{"id":206734,"date":"2023-10-16T06:00:26","date_gmt":"2023-10-16T10:00:26","guid":{"rendered":"https:\/\/www.constructionspecifier.com\/?p=206734"},"modified":"2023-10-12T17:38:40","modified_gmt":"2023-10-12T21:38:40","slug":"standardizing-guidelines-to-specify-ifrms","status":"publish","type":"post","link":"https:\/\/www.constructionspecifier.com\/standardizing-guidelines-to-specify-ifrms\/","title":{"rendered":"Standardizing guidelines to specify IFRMs"},"content":{"rendered":"
\"Photo<\/a>
Photo courtesy Sustainable Living Innovations. <\/em><\/span><\/figcaption><\/figure>\n

By Max Tritremmel<\/strong><\/p>\n

Architecturally exposed structural steel (AESS) (Figure 1) is a popular design feature that can complement the strength and beauty of steel to other architectural features. However, as a key part of what provides the integrity of the structure, that steel must be protected to ensure it retains its strength in the event of a catastrophic fire.<\/p>\n

Traditional fire protection materials were sprayed fire-resistive materials (SFRMs), commonly referred to as cementitious fire protection (CFM), which were not well-suited to complement the beauty of exposed steel. The unsightly finishes often required concealment in the form of drop ceilings, sheetrock, or covers to ensure architects could meet their aesthetic design objectives. The material is also messy when left uncovered, contributing to a large amount of dust in spaces that creates a constant cleaning nuisance, and can quickly clog HVAC filters.<\/p>\n

The advent of intumescent fire-resistive materials (IFRMs), which are smooth in appearance, finally allowed for the expression of exposed steel in new and creative ways, and new material innovations continue to support this change. IFRMs allow designers to strip away the unnecessary elements that were common in construction in the last century and create new, simpler buildings\u2014delivered with greater speed, total cost efficiency, and sleeker appearances.<\/p>\n

Given the emphasis on beauty with AESS, it is to be noted, no single global standard exists for specifying the finish appearance of the IFRM coating for this element in building design. The American Institute of Steel Construction (AISC) offers a detailed category system for specifying the overall finish quality of exposed steel, based on member visibility, viewing distance, location, lighting, coatings, style, adjacency, and cost.1<\/sup> However, the AISC guidelines make only minimal reference to IFRM coatings in the AESS category system, generally referring to these coatings as \u201csmooth.\u201d Establishing better guidance for the appearance of IFRMs on exposed structural steel will help the construction and coatings industries deliver better outcomes for AESS.<\/strong><\/p>\n

\"Figure<\/a>
Figure 1<\/b> Intumescent fire-resistive materials (IFRMs) offer an attractive, architecturally pleasing finish compared to bulky cementitious sprayed fire-resistive materials (SFRMs), enabling the use of architecturally exposed structural steel (AESS) throughout buildings. <\/span>Photos courtesy The Sherwin-Williams Company. <\/em><\/span><\/figcaption><\/figure>\n

Current IFRM finish standards<\/strong><\/p>\n

Historically, the fire protection industry has concerned itself with performance defined by code compliance, rather than the finish. Architects and contractors bear the shared responsibility for the look and finish quality of AESS surfaces, as well as compliance with those codes. In the absence of a defined coating standard for the appearance of IFRMs applied to AESS, they have no real objective or straightforward way to define the look of an AESS finish in advance for the building owner to approve.<\/p>\n

<\/p>\n

\"Figure<\/a>
Figure 2<\/b> The type and thickness of the intumescent fire-resistive material (IFRM) used on architecturally exposed structural steel (AESS) influences the texture of the final finish, with epoxies having a thicker, more textured appearance than water- and solvent-based acrylic intumescent coatings.<\/span>Photo courtesy <\/em><\/span><\/figcaption><\/figure>\n

With no overarching standard to reference, some architects initially turned to makeshift standards, such as the GA-214-2021, Levels of Finish for Gypsum Panel Products<\/em> guidelines.2<\/sup> It made sense when considering the adjacent role of gypsum wallboard in fire containment and the interaction of it in wall systems when attaching to and encasing SFRMs. While GA-214-2021 may provide a useful analogue for finish quality; the materials, processes, and tools used to apply gypsum-based products are quite different from those used with IFRMs applied to exposed steel surfaces and, ultimately, the correlation was poor with the desired outcomes often being off the mark.<\/p>\n

