Home›Boat & Marine Insulation
Closed-cell spray foam that bonds to steel hulls — eliminates condensation, prevents corrosion, keeps you warm year-round. Nexseal LE is applied between ribs, around portholes and across hull plates, creating a seamless thermal and moisture barrier that traditional materials simply cannot match.
Nexseal LE is a closed-cell spray polyurethane foam — performance declared to BS EN 14315-1 — that bonds directly to steel with exceptional adhesion. Applied between ribs, around portholes and across hull plates, it creates a seamless thermal and moisture barrier that traditional materials simply cannot match.
With a lambda value of 0.027 W/m·K, even relatively thin applications deliver outstanding insulation performance — keeping your boat warm in winter and cool in summer while permanently eliminating condensation.
The problem with rockwool, PIR boards & rigid insulation on boats: traditional narrowboat insulation is cut to shape and forced between ribs. But a hull is full of complex geometry — curved hull plates, angled gussets, welded stiffeners, porthole frames, skin fittings and irregular rib spacing. Pre-manufactured boards cannot follow these shapes, leaving air gaps and voids where warm moist air meets cold steel.
These hidden voids are where condensation forms — and where internal hull corrosion begins. Over years, this unseen pitting weakens the steel. By the time it becomes visible during a hull survey, expensive replating may be needed. Spray foam eliminates this entirely by expanding into every contour and bonding to the steel with zero gaps.
From new-build shells to full refits on lived-in boats, Nexseal LE delivers the right solution for every hull type. We work at marinas, boatyards, moorings and dry docks across Ireland and Northern Ireland.
Our most common boat job. Foam sprayed between hull ribs, across cabin sides, under the roof deck and around portholes — 25–50mm between ribs, trimmed flush for lining.
Larger surface areas lose more heat. We spray hull plates and between timber battens, creating a flat, plywood-ready surface. Typically 35–75mm depending on liveaboard or leisure use.
The ideal time to spray — clean steel, easy access, no obstructions. We work with boatbuilders across Ireland and Northern Ireland, spraying shells before fit-out, trimmed flush so lining starts immediately.
We strip failed rockwool or damp PIR, inspect the hull for corrosion, treat any pitting, then foam the entire hull — warmer, drier, fully protected.
Steel boats lose heat rapidly through their thin hull plates. When warm cabin air meets cold steel, moisture condenses — dripping from ceilings, running down walls, soaking timber linings and corroding the hull from inside. Here is how Nexseal LE solves every aspect of the problem.
Foam raises the roof deck temperature above the dew point. No cold steel surface means no condensation dripping onto bedding, furnishings or electronics.
Hull sides are where most condensation forms. Foam bonds to the hull plate and fills behind every rib, eliminating the cold surfaces that cause running water.
Condensation trapped behind traditional insulation corrodes the hull where you cannot see it. Foam seals the steel surface completely, keeping moisture off the plate.
Persistent dampness causes mould and mildew, triggering respiratory problems. Eliminating condensation creates a dry, healthy environment — critical for liveaboards aboard 365 days a year.
Portholes and windows are notorious cold bridges. Foam wraps around frames and fills the irregular gaps boards cannot reach, stopping condensation rings around every opening.
In summer, foam blocks radiant heat through the steel. In winter, it retains stove heat far better than traditional insulation. Less fuel, less condensation, every season.
Spray foam has become the insulation of choice for narrowboat builders and refitters across Ireland and Northern Ireland. Hull corrosion protection: foam seals the internal hull surface from moisture, preventing the hidden pitting that shortens a narrowboat’s life — your hull survey will show clean steel where foam has been applied.
At lambda 0.027 W/m·K, 50mm of Nexseal LE outperforms 100mm of rockwool or 75mm of PIR board — critical in boats where every millimetre of internal width matters. And closed-cell foam is its own vapour barrier: no separate membrane to install, puncture or fit incorrectly.
