Door Upgrade Coatings

Door upgrade coating systems involve the application of specialized coatings, such as intumescent paints and fire-resistant varnishes, which enhance the fire performance of a door. These coatings react to heat by expanding, forming a char layer that acts as an insulator, slowing down the spread of fire and smoke. This process not only protects the door itself but also provides critical additional time for occupants to evacuate and for emergency services to respond.

Top Features to Consider When Upgrading Doors

Material Compatibility:

Not every door is suitable for fire-resistant upgrades. Hollow-core doors or those made from lightweight materials may not achieve the necessary fire resistance even with coatings. The best candidates for upgrading are solid, well-constructed doors, particularly those made of hardwood or solid-core materials. Before proceeding with an upgrade, it is crucial to assess the door's material and structure. For example, doors with a minimum thickness of 35mm and constructed from dense hardwood are ideal for achieving enhanced fire resistance when treated with intumescent paint or varnish.

Door Types and Characteristics:

• Solid Doors: Doors that are solid, with a minimum thickness of 6mm and a compressed core, are generally suitable for upgrading. These doors often feature veneer faces bonded to either side of the core, which may be either flush or moulded​.
• Seasoned or Old Doors: Older, well-seasoned doors with substantial frames (35mm or thicker) and solid panels (10mm or thicker) are good candidates for upgrading. Such doors are typically made from sturdy hardwoods or other resilient materials. However, for doors with thinner panels (e.g., 8mm), it is recommended to insert additional “sacrificial” ply panels to increase the total thickness​​.
• Modern Softwood Doors: Many modern doors, particularly those made from softwood, are often not suitable for upgrading. These doors may lack the necessary integrity to withstand fire, as they tend to be thinner, lighter, and prone to warping. Only old, well-seasoned softwood doors might be upgraded, but even then, only under certain conditions where the frame can afford a loss of 10mm due to charring​. If you are unsure of the suitability of your door, contact Rawlins’ technical team for help and advice.

Incompatibility Issues:

• Hollow Core Doors: Doors with hollow cores, which are common in many modern constructions, cannot be upgraded to meet fire resistance standards. The lack of material inside these doors makes them vulnerable to rapid collapse during a fire, thus disqualifying them from any fire-resistance treatment​​.
• Structural Integrity: A crucial factor in determining a door's suitability for upgrading is its ability to maintain structural integrity when subjected to heat. Doors that cannot afford the necessary material loss due to charring (e.g., 2mm to 10mm depending on the door type) should not be considered for upgrading​​.

Compatibility with Door Hardware

The effectiveness of a fire-resistant door upgrade extends beyond the door itself to include the hardware, such as hinges, locks, and seals. It is important to ensure that the hardware is compatible with the fire-resistant coating and that it meets fire safety standards. For example, fire-rated hinges and locks should be used in conjunction with intumescent coatings to ensure the entire door assembly can withstand fire for the required duration. Additionally, intumescent strips should be installed around the door edges to prevent the passage of smoke and flames.

• Intumescent Strips: Intumescent strips are an essential component of a fire-resistant door assembly. These strips are fitted around the edges of the door and expand when exposed to heat, sealing the gap between the door and the frame to prevent the passage of smoke and fire. Intumescent strips are available in various sizes and colours to match the door and frame, and they are critical for ensuring that the upgraded door meets the required fire resistance rating.
• Fire-Resistant Door Seals: Fire-resistant door seals work in conjunction with intumescent strips to provide a comprehensive barrier against fire and smoke. These seals are typically installed along the edges of the door and the door frame, creating an airtight seal when the door is closed. In the event of a fire, the seals expand, filling any gaps and preventing the spread of flames and smoke into adjacent compartments. Proper installation of door seals is crucial for maintaining the integrity of the fire-resistant door upgrade.
• Fire-Rated Hinges and Locks: The hardware used on fire-resistant doors must also be capable of withstanding high temperatures without failing. Fire-rated hinges and locks are designed to maintain their structural integrity during a fire, ensuring that the door remains functional for the required period. When upgrading doors, it is important to replace any existing hardware with fire-rated alternatives to ensure the entire assembly meets fire safety standards. This includes using intumescent pads behind hinges and lock cases to protect the surrounding wood from heat damage.
• Intumescent Mastic: Intumescent mastic is used to seal joints and gaps around the door frame, particularly where the frame meets the wall. This mastic expands when exposed to heat, creating a fire-resistant barrier that prevents the passage of fire and smoke. It is especially useful in areas where the door frame is set into a wall with cavities or where there are gaps between the frame and the surrounding structure. Proper application of intumescent mastic is essential for ensuring that the fire-resistant door assembly performs as intended.
• Fire-Resistant Paint for Frames: To provide complete fire protection, it is important to treat not only the door itself but also the door frame. Applying a fire- resistant paint to the frame ensures that it can withstand fire for the same duration as the door, preventing the fire from bypassing the door through the frame. This is particularly important in older buildings where the door frames may be made of wood or other combustible materials. Fire-resistant paints are available in a variety of finishes, allowing them to be matched to the existing decor.

