As apartments and condos become more high-end, building acoustics and soundproofing become more important in homes or apartments as residents are not going are not going to tolerate hearing kids running back and forth or the scraping of furniture. In a healthcare setting, this type of noise impacts patient care and equipment effectiveness.
Understanding the ASTM E492 floor tapping test will help you engineer and build assemblies that meet building code requirements, sell for top dollar, and improve human well-being.
In this blog post, we’ll review what to expect during floor tapping machine testing following ASTM E492-22 standards, what building codes require, what occupants expect, and more.
What Is the Floor Tapping Test?
Also known as tap testing or the tapping test for flooring, the ASTM E492 floor tapping test measures impact sound transmission through floor-ceiling assemblies using a tapping machine. 
The sound levels of impact and vibrational transmission are measured in the lower room in ⅓ octave frequencies, which is translated into a rating known as Impact Insulation Class (IIC). Higher IIC numbers do a better job of reducing impact sound transmission, so it’s less likely occupants will hear sounds from the floor above.
Floor tapping machine testing determines the IIC of the entire assembly, not just a single product. By testing different combinations of framing and flooring materials, manufacturers, architects, and consultants can learn what most effectively addresses the types of sounds that are expected for a given end use. Completing the tap test for flooring helps professionals understand the impact sound that will be heard in the building and make adjustments to materials, placement, and construction to achieve the desired rating.
Understanding the Importance of Impact Sound Testing
Impact sound testing is required for multi-family dwellings, as well as certain types of commercial buildings, such as schools, hotels, and healthcare facilities. It’s one type of acoustical testing required by the International Building Code (IBC).
IBC Section 1206.3 requires assemblies to meet a minimum lab-tested IIC rating of 50 per ASTM E492. The International Code Council (ICC) recommends an IIC of 55 for “Acceptable” and an IIC of 60 for “Preferred” performance. However, it’s important to note that most occupants may find these IIC ratings to be unsatisfactory.
Today’s educated consumers expect multi-family dwellings and office buildings to have been designed and engineered with impact sound in mind. Noise at home and in the office has been proven to directly impact productivity, focus, and quality of life.
Researchers have found that noise annoyance is associated with depression and anxiety and significantly reduces human performance. A product and the systems it is used in must offer the desired performance or risk being substituted by designers and architects.
As you evaluate acoustic considerations in your project, you’ll also want to determine the sound transmission class (STC) ratings, which offer an indication of how soundproof a wall or floor-ceiling structure may be. The IBC requires a minimum STC rating as well, which has the same requirements as those for IIC. The IBC also requires a minimum lab-tested STC rating for assemblies. The minimum STC requirement is the same as that for IIC - 50 per ASTM E90.
ASTM E492 Test Procedure
The ASTM E492 impact sound conduction test is completed in an independent lab with two similarly sized rooms built on top of each other.
The flooring assembly being tested is inserted into a hole (testing aperture) in the floor of the top room. A five-hammer floor-tapping machine drops hammers one at a time, in quick succession with a microphone capturing the sound in the lower room.
The impact noise and vibration are generated at 16 standard frequencies between 100 Hz and 3150 Hz. The results from each tap are plotted on a graph and the final graph is compared to a standard reference curve to determine the IIC rating.
Since the test measures assemblies, a large space is required and very few testing facilities have the space to inventory a wide range of prefabricated 12x16 floor systems available. If you need the test completed quickly, you’ll want to choose an acoustical testing facility with as many prefabricated ceiling assemblies as possible.
Results and Interpretation
IIC numbers typically range between 25 and 85, with higher numbers offering better noise reduction. As mentioned earlier, anything below 60 may not be satisfactory for the occupants.
Some acoustical assemblies are naturally good at attenuating sound, while others require special detailing or accessories to make them work better.
There are five ways you can control impact sound:
- Source: Anticipate sound sources and design around them
- Mass: Increase the size of flooring pieces to absorb more sound
- Stiffness: Build in a way that materials can vibrate slightly to absorb sound
- Decoupling: Physically separate ceiling materials from the floor above
- Absorption: Add sound-absorbing materials to reduce sound
Many engineers and professionals will combine several of the controls above to create effective floor-ceiling assemblies for their projects.
For example, a concrete building offers very little sound control, so rubber or foam underlayment and a thick carpet or a rug with a high-quality pad would lessen impact sound transmission. When possible, increasing the distance between framing members or building a floating floor can also be very effective in attenuating impact sound.
How We Make Floor Tapping Machine Testing Easy
You don’t want to trust your large-scale building project to just anyone. NGC Testing Services has more than 55 years of experience conducting full-scale acoustical testing in one of North America’s most comprehensive and unique fully accredited, independent testing facilities.
Here’s why organizations of all sizes trust us for floor tapping testing:
- Quick Turnaround: A wide range of prefabricated 12x16 floor panels are in our facility and ready.
- Wide Range of Products: Multiple floor assemblies, including dozens of different wood and steel framed assemblies, and an overhead crane system that allows for efficient movement of those assemblies in and out of the test chambers.
- ASTM E492 Compliance: Facility built to maintain compliance with established test standards.
Contact NGC Testing Services to learn more about our acoustical testing services and how we can help ensure compliance and performance for your products or assemblies.