For architects, structural engineers, and main contractors who specify or procure Monokote fireproofing for the first time, the application process is often less well understood than the product itself. Monokote is widely specified and its fire resistance performance is well documented, but how it actually gets onto a steel frame on a busy commercial construction site, what preparation is required, how quality is controlled during application, and what documentation is produced at the end, are all questions that come up regularly in pre-contract discussions.
This article explains the Monokote spray application process in detail, from initial specification confirmation through to completion documentation. It is written for the commercial construction audience in Ireland: the architects, engineers, project managers, and main contractors who are responsible for making the fireproofing element of a project work within the programme and to the required standard.
FireShield Ireland are the only licensed Monokote applicators in Ireland, covering all 32 counties and throughout Northern Ireland. Our contact details and full service information are at https://fireshieldireland.com/services/monokote-spray/.
Before Application Begins: Specification Confirmation
The application process starts well before anyone sets foot on site. The first step is confirming the full technical specification for the project, which establishes the basis for every subsequent decision about preparation, application, and verification.
The specification confirmation involves identifying the Monokote product grade required for the project. Monokote is available in different grades for different applications, and the appropriate grade depends on the intended use, the exposure conditions, and the fire resistance requirements. For most standard commercial office, retail, and educational projects in Ireland the most commonly specified grades are Monokote MK-6 and MK-6s, both of which are well-established products with extensive certified fire resistance data. For applications with specific requirements such as high humidity environments or particular substrate conditions, other grades may be more appropriate.
The required application thickness for each structural member type on the project is then determined. This is not a single figure for the whole project. Different structural sections have different section factors, which is the ratio of the heated perimeter to the cross-sectional area of the section, and the required Monokote thickness varies with the section factor and the required fire resistance period. A large, heavy universal column with a low section factor requires less Monokote thickness than a small, light universal beam with a high section factor, even if both must achieve the same fire resistance period.
The thickness calculations are carried out using the certified fire resistance data for the specific Monokote grade and the structural sections on the project. We prepare a project-specific thickness schedule covering all section types present on the project and provide this to the main contractor and the structural engineer for review before application begins. This schedule forms the technical basis for the installation and the verification process during application.
Primer compatibility is also confirmed at this stage. If the structural steel has been shop-primed by the fabricator before delivery to site, as is normal on most commercial projects in Ireland, the compatibility of the primer with Monokote must be confirmed in writing before application begins. Applying Monokote over an incompatible primer can result in adhesion failure and delamination, which would require complete removal and reapplication of the coating. We confirm primer compatibility based on the primer specification and provide written confirmation to the main contractor as part of the pre-application documentation.
Site Conditions and Readiness
Monokote application cannot proceed until the site conditions and the state of the structural steel are suitable. There are several criteria that must be met before application begins and these are assessed during a pre-application site visit.
The structural steel must be in position and secured. Monokote is applied to steel that is already erected and fixed in its final position. It cannot be applied to steel that is still being moved or adjusted, and it should not be applied to steel that will be subject to welding or cutting operations after application, as these operations will damage the coating and require repair.
The steel surface must be clean and dry. Surface contamination including oil, grease, dirt, concrete splatter, and loose mill scale must be removed before application. Light mill scale that is firmly adhered to the steel surface is generally acceptable, but loose or laminar mill scale must be removed. The surface must be dry at the time of application and the ambient conditions must be within the limits specified for the product. Applying Monokote to a wet surface or in very cold conditions below the minimum application temperature can affect adhesion and drying performance.
Any structural steel that is not to be coated with Monokote, such as connection plates, baseplate faces, or sections that will be encased in concrete, must be masked before application begins. Similarly, any adjacent surfaces such as metal decking, concrete slabs, or precast elements that are not to receive Monokote must be protected. We carry out this masking and protection work as part of the application process.
Access to all steelwork that requires Monokote must be available. Application requires the operatives to be within a relatively short distance of the steel surface for effective spray application. Where steelwork is at height, as it is on most multi-storey commercial construction projects, appropriate access equipment must be in place. We work with the main contractor to co-ordinate access equipment requirements with the overall site access plan. In some cases we supply our own mobile elevated work platforms; in others we use scaffold or MEWP provided by the main contractor under a co-ordinated access arrangement.
The Application Process
With the specification confirmed, the primer compatibility verified, and the site conditions suitable, the application process can begin. The process involves several stages that are repeated across the project as different areas of steelwork are completed and made available for fireproofing.
Mixing
Monokote is supplied as a dry powder in bags. The powder is loaded into a continuous mixing unit on site and combined with water in the proportions specified by the product manufacturer. The mixed material must be within the consistency range specified for effective application and adhesion. The mixing unit produces a continuous supply of mixed material that is pumped to the spray nozzle.
Spray Application
The mixed Monokote is applied to the steel surface using a spray nozzle connected to the pump by a hose. The operative controls the application rate and the distance from the nozzle to the steel surface to achieve consistent coverage. The product is applied in passes across the steel surface, building up to the required thickness. On sections requiring significant thickness, the application may be carried out in more than one pass with a drying interval between passes if required by the product specification or the ambient conditions.