Achievable Fire Resistance Rating

The level of fire resistance that can be achieved depends on the product used and the existing door’s construction. Upgrading doors typically aims to provide 30 minutes of fire resistance - in some cases a higher level of fire protection is possible, please contact Rawlins' technical team for further assistance. For example, a solid oak door treated with multiple coats of intumescent varnish can achieve a fire resistance rating of 30 minutes. This rating ensures that the door will prevent the spread of fire and smoke for a sufficient period, allowing occupants to evacuate safely and reducing the potential for fire to spread to other areas of the building.

Compliance with Local Regulations and Building Codes

Upgraded doors must comply with local fire safety regulations and building codes. In the UK, this means adhering to the guidelines set out in Approved Document B of the Building Regulations, which specifies the fire resistance requirements for doors based on the building's use and occupancy. It is essential to consult with fire safety professionals and building control officers to ensure that the upgraded doors meet all necessary regulatory requirements.

Type of Fire-Resistant Coating

The choice of coating is a critical factor in the upgrading process. Intumescent paints are available for both opaque and clear finishes. They are ideal for scenarios where a specific aesthetic is required, such as in commercial properties where maintaining a consistent colour scheme is important. On the other hand, fire-resistant varnishes are suitable for preserving the natural look of wood, making them ideal for heritage properties or high-end residential buildings. The coating type should be chosen based on the desired finish, the material of the door, and the level of fire resistance required.

Application Method and Process

Applying fire-resistant coatings is a detailed process that requires precision. The effectiveness of the coating depends on the thickness and uniformity of application. Typically, multiple coats are needed to achieve the desired fire resistance with each layer being allowed to dry thoroughly before applying the next. 

Situational Examples and Applications

Heritage and Listed Buildings

Heritage buildings often face strict regulations regarding the preservation of original architectural features, including doors. In such cases, replacing original wooden doors with modern fire doors may be prohibited or undesirable. Upgrading these doors with fire-resistant coatings offers a solution that maintains the building's historical integrity while enhancing safety. For example, in a listed Victorian mansion, providing the original oak doors meet the relevant minimum requirements detailed by the manufacturer, they can be treated with a clear intumescent varnish that preserves their appearance while providing up to 30 minutes of fire resistance. This method allows property owners to comply with fire safety regulations without compromising the building's character.

Commercial Office Buildings

In large commercial office buildings, particularly those constructed before modern fire regulations were established, many internal doors may not meet current fire safety standards. Replacing every non-compliant door with a certified fire door can be prohibitively expensive and disruptive to operations. Depending on the fire action plan for the building, and in accordance with your Building Control officer, if the doors are suitable then they may be able to be treated with fire resistant coatings. This may save money over installing new doors that comply with fire regulations, particularly in critical areas like stairwells and corridors, but only if the existing doors are suitable.

Residential Blocks and Multi-Occupancy Buildings

In residential blocks, especially older ones undergoing refurbishment, ensuring that all doors meet fire safety standards is vital for protecting residents. In such settings, upgrading existing doors with fire-resistant coatings is often the most practical solution. For instance, in a block of flats built in the 1960s, where the internal doors are solid but lack fire certification, applying a fire-resistant varnish can upgrade these doors to meet modern fire safety requirements. This approach is particularly effective in communal areas and escape routes, where fire doors are critical for containing potential fires and ensuring safe egress for residents.

