Spray Foam Fire Rating Ireland: Euroclass, TGD B & What You Need to Know

Why Fire Rating Matters for Spray Foam

Spray polyurethane foam is a combustible material. While it does not self-ignite and requires a significant heat source to ignite, once ignited it can contribute to fire spread if left unprotected. This is why Technical Guidance Document B – Fire Safety and fire risk assessments set reaction-to-fire requirements for exposed spray foam surfaces.

Understanding fire ratings is essential because the terminology is complex (Euroclass, s1, d0, and older ratings such as Class 0 and Class 1), the requirements vary by building type and location within the building, and the consequences of getting it wrong are serious — both for life safety and for legal liability. This guide explains the classification systems, what they mean, and how spray foam achieves compliance.

The Euroclass System Explained

The European reaction-to-fire classification system, published in Ireland as I.S. EN 13501-1, rates construction products from A1 to F based on their reaction to fire. This is the classification system used in Technical Guidance Document B – Fire Safety.

For classes A2 to D, additional classifications describe smoke production (s1, s2, s3 — where s1 is lowest) and flaming droplets/particles (d0, d1, d2 — where d0 means none). The complete classification for Nexseal LE with DC315 is B-s1,d0: very limited contribution to fire, low smoke production, and no flaming droplets.

Older National Classifications

Older national classifications (e.g. Class 0 and Class 1) may still appear on product data sheets and in some older specifications. They come from separate test methods, described below, and should not be confused with Euroclasses — when comparing products for an Irish project, ask for the Euroclass to I.S. EN 13501-1.

Fire Propagation Test (BS 476 Part 6)

This test measures the contribution of a material to the growth of a fire. The result is expressed as a fire propagation index (I). A low I value indicates limited contribution to fire. To achieve "Class 0" (see below), the material must achieve an I value of ≤12 and a sub-index i1 of ≤6.

Surface Spread of Flame Test (BS 476 Part 7)

This test measures how far and how fast a flame spreads across the surface of a material. Results are classified as:

• Class 1: Very low flame spread (less than 165mm in 10 minutes)
• Class 2: Low flame spread
• Class 3: Medium flame spread
• Class 4: Rapid flame spread (not acceptable in buildings)

Nexseal LE with DC315 achieves Class 1 surface spread of flame when tested to BS 476 Part 7.

Class 0 and Class 1: What Do They Mean?

Class 0 is a composite national classification — it is NOT a single test result. A material or surface achieves Class 0 if it:

1. Is composed throughout of materials of limited combustibility (A2-s3,d2 or better), OR
2. Is a Class 1 material (BS 476 Part 7) that also satisfies the fire propagation test (BS 476 Part 6) with I ≤12 and i1 ≤6.

Nexseal LE with DC315 intumescent coating achieves Class 0 by route 2: it is Class 1 to BS 476 Part 7 and passes Part 6 with the required fire propagation indices.

Where an older specification calls for Class 0, it has typically been for walls and ceilings in circulation spaces and higher-risk areas. On a current project, the requirement for each surface location is set out as a Euroclass under TGD B and the building's fire safety design.

DC315 Intumescent Coating

DC315 is the critical component that elevates spray foam from Euroclass E (uncoated) to Euroclass B-s1,d0 (coated). Understanding how it works and how it must be applied is important for anyone specifying or installing spray foam insulation.

How DC315 Works

DC315 is a water-based intumescent coating. "Intumescent" means it expands when exposed to heat. At approximately 200°C, the coating begins to swell and form a thick, insulating char layer — expanding to 10–20 times its original thickness. This char layer insulates the underlying spray foam from the fire, dramatically slowing heat transfer and preventing (or significantly delaying) the foam from reaching its ignition temperature.

The intumescent reaction is chemical, not mechanical — it happens automatically when heat is applied and does not require any power, activation, or maintenance. Once applied and dried, DC315 is a passive fire protection system that works for the life of the building.

Application Requirements

DC315 must be applied at the correct coverage rate to achieve the tested fire performance. The standard application is:

• Coverage: 0.45–0.55 litres per m² (approximately 20 wet mils / 0.5mm dry film thickness)
• Application method: Airless spray or roller
• Number of coats: Typically one coat at the required coverage
• Drying time: 2–4 hours (temperature dependent)
• Colour: White (standard) or tinted
• Overcoatability: Can be painted with most topcoats after full cure

The fire performance is tested at the specific coverage rate — applying less coating will not achieve the tested classification. Duratite-approved installers are trained to apply DC315 at the correct rate and verify coverage with wet film thickness gauges during application.

Cost

DC315 intumescent coating is itemised separately on the quotation, depending on the area and application method, because not all applications require it (see "When Is Fire Protection Required?" below).

How Nexseal LE Achieves Fire Compliance

The fire compliance route for Nexseal LE closed-cell spray foam is:

Without DC315 (uncoated): Euroclass E. Acceptable in concealed locations (within wall cavities behind plasterboard, above suspended ceilings with fire-rated tiles) and in buildings exempt from surface spread of flame requirements (some agricultural buildings).

With DC315 (coated): Euroclass B-s1,d0 to I.S. EN 13501-1, and Class 0 under the older national classifications. This is the highest fire classification achievable by any insulation material that is not itself non-combustible. Acceptable for exposed surfaces in virtually all commercial building applications.

Behind non-combustible barrier: Where spray foam is concealed behind a non-combustible barrier (12.5mm plasterboard, cement board, metal cladding), the barrier provides the required surface spread of flame performance and DC315 is not required.

When Is Fire Protection Required?

The fire protection requirement depends on the building type, the location of the spray foam within the building, and whether the foam is exposed or concealed. The following guidance covers the most common commercial scenarios:

Exposed foam in occupied commercial buildings (offices, retail, leisure, education, healthcare): DC315 coating or non-combustible barrier required. The highest reaction-to-fire performance is typically required in escape routes and circulation areas.

Concealed foam behind plasterboard or metal lining: DC315 not usually required if the lining material achieves the required surface spread of flame classification. Your fire safety designer or Building Control Authority will confirm.

Industrial and warehouse buildings: Requirements depend on the fire risk assessment. Many industrial buildings require a high reaction-to-fire classification on wall and ceiling surfaces. DC315 is typically required.

Agricultural buildings: Requirements may be less onerous for buildings remote from the site boundary and not regularly occupied. However, a fire risk assessment is still recommended and the requirement should be confirmed with your local Building Control Authority.

Duratite's technical specification for every project includes a clear statement of the fire protection requirements and whether DC315 is included. If you are unsure about the fire protection requirements for your building, contact Duratite on info@duratite.ie and we will advise.