Surface Finish
Trowelling or screeding of the applied material is not standard practice for Monokote in concealed applications where the surface finish is not critical. The spray-applied finish, which has a characteristic rough texture, is entirely appropriate for steelwork that will be hidden above a suspended ceiling. Where a smoother finish is required in a specific area, the applied material can be trowelled while it is still wet, though this adds time and cost to the application and is generally reserved for locations where the aesthetic is genuinely important.
Thickness Monitoring
Thickness is monitored continuously during application. The operative uses a calibrated pin gauge to check the applied thickness in multiple locations on each section as the application progresses. If the measured thickness is below the required value, additional material is applied immediately. This continuous monitoring ensures that the finished coating meets the specified thickness without requiring significant remedial work after completion.
Quality Verification During and After Application
Formal thickness verification is carried out after application in accordance with the Monokote application specification and any project-specific quality assurance requirements. The process involves taking a specified number of thickness measurements per unit area of coated steel, distributed across the different section types on the project.
The thickness measurements are taken using calibrated pin gauges that penetrate the coating to the steel surface. The pin gauge reading gives the coating thickness at that point. Individual readings that fall below the required minimum are remedied by applying additional Monokote to the deficient area and re-measuring after drying. The overall average thickness across all measurements must meet the specified minimum.
Density verification is carried out alongside thickness verification to confirm that the applied coating has the correct density, which is a measure of the quality of the mixing and application process. Density is determined by calculating the weight of Monokote applied per unit area and comparing this with the theoretical density for the product at the measured thickness. If the calculated density is outside the acceptable range it may indicate that the mixing water content was incorrect or that the application technique needs adjustment.
All thickness and density measurements are recorded on project-specific quality control documentation. The measurement locations, the measured values, and any remedial actions taken are recorded for each area of the project as the work progresses. This live documentation forms the basis of the completion record provided to the main contractor and the building control authority at the end of the project.
Drying and Protection After Application
After application, the Monokote coating must be allowed to dry before it is subjected to significant impact or before adjacent work that could damage the coating begins. The drying time depends on the ambient temperature and humidity conditions and the thickness applied. In typical Irish construction site conditions, where temperatures are moderate and humidity is often relatively high, Monokote applied at standard thicknesses is typically sufficiently dried and hardened to allow careful follow-on trade activity within 24 to 48 hours.
In winter conditions or when the application thickness is greater than normal, longer drying times may be required. We advise on expected drying times at the programme planning stage for each project based on the anticipated site conditions and the specified thicknesses.
Protection of the applied coating from damage during the construction programme is the responsibility of all trades working in the area. Monokote in its dry state is a hard, dense coating that is resistant to normal construction site activity but can be damaged by direct impact, particularly from falling objects, scaffold components, or mechanical plant. Where damage occurs, repair is straightforward using the same product and process as the original application, but damaged areas must be identified, repaired, and re-verified before the project is completed.
We recommend that the main contractor includes protection of applied Monokote in the site rules and the induction briefing for all trades working in areas of completed fireproofing. Early attention to protection of the coating avoids the time and cost of remedial work at the end of the project.
Completion Documentation
At the completion of the Monokote application on a project, we provide a full documentation package covering all the information required for building control sign-off and for inclusion in the building’s health and safety file.
The completion documentation includes the product data sheets and technical information for the specific Monokote grade applied on the project, the fire resistance calculations confirming that the specified thickness achieves the required fire resistance period for each structural section type present on the project, the project-specific thickness schedule showing the required thickness for each section type, the quality control records showing all thickness and density measurements taken during the application, details of any remedial work carried out and the re-verification measurements confirming the remedied areas meet the specification, and a completion certificate signed by FireShield Ireland confirming that the Monokote has been applied to the specified product, at the required thickness, in accordance with the manufacturer’s application specification.
This documentation package is provided in a format suitable for submission to the local authority building control authority in the Republic of Ireland or the district council building control service in Northern Ireland. We are available to liaise directly with building control officers on any queries arising from the documentation and to attend site inspections where the building control authority wishes to view the installed fireproofing before the ceiling installation proceeds.
Programme Planning for Monokote on Commercial Projects
The single most common issue that arises with Monokote fireproofing on commercial construction projects in Ireland is inadequate programme planning. The fireproofing is treated as a minor item, the application is assumed to be straightforward, and the programme window allowed for the work is insufficient for the volume of steel on the project.
The result is a programme conflict between the fireproofing subcontractor and the ceiling installation or other follow-on trades, often at a point in the project when the main contractor is under significant programme pressure. Resolving this conflict inevitably means additional cost and time, and in some cases results in follow-on trades starting before the fireproofing is complete or adequately dried, which causes further problems.
The solution is straightforward. Engage FireShield Ireland at the design or pre-construction stage, provide the structural drawings for a preliminary assessment of the volume of Monokote required and the programme for the application, and incorporate a realistic fireproofing programme window into the overall construction programme before it is finalised. We provide preliminary programme estimates at no cost and are available to attend pre-construction programme meetings to input into the fireproofing programme at the appropriate level of detail.
Contact us to discuss your project at any stage of the design or construction process.
https://fireshieldireland.com/services/monokote-spray/
North: +447340781054 South: +353871128539