Healthcare Facilities and Hospitals

In healthcare settings, such as hospitals and care homes, the safety of patients and staff is paramount. The doors in these facilities, particularly those leading to patient rooms and operating theatres, must be capable of withstanding fire to prevent the spread of smoke and flames. Upgrading these doors with intumescent coatings can provide the necessary protection without the need to disrupt hospital operations. For example, solid-core doors in a hospital can be treated with a fire-resistant varnish, ensuring they can withstand fire for at least 30 minutes, thereby protecting vulnerable patients and allowing staff to manage evacuations safely.

Educational Institutions

Schools, universities, and other educational institutions have stringent fire safety requirements due to the high occupancy and the need to protect students and staff. Doors in these buildings, especially in classrooms, laboratories, and libraries, must be upgraded to ensure they can withstand fire for a critical period. Applying fire-resistant coatings to these doors ensures compliance with safety regulations while maintaining the aesthetic appeal of the institution. For example, a university with a mix of modern and historical buildings can upgrade all internal doors to 30-minute fire resistance by applying intumescent paint, providing a uniform level of safety across the campus.

FAQs

Can all doors be upgraded to be fire-resistant?

No, not all doors are suitable for upgrading to achieve significant fire resistance. Hollow-core doors, lightweight or very thin doors, and doors made from certain materials may not be able to achieve the necessary fire resistance even with the application of fire-resistant coatings. Generally, the best candidates for upgrading are solid, well-constructed doors made of hardwood or solid-core materials with a minimum thickness of 35mm.

How is a fire-resistant coating applied?

Fire-resistant coatings are typically applied in multiple layers using brushes, rollers, or sprayers. The exact application method and number of coats required depend on the product and the desired level of fire resistance.

What fire resistance rating can be achieved with these coatings?

The level of fire resistance that can be achieved depends on the specific product used and the construction of the door. For example, Thermoguard Timbercoat Intumescent Paint can upgrade a solid wood door to provide 30 minutes of fire resistance when applied according to the manufacturer's instructions. Higher fire resistance ratings may be achievable with additional coats or in combination with other fire-resistant materials - contact the technical team for further assistance.

Do upgraded doors need additional fire protection measures?

Yes, upgraded doors must be complemented with additional fire protection measures, such as intumescent strips, fire seals, and fire-rated hardware, to ensure comprehensive fire safety and gain approval from Building Control. These accessories are crucial for preventing the spread of fire and smoke through gaps around the door, ensuring that the entire door assembly meets the required fire resistance rating.

Is there any way to verify that the door has been upgraded correctly?

After applying a fire-resistant coating, it is advisable to have the door inspected by a fire safety professional to ensure it meets the required standards. Certification from the coating manufacturer may also be available for authority-approved projects. Additionally, regular inspections should be conducted to ensure that the coating remains intact and that all fire protection measures are functioning as intended.

What maintenance is required for fire-resistant doors?

Maintenance requirements vary depending on the product used. Generally, fire-resistant coatings are durable and require minimal upkeep. However, it is important to inspect the doors regularly for any signs of wear or damage. In high-traffic areas, reapplication of the coating may be necessary every few years to maintain the required level of fire resistance. Regular maintenance also includes checking that all associated fire protection measures, such as intumescent strips and fire seals, are in good condition.

Can fire-resistant coatings be used on exterior doors?

Some fire-resistant coatings are suitable for use on exterior doors, but it is essential to choose a product specifically designed for that purpose. Exterior-grade fire-resistant coatings are formulated to withstand weather conditions while still providing effective fire protection. When upgrading exterior doors, it is important to consider both fire resistance and environmental durability to ensure long-term performance. If you have an exterior door you’d like to upgrade, please contact the technical team for more assistance.

Contact Rawlins Paints' Technical Support Team for Expert Advice

For further assistance with selecting and applying fire-resistant coatings, or to ensure compliance with fire safety regulations, contact Rawlins Paints' technical support team. Our experts are on hand to provide tailored advice and support for your specific project needs.