Analyze the thickness of waterproof membrane

In the two recent roofing forums, participants generally agreed that the roofing industry has matured. Emerging organizations such as RCI and SPRI have also been established for 25 years, while NRCA has been established for 124 years. These three organizations and other organizations have contributed to the progress and maturity of the roofing industry.

Although commercial roofing has become a mature industry, it does not mean that it will not stop there. Roofers increase their investment in new equipment, manufacturing equipment and production processes, and are constantly innovating. After examining the Shilai single-layer roofing material manufacturing plant, the author was impressed by the current production technology: computer-controlled recipe design, accurate weighing of materials, precise control of the line speed from the production line to the process temperature. Every manufacturer visited emphasized that the formula for each batch of coils was exactly the same, and each batch of finished products was subjected to laboratory tests to ensure that the standards were met.

The manufacturing process of single-layer coils seems to have matured. In the on-site spot inspection personnel report, surface defects, unevenness and other issues have rarely been involved, and the consistency of the color, texture, and surface of the coil has become the norm.

Since roofing coil manufacturing technology and process control capabilities have improved, why does the ASTM standard still allow single-layer coil manufacturers to produce 10% thinner coils than the standard required?

All four ASTM single-layer web standards were measured for thickness according to the ASTM D571 standard. In this standard, the coil thickness is taken as the average of the measured values at multiple locations. Only take a measurement of a certain part does not meet the test requirements.

Few reports said that the thickness of coils spotted on the construction site was 5% or 10% higher than the standard thickness. This shows that manufacturers have mastered the method of controlling the thickness of the coil.

This article investigated five single-layered coil manufacturers during the writing process. When asked whether the -10% thickness tolerance is needed from the production point of view, these five are not required; when asked whether the current production of the product will be thinner than the standard thickness of 5%, there is a saying that there are 4 It's highly likely, but it requires special ordering.

Manufacturers themselves admit that the current standard is wider than the manufacturer's own standards, so why should such a wide standard be set? All contacted manufacturers have indicated that they do not mind strict standards, and several manufacturers even revealed that they want the standards to be more stringent. Imagine if the standard shrinks the thickness tolerance to ± 5%, the result is that each type of coil will have the same thickness and will be thicker.

So, what is the effect of coil thickness on its performance? It seems that the thicker the coil, the stronger its puncture resistance, the better the wear resistance, weather resistance and aging resistance. From a certain point of view, increasing the thickness affects joint bonding, but experience has shown that a 2.4 mm thick coil (the thickest one) can also weld well.

If the ASTM standard tightens, the polymer layer above most coil reinforcements will be thicker. It contains many weather resistant components of the coil, such as UV stabilizers and heat stabilizers.

Of course, it's not hard to imagine that the manufacturer can increase the thickness of the coil by adding filler to the lower layer of the coil, and it has no effect on the long-term performance of the coil. It is preferable that all increased thicknesses are in the upper portion of the web, but it is also beneficial to add some thickness to the upper portion and the lower portion, respectively.

Does tightening the standard's thickness requirements have a negative impact? Increasing the thickness increases the cost, the coil thickness increases by 0.0254 mm, and the cost per m2 increases by 0.1 to 0.15 USD.

For a standard thickness of 1.5 mm, a maximum of US$0.5 per m2 is added for each 0.0762 mm increase in thickness. This increased cost is quite low compared to the full cost of installing the coil system. For manufacturers, tightening standards is generally beneficial because more stringent thickness requirements increase product production and transportation.

More than one surveyed company stated that due to competitive pressures, the thickness of roofing coils produced by its own company is at the lower limit specified by ASTM. Especially in the case of a sluggish market, if the product price of Factory A is 2 cents or 3 cents higher per m2 than Plant B, then Factory A is likely to lose orders. Therefore, few manufacturers will increase the coil thickness without considering economic factors. In the absence of a consistent standard, designers and end users will most likely approve 1.3 mm thick coils when the specified coil thickness is 1.5 mm.

Must this situation continue to exist? When the ASTM D08.18 non-asphalt organic roofing materials sub-committe revisited each single-layer web standard, the author of this article wishes to raise an objection to the regulations regarding the thickness tolerance of the web. These criteria should be reviewed every five years or when one member proposes a bill. The standards should reflect the possible situation in a reasonable and reasonable manner. As the manufacturing process improves, the standards should also reflect the improvement of product accuracy.

At the same time, designers can change the current status by specifying the minimum thickness instead of the standard thickness. Since manufacturers can and generally are willing to produce coils of the required thickness, the stricter tolerance of -5% seems to be a better temporary measure. Otherwise, the designer would be very annoying to explain to the customer that a 1 mm thick coil is no different from a 1.14 mm thick coil, and a 1.37 mm coil is no different from a 1.52 mm thick coil.

In the past 35 years, the relationship between the chemical formulation, manufacturing process and reasonable roofing system design of a single-layered coil and the long-term performance of the roofing system is much more important than the relationship between the thickness of a single coil and the long-term performance of the roofing system. However, if the problem of ensuring the quality of the coil has been solved, then it is absolutely right to produce a coil with tighter thickness tolerances.

The maturity of the product not only means that the use of a long time, but also means that the quality is stable and improve. Although the thickness of the coil is a trivial matter, it shows a positive change.