6 Intumescent Fireproofing Mistakes and How to Avoid Them

When it comes to fire protection in buildings, intumescent coatings serve as a critical line of defence. These specialized coatings create an insulating barrier when exposed to high temperatures, protecting structural steel and other materials from fire damage. However, even the most advanced intumescent fireproofing systems can fail if not applied correctly. 

Understanding why these failures occur and how to prevent them is essential for contractors, architects, and building owners who prioritize life safety and structural integrity. 

What is the Cost of Application Errors?

Intumescent fireproofing failures not only compromise building codes but also put lives at risk. When these protective coatings fail during a fire, structural elements can lose their load-bearing capacity much faster than designed, leading to catastrophic building collapse. 

The good news? Most failures are entirely preventable.

They stem from seven common application mistakes that can be avoided with proper training, quality control, and attention to detail. 

1. Inadequate Surface Preparation

Many applicators underestimate the importance of surface preparation. Steel surfaces contaminated with rust, mill scale, oil, grease or old coatings prevent proper adhesion of intumescent systems. 

Why it happens:

• Time and cost pressures to speed up application
• Lack of understanding about adhesion requirements
• Inadequate surface inspection before coating
• Using improper cleaning methods

This poor surface preparation leads to delamination, where the coating separates from the substrate. During a fire, this allows steel to heat rapidly and fail prematurely.

2. Skipping Required Primers

Many intumescent systems require specific primers for proper adhesion, corrosion protection, or compatibility. Skipping this step creates a fundamental system weakness.

Why It Happens:

• Cost-cutting measures
• Misunderstanding system requirements
• Assuming all primers are interchangeable
• Project delays create pressure to reduce steps

  3.  Improper Dry Film Thickness

Instumescent coatings must achieve a specific dry film thickness to provide the rated fire protection. Under-application is one of the most common causes of system failure. 

Why it happens:

• Pressure to reduce material costs
• Inadequate application training
• Improper spray equipment settings
• Insufficient quality control during application

Insufficient thickness means inadequate expansion during fire exposure. A coating specified for multi-hour fire protection might only provide minimal protection if applied too thin.

4. Unsuitable Environmental Conditions

Intumescent fireproofing systems have specific environmental windows for application. Temperature, humidity, and substrate conditions all affect coating performance and cure. 

Why It Happens:

• Project schedule pressures
• Inadequate environmental monitoring
• Working in partially enclosed structures with variable conditions

Applying in the wrong conditions causes poor curing, moisture entrapment, surface defects like bubbling, and reduced fire performance. Coatings may appear acceptable but lack the proper chemical cure necessary for fire protection.

5. Poor Detailing 

Structural connections, joints, welds, and penetrations are critical areas that often receive inadequate coating coverage. These complex geometries require special attention.

Why It Happens:

• Difficult access in tight spaces
• Rush to complete large, visible areas
• Lack of detail-oriented training
• Inadequate inspection of complex areas

These locations are often the most vulnerable during fire exposure. Unprotected connections can fail first, which leads to a progressive collapse. 

6. Inadequate Curing Protection

After application, intumescent coatings require proper curing conditions and protection from damage. Construction activity, weather exposure, or premature loading can compromise recently applied systems.

Why It Happens:

• Schedule pressure to proceed with subsequent trades
• Inadequate site coordination
• Not understanding cure time requirements

Disturbing coatings during cure can cause surface damage, contamination, reduced fire performance, and lead to costly repairs or reapplication.

What is the Best Defence Against Failure?

Preventing intumescent fireproofing failures requires a comprehensive quality assurance program that includes:

Pre-Application Planning:

• Material selection appropriate for exposure conditions
• Detailed application specifications
• Environmental monitoring plan
• Applicator training and certification verification

During Application:

• Continuous inspection and documentation
• Environmental condition monitoring
• Batch testing and mixing verification

Post-Application:

• Final inspection of all areas, including details
• Photography documentation
• Third-party testing when required
• Proper cure time before building occupancy

Sunanda’s High-Performance Fire Protection Solutions

Sunanda Global offers specialized intumescent paint systems designed for diverse fire protection requirements across industrial and commercial projects.

SUNNOFLAME IP – Water-Based Intumescent Paint

This water-based system produces minimal odour and low VOC emissions.

SUNNOFLAME IP applies like regular paint and dries quickly. It provides a smooth architectural finish that accepts topcoats for colour matching to design specifications.

SUNNOFLAME IP 1709 – Epoxy-Based Intumescent Paint

This epoxy-based system provides durability and fire protection under harsh conditions. It is specifically formulated for hydrocarbon fire exposure in aggressive industrial settings.

SUNNOFLAME IP 1709 is an epoxy formulation that combines fire protection with corrosion resistance in a single system.

SUNNOFLAME MORTAR – Fire Barrier Mortar

SUNNOFLAME MORTAR is a dry white powder consisting of inorganic compounds and perlite, used to reinstate the fire resistance performance of flexible and rigid walls and floor constructions, where they are penetrated by various cables and metallic pipes.

It has a high degree of mechanical resistance, and the seal is load-bearing without reinforcement. 

Partner with Sunanda for Fireproofing Excellence

With over 45 years of experience in Indian industrial construction, Sunanda Global is a trusted fireproofing and waterproofing company and manufacturer of ISO 9001:2015-certified, R&D-driven products. Our solutions cater to diverse sectors, from pharma to petrochemicals, and are designed to meet Indian safety standards while promoting sustainability. Moreover, Sunanda Global provides full support: from technical advice to vetted partners.

Contact Sunanda Global for fireproofing that combines scientific innovation, safety, and reliable performance.

FAQs

Q1. What is the most common cause of intumescent coating failure?

Inadequate surface preparation is the leading cause of intumescent coating failure. When steel is not properly cleaned to remove rust, mill scale, and contaminants, the coating cannot achieve proper adhesion, resulting delamination during fire exposure when protection is most critical.

Q2. Can intumescent coatings be applied in cold weather conditions?

Most intumescent systems require application within specific temperature ranges and humidity levels. Cold weather application is possible with proper environmental controls such as heated enclosures, but never apply when temperatures fall below manufacturer minimums as this prevents proper curing.

Q3.  What is the difference between intumescent paint and fireproof mortar?

Intumescent paint is a thin-film coating that expands when heated to create an insulating char layer, ideal for large steel surfaces. Fireproof mortars are thicker, cementitious materials used for complex details, penetrations, and areas requiring impact resistance or dimensional build-up.

Q4. How long does intumescent coating need to cure before construction can continue?

Cure times vary by product and environmental conditions. Fast-cure formulations may reduce these times significantly. Always verify cure requirements in technical data sheets and protect coatings from damage, moisture, and construction activity during the entire curing period.

Q5. Why is dry film thickness so important for fire protection?

Dry film thickness directly determines the coating’s expansion capacity and insulation performance during fire. Insufficient thickness means inadequate expansion, significantly reducing fire resistance ratings and potentially allowing structural failure well before the designed protection period.