BS EN 14315-1 declared performance data and U-value calculations.
Do you work with main contractors on construction projects?
Yes. Duratite regularly works as a specialist subcontractor on construction projects, coordinating with main contractors, structural engineers and project managers. We provide full RAMS documentation, method statements and can work within live construction programmes with minimal disruption to other trades.
What is the difference between contiguous and secant pile insulation?
Contiguous piles have gaps between them that are infilled with concrete or blockwork, creating an irregular surface with multiple cold bridge junctions. Secant piles interlock to form a continuous wall but have an uneven curved face. Both require spray foam rather than rigid board insulation because boards cannot conform to the irregular profiles.
Do you provide below-ground insulation services nationwide?
Yes. Duratite provides piling and below-ground insulation services across Ireland and Northern Ireland. We work on commercial basement projects, infrastructure schemes and residential developments nationwide. Email info@duratite.ie to arrange a free site survey.
Get Expert Below-Ground Insulation

Free site survey — piling and retaining walls nationwide

Book a free site survey and get expert advice on piling and retaining wall insulation — or email us directly at info@duratite.ie.

Integral vapour barrier — critical below groundBonds to steel piling, concrete & blockworkBS EN 14315-1 declared values

Book a free site survey

Ground conditions reviewed, U-value calculations performed, fixed-price quotation issued.

Mon–Fri 8am–5pm · info@duratite.ie

Case Studies

Piling & below-ground insulation case studies

Real Duratite projects — building type, location, system used and the outcome on site.

View all case studies
Free Site Survey

Get a Free Site Survey & Quote

Tell 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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