What are intumescent painting services?

Intumescent painting services apply a specialist passive fire protection coating to structural steel. The coating expands when exposed to heat above 200°C, forming an insulating char layer that slows heat transfer to the steel and maintains structural integrity for the specified fire resistance period — typically 30, 60, 90 or 120 minutes. A complete intumescent painting service includes shot blasting the steel to Sa 2.5, applying a compatible primer, the intumescent mid-coat, and a protective topcoat.

What surface preparation is required before intumescent painting services?

All intumescent coating manufacturers specify a minimum surface cleanliness of ISO 8501-1 Sa 2.5 (near-white metal) and a surface profile of Rz 40–70 microns before primer application. Shot blasting is the standard method for achieving this. Applying intumescent painting services over inadequately prepared steel will cause adhesion failure and void the coating warranty.

Do you provide shot blasting and intumescent painting services as a combined service?

Yes. We offer combined shot blasting and intumescent painting services in a single mobilisation. Our shot blasting team and intumescent painting team work simultaneously on site — one crew blasting ahead, another coating behind. This eliminates the risk of flash rusting between trades and reduces overall programme time and cost.

Can intumescent painting services be carried out on site?

Yes. We carry out intumescent painting services on site using mobile airless spray equipment and elevated work platforms including scissor lifts and boom lifts. No dismantling or transportation of steelwork is required. On-site application is standard practice for structural steel frames that are already erected.

What fire resistance periods can your intumescent painting services achieve?

Our intumescent painting services can achieve 30, 60, 90 and 120 minute fire resistance periods depending on the structural engineer's specification, the steel section factor (Hp/A), and the intumescent product selected.

What regulations require intumescent painting services on structural steel?

Approved Document B (Fire Safety) of the Building Regulations in England and Wales requires structural steelwork in most commercial, industrial and multi-storey residential buildings to achieve a specified fire resistance period. Equivalent regulations apply in Scotland and Northern Ireland. Intumescent painting services are the most common method of achieving compliance for exposed structural steelwork.

How long does intumescent paint last on structural steel?

When applied correctly over a Sa 2.5 blast-cleaned surface with a compatible primer and topcoat, intumescent paint systems are designed to last 25–30 years in internal environments and 10–15 years in exposed environments before maintenance is required. Regular inspection every 5 years is recommended.

What is the difference between intumescent painting services and board-based fire protection?

Intumescent painting services apply a thin-film coating (typically 1–3 mm DFT) directly to the steel surface. Unlike board-based systems such as Fendolite or Vermiculux, intumescent paint preserves the architectural appearance of the steelwork, adds negligible weight, and can be applied on site without dismantling the structure.

How much do intumescent painting services cost per m²?

The cost of intumescent painting services depends on the fire resistance period, steel section factor, access requirements, structure size, and location. As a guide, a complete three-coat system for 60-minute fire protection on a standard industrial building typically ranges from £18–£45 per m² of steel surface area. Contact us for a free site visit and written quotation.

Do you cover the whole of the UK for intumescent painting services?

Yes. Our mobile intumescent painting services team covers the whole of the UK, including England, Scotland and Wales. We have completed projects across the Midlands, Yorkshire, the North West, and the South East. We can mobilise within 48 hours of enquiry.

Intumescent Paint for Structural Steel

This page explains the assessed blasting-and-painting route for structural steel requiring an intumescent coating system. Preparation, primer, intumescent mid-coat and protective topcoat need to align with the actual project specification, steel section factor and required fire-resistance period.

Plan the Steel Preparation and Coating Interface

The steel's condition, the proposed coating system, access, inspection needs and handover sequence all matter. Where abrasive preparation is required, the project specification should determine the agreed cleanliness and profile before the compatible coating system is selected and applied.

Recorded Project Context

The approved HB Tunnelling case study records abrasive blasting, immediate primer and intumescent fire-protective painting at a Doncaster warehouse refurbishment. Its location and project facts are specific to that documented record; read the Doncaster case study for the full approved context.

Discuss an intumescent-paint-for-steel scope with UK Shot Blasting Services. Call 07721 375756 or request a site visit.