Is it enough to shoot for code minimums? In today’s market, there isn’t much desire to spend money, since rental rates are down and condo prices are hammered. I’m often asked when an enhanced system is needed. In this writing, I’ll address what the market wants, verses what the market needs.
Over 40 years ago, ASTM developed a single-digit number that represented what a committee felt was relatively comfortable living for sound control. We shoot for a 50 for both STC and IIC performance in walls and floors today. This 50 doesn’t mean no noise; it doesn’t mean no complaints; it doesn’t mean that the project is designed with the right system. It is code compliance, and it is a broad evaluation of how well a wall or floor system does at filtering sound. It is over a broad frequency range from around 5000 Hz to as low as 100 Hz. We hear sound in a broader range than we evaluate. Overall, like most measurements, it is an incomplete method. Still, we have no better one today. Other parts of the world do different tests to measure noise, and for impact, there is a tire-drop test, a ball-drop test, and even a test in which individuals attempt to replicate the same walking noise in different buildings. I’m okay with the present ASTM method we use. I like that I can evaluate performance by understanding the curve. I think we need to better inform the market on what the results mean.
Flooring sound control works from the mid-range frequencies to the high, and is quite effective. It is much less effective at the low frequencies and when looking at a curve. The point at which impact noise drops is typically identified as the frequency in which a sound mat becomes effective. For a quarter-inch sound mat, that is typically around 400 Hz. For the MT version of KEENE’s QUIET QURL, the impact noise drops at a much lower 125 Hz.
People perceive high frequencies to be louder than low frequencies, and when we look at our standard, the filtering of high frequencies is considered more important. Our standard requires a much higher filtration at 3750 Hz than it does at 100 Hz. Where do our renters complain about noise? The answer is, at the lowest frequencies, where footfall noise is a big problem even in carpeted areas. It is the thump of the Jolly Green Giant in his bare feet. I describe it as a noise that you can feel as much as you can hear. The noise is below what we measure in the IIC standard. The component in the system that governs performance is the resilient channels.
With all of this information written out, do we still think that code compliance is enough? How do we do better, and at the same cost? Or, do we continue to accept simple code and design to the minimum?
When to shoot higher?
A general contractor asked me that question. The answer is:
1. For-sale construction – so, condominiums in all cases. This type of construction will have associations, and the litigation potential is great.
2. Any project that has the term “luxury.” This adjective has been evaluated by HUD to a performance standard greater than typical code levels of 50.
3. Any project in which the competition in the neighborhood has installed higher-than-code-compliant systems, and the local expectations are for a better product.
4. If the project might require a field test to gain an occupation permit; the cost of erring too close to simple code compliance greatly exceeds the extra cost for a higher-performing system.
At KEENE, we want to provide alternatives and cost-effective systems for building low-noise construction. We have ceiling products, wall products and floor products for all different levels of project needs. We design systems to individual project goals, and have a vast array of tests to draw from. Call us with your special case. We love a challenge!!
Sounds good, doesn’t it?