An important reason is, it is not aligned with AESS and does not take observer distance into account to differentiate between the levels. Further, the references to tape and the number of coats of compound make differentiating between GA-214 Levels 2 and 4 difficult for IFRMs as the addition of more coats would not necessarily ameliorate appearance in the case of IFRMs. Lastly, the premium Level 5 finish requires a skim coat of a differentiated material, something which is not permitted in the fire protection world without a corresponding fire test with the topping material.<\/p>\n

In Europe, where IFRMs have surpassed SFRMs in cellulosic fire protection applications, the guidance is a bit more advanced and closer to the mark. The Association for Specialist Fire Protection (ASFP) Technical Guidance Document 16 (TGD 16), Code of Practice for Off-Site Applied Thin Film Intumescent Coatings<\/em>,3<\/sup> outlines three categories of finishes\u2014basic, decorative, and bespoke\u2014and promotes cost-saving, off-site IFRM applications so pre-coated beams arrive at the jobsite ready for assembly.<\/p>\n

This ASFP standard is a dramatic improvement over the use of the AWCI\/GA 214 standard. It is built to cater to IFRMs, including application variations such as orange peel. It also considers observer distance, which will be critical to identify when the use of the standard is appropriate. However, the use of this standard is problematic for several reasons.<\/p>\n

The AESS standard describes five specific levels of finish\u2014with each dramatically increasing in cost and the last one being a custom finish\u2014whereas TGD 16 outlines three levels. The first two levels line up well with Level 1 and Level 2 for AESS, but would leave Levels 3, 4, and custom all in extreme variation of the \u201cbespoke\u201d category.<\/p>\n

In AESS, the biggest increase according to the cost matrix comes between Levels 3 and 4; much more so than between Levels 1 and 2; and this would be equally the case when determining the variation between appearing smooth from less than 5 m (16 ft) away\u2014the only observer distance referenced in the decorative finish guidelines in TGD 16\u2014or being actually smooth, which is the expectation of AESS Level 4. These discrepancies in the finer points of the \u201cbespoke\u201d category would likely further lead to less predictability in estimating within this category.<\/p>\n

<\/p>\n

\"Table<\/a>
Table 1<\/b> The key characteristics of three intumescent fire-resistive material (IFRM) coating types.<\/span>Table courtesy The Sherwin-Williams Company. <\/em><\/span><\/figcaption><\/figure>\n

In addition, the description of a \u201cdecorative finish\u201d in the second paragraph of the ASFP guidance document is largely subjective and may lead to dispute on cost impact and remedial work to achieve a \u201cgood standard of cosmetic finish.\u201d The standard would also rely on the bespoke finish for all critical items in close view (AESS categories 3 and 4). Commercially, this is an issue for hard bid work, as the concept of a bespoke finish agreed in the field lends itself more to design build arrangements due to its inherent ambiguity. A contractor may have an issue providing an effective bid for an item for which its level of effort would likely be determined post-award.<\/p>\n

In the absence of an objective, industry-accepted standard, coatings manufacturers, applicators, architects, and building owners continue to struggle with all the basic characteristics\u2014material selection, application and finishing procedures, appearance standards, and more. Further, with no allegiance to a single standard, there remains considerable room for subjectivity, bias, and costly disagreement over the finish quality of coated AESS members. Ideally, an appearance standard for IFRM coatings would be built to align with the AISC\u2019s AESS categories and their specific surface quality requirements.<\/p>\n

IFRM materials, formulation, application, and finishing criteria<\/strong><\/p>\n

Any workable global IFRM finish standard for AESS must address the three generic types of IFRM coating materials: water-based acrylic, solvent-based acrylic, and plural-component intumescent materials. The comparisons found in Table 1 and 2 highlight key features of these material types and suggest how material capability, formulation, application, dry time, and service environment influence material selection and finish. In general:<\/p>\n