See how Nexseal LE closed-cell spray foam compares to the traditional insulation methods commonly used in narrowboats and canal boats.
| Property | Nexseal LE Spray Foam | Traditional (Rockwool / PIR / Rigid Boards) |
|---|---|---|
| Adhesion to Steel | Bonds permanently to hull | Friction fit, gaps at ribs |
| Condensation Control | 100% — integral vapour barrier | Condensation forms behind insulation |
| Hull Corrosion Risk | Eliminated — steel sealed from moisture | High — trapped moisture corrodes hull |
| Lambda (W/m·K) | 0.027 | 0.034–0.044 |
| Water Absorption | Nil — closed-cell structure | Absorbs moisture, loses performance |
| Coverage Around Ribs | Fills every profile seamlessly | Cut to fit, gaps inevitable |
| Porthole/Window Sealing | Wraps around frames completely | Gaps around windows are common |
| Longevity | Lifetime of vessel — no degradation | Sags and degrades within 5–15 years |
| Installation Speed | Full boat in 1–2 days | Several days of cutting and fitting |
| Structural Contribution | Adds rigidity to hull plates | No structural benefit |
Four steps get your narrowboat insulated quickly and professionally — at a marina, boatyard or your own mooring.
We assess your vessel — hull type, length, rib spacing, current insulation, access, and whether it is a new build or refit. This determines the right approach and thickness.
We specify the Nexseal LE thickness, any timber batten framework needed, and provide a fixed-price quotation based on your boat’s dimensions. No hidden extras.
Trained applicators spray Nexseal LE directly to the steel hull, walls and roof deck. Foam fills between ribs, around portholes and into every irregular profile. Cures in minutes.
Foam is trimmed flush with the ribs. You receive a completion pack with thickness verification and datasheets. The boat is ready for plywood, tongue-and-groove or your chosen lining.
Narrowboat and widebeam insulation projects completed by our approved installer network across Ireland and Northern Ireland.
A bare steel shell foamed throughout before fit-out. Nexseal LE at 40mm between ribs, trimmed flush, plus 15mm over ribs for continuous coverage. Owner reported zero condensation from the first winter aboard.
Complete strip-out of failed rockwool that had caused severe condensation for years. Hull inspected, treated for minor pitting, then foamed throughout. “A completely different boat — dry, warm, no more condensation at all.”
A 12ft-beam vessel converted for permanent residential use. Timber battens fixed to the hull, foamed to 65mm between battens with full roof coverage. Lining went straight over the foam — the owner lives aboard year-round in complete comfort.
Nexseal LE closed-cell spray foam applied to narrowboat, canal boat and widebeam hulls — bonding directly to steel between ribs.
As an authorised distributor of Enverge spray foam systems, Duratite supplies the products and technical backing; installation is carried out by our network of trained, approved applicators.
Factory-direct supply of Nexseal LE with full manufacturer backing, technical support and warranty coverage.
Every installer in our network is factory-trained on Enverge equipment and holds current spray foam qualifications.
No surprises. Every project is surveyed and quoted at a fixed price before any work begins. Free surveys across Ireland and Northern Ireland.
Nexseal LE performance is declared to I.S. EN 14315-1 — backed by a 25-year manufacturer-backed product warranty.
Duratite has delivered spray foam insulation since 2015 across commercial, residential, agricultural and marine applications.
We spray boats at marinas, boatyards, moorings and dry docks across Ireland and Northern Ireland.
Independently certified products — tested to published standards. Full project packs supplied on request — email info@duratite.ie.
Common questions about spray foam insulation for narrowboats, canal boats and marine vessels.
Anti-condensation protection and full container conversions with Nexseal LE — eliminate condensation rain inside shipping containers.
Learn more →CommercialLarge-scale commercial warehouse and industrial unit insulation — cut energy costs and stop condensation.
Learn more →AviationAircraft hangars and large steel structures insulated with spray foam.
Learn more →WallsSpray foam between timber studs for maximum thermal performance.
Learn more →LeisureReduce pool heat loss by up to 50% with closed-cell spray foam.
Learn more →HubExplore all commercial spray foam insulation applications, systems and sectors.
Learn more →Book a free survey or request a callback from our marine insulation team. We work at marinas, boatyards and moorings across Ireland and Northern Ireland — and your boat does not need to leave the water for internal hull insulation.
Fixed-price quotation based on your boat’s dimensions — no hidden extras.
Mon–Fri 8am–5pm · info@duratite.ie
Tell us about your building and we’ll recommend the right system — foam, waterproofing or both — surveyed, specified and quoted at no cost.
Reduce heat loss by up to 50% with closed cell spray foam.
Eliminate condensation rain inside shipping containers.
Stop condensation dripping from corrugated metal roofs.
Cut energy costs and stop condensation in warehouses.
Explore all commercial spray foam insulation applications.
Airtight thermal envelope for modular and portable buildings.
