Although there may be a few products that require little thought in specifying, most require some minimum amount of research, comparison of similar products, and determination of the right combination of characteristics best suited to a project.
Even then, the process can be straightforward and fairly simple, provided the type of product is common, governed by widely accepted standards for materials and performance, well-described in product data, and supported by reputable manufacturers and representatives. Hollow metal doors and frames are a good example. Most manufacturers produce them according to one or both of two sets of common industry standards, published by the Steel Door Institute (SDI) and the National Association of Architectural Metal Manufacturers (NAAMM). Unfortunately, not all types of building products can be specified by use of similar standards.
Before you start that e-mail telling me how difficult it is to specify hollow metal doors,
let me add that the number of grades, types, options, and finishes requires the specifier to understand the hollow metal door and frame standards before making the several decisions needed to write the specifications. Each of the hollow metal standards organizations has described every component of hollow metal doors and frames, how they are fabricated and installed, and which models are suitable for a variety of applications. All of those things are well-defined in the standards, and most manufacturers indicate which doors and frames comply with which standards.
However, some products are far more difficult to specify than others, despite abundant and readily available information. One group that comes immediately to mind is coatings. Unlike hollow metal doors, coatings have little in the way of industry standards, and there are many ways of achieving the same result.
For example, say we want a waterproof coating for an indoor floor. A variety of basic chemistries are available - acrylic, epoxy, polyester, polyurethane, and perhaps others. Some of these are better than others depending on what they will be exposed to, and some are more decorative than others, but it’s likely that all would be acceptable if they need to contain only water.
Even if one type of chemistry rises to the top as being superior to the others, there may be countless varieties of that type. To add to the fun, manufacturers use different combinations of primer and top coats, have widely different test results for physical characteristics, sometimes use different test standards for the same characteristic, combine different types of chemistries in different ways, require different preparation, have different application rates, and specify different requirements for curing.
One manufacturer may claim you need 6,000 PSI compressive strength and 200% elongation, while another says you need 10,000 PSI and only 125%. One says you need a primer for a given situation, another says you don’t. One says you need to apply two topcoats, another says only one. One says you need a seal coat, another says you don’t. And so on.
All of them make logical arguments for their particular systems, and all can produce long lists of local applications. All of which makes it difficult to logically select a product to specify, and makes it equally as difficult to evaluate substitution requests.
Paints are almost as bad as floor coatings, but, because they will be repainted every few years, the performance characteristics are far less important. Otherwise, paints suffer from the same problem as floor coatings - few widely accepted standards.
I’d like to have a rational basis for making decisions about coating properties. By that, I mean a scientifically derived set of standards based on actual performance requirements. I’m fairly certain that the reason manufacturer A says you need 6,000 PSI tensile strength, and manufacturer B says you need 10,000 PSI, is that those are the values their products have. I have yet to see someone say, “Oak Ridge National Laboratory has determined that a floor coating system should have a minimum compressive strength of 4,792 PSI.”
Coatings aren’t the only problem; foam thermal insulation is another. We have specified extruded polystyrene with 25 PSI compressive strength for a long time, not because of any research, but because that’s what is required by ASTM C578 - and that is because that is what is produced and commonly used. Polyisocyanurate roofing insulation is available in 16, 20, and 25 PSI varieties. How do we compare the two types of insulation? If extruded polystyrene should be 25 PSI, should not polyisocyanurate also be 25 PSI? What is the rational basis for making this decision?
Going back to hollow metal doors, I doubt there is any research that tells us what the thickness of the face sheets should be, but in this case I don’t think it’s necessary. The gauges used probably are based on empirical evidence, but more important, one manufacturer isn’t trying to tell me that the face sheets should be one thing while the other manufacturers are saying something else.
It has been stated that industry standards such as those published by SDI and NAAMM are not sufficient, as they tend to reflect the lowest performance of the association members. Even if that is true, those standards still provide a valuable service by specifying a multitude of characteristics, allowing the specifier to use them as a base. After that, it is relatively easy to specify that a hinge reinforcement or some other component be something different from that required by the standard.
By setting standards, industry organizations serve a valuable purpose. While I encourage coating manufacturers, suppliers, and installers to cooperate in establishing standards for their industry, I also encourage the same for other products that suffer from missing standards. And if those standards are based on analysis rather than just a consensus of what is available, so much the better.
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