Fire-Energy-Sound Calculator

Building codes and designers at times will specify minimum requirements for fire, energy, and sound. The building codes provide for these requirements to be determined by the calculated method as an alternative to actual physical testing of an assembly or utilization of a listing service to determine those properties. This Fire, Energy, and Sound Calculator assists in determining those requirements by calculated methods in accordance with the International Building Code and other referenced standards as outlined in various NCMA TEK. See Help File for various applicable TEK. Most producers that sponsor this calculator also sponsor e-TEK and e-Details on their web site, both of which provide information on code and detailing requirements to meet specified levels of performance. Note that calculated values tend to be more conservative than tested values. The purpose of the calculated method is for a matter of convenience and flexibility to allow determination of the literally infinite combinations of masonry unit and finish/filling of core options available. It is not intended for a calculated value to supersede a tested value if one is available.

Included in this calculator are 1) typical physical properties of common 4-inch through 16-inch (102-mm through 406-mm) masonry units, fill materials and finishes that are used to calculate the fire, energy and sound properties 2) in many cases physical properties of units in the sponsoring producer�s inventory are provided that will allow calculation of the fire, energy and sound properties of assemblies constructed with that particular unit and 3) allowance for customized units where the user enters the physical properties of a masonry unit that is not included in the tables of the calculator. When a specific typical or sponsor provided unit is selected, those properties cannot be modified (indicated as "grayed out"). In those cases when it is desired to enter the properties of a masonry unit, select "custom unit" and all of the physical properties of the unit must be entered.

When calculating the fire rating, a "Build a Wall" category is provided where the physical properties of the masonry unit, the nonfire and fire side finishes, the cavity or collar joint (if a multi-wythe wall is being considered) and the cell fill are considered. When these properties are entered, the information for the sound properties is available as well so those properties are included in the calculation in addition to the fire resistive properties. The energy properties have additional considerations and therefore that information is provided only in the energy calculation section.

Variables that affect the various property ratings for walls are as follows:

• 1. Fire ratings (see TEK 7-1C Resistance Ratings of Concrete Masonry Assemblies for more detailed information):

  • a. Equivalent thickness of the masonry unit: To increase the fire rating, increase the equivalent thickness of the unit which generally involves increasing the face shell thickness.

  • b. Aggregate type: Different classes of aggregates affect the fire rating. In the order of aggregate types listed, the lower the amount of equivalent thickness of masonry needed for a given fire rating. In general, lighter weight aggregates have better fire ratings for a given equivalent thickness

  • c. Unit filling: Filling the cells of masonry units with either grout or any of the materials listed under unit filling. Note that for using this option, all the cells of masonry units must be filled.

  • d. Finishes: Adding certain finishes (i.e. plaster and drywall) to the wall increases the fire rating. Note that for combustible type finishes such as drywall, better results are achieved by placing the finish on the nonfire side. However, the masonry must provide at least half of the total fire rating of the wall assembly and the finish on the fire side cannot be more than ½ of the rating of the masonry alone. In most cases fire rating must be determined by calculating the rating with the fire occurring first on one side and then the other. The lowest calculated fire rating obtained is the governing rating of wall.

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  2. Sound ratings:

  • a. Sound Transmission Class (STC) and Outside-Inside Transmission Class (OITC): See TEK 13-1B Sound Transmission Ratings for Concrete Masonry Walls and TEK 13-4 Outside-Inside Transmission Class of Concrete Masonry Walls for more information. This is a measure of the ability of a wall to reduce the amount of sound going through the wall. The higher the value, the more sound that is prevented from going through the wall. These values are a function of the weight (pounds per square foot) of the wall only. Anything done to increase the weight of the wall will increase the STC and OITC ratings. The weight of a wall section can be determined either through the "Build a Wall" component of the "Fire" calculator portion of this calculator or TEK 14-13B Concrete Masonry Wall Weights.

  • b. Noise Reduction Coefficient (NRC): This is an indication of a surface´s ability to minimize sound reflection within a room or in other words it is a measure of the ability to absorb incident sound. A value of 1 would mean that it can absorb 100% of incident sound. A value of 0.45 means that it will absorb 45% of incident sound. Generally, the more porous the surface, the higher the NRC rating. Unpainted, rough textured surfaces generally result in higher NRC values. The range of values considered by this calculator is 0 to 0.5. See TEK 13-1A Noise Control with Concrete Masonry for information on NRC.

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  3. Energy:

  • a. This section is completely independent of the other sections of this calculator and no information that is entered into the "Build a Wall" section is utilized in the energy calculation section of the software.

  • b. The energy calculations are in accordance with the prescriptive wall requirements of the International Energy Conservation Code, 2006 Edition (IECC-06) Section 501.1. This section also includes ASHRAE 90.1 prescriptive U- factors. Further guidance on the methodology used is found in TEK 6-1B R-Values of Multi-Wythe Concrete Masonry Walls, TEK 6-2B R-Values and U-Factors of Single Wythe Concrete Masonry Walls and TEK 6-12C International Energy Conservation Code and Concrete Masonry. Note that this software only returns wall sections that meet the prescriptive wall requirements of IECC-06. There are other tools available that allows compliance based on the building envelope as a whole rather than on the prescriptive component-by-component basis. This type of whole building envelope analysis is available in free software downloads off the internet such as COMcheck from www.energycodes.gov/comcheck/ez_download.stm for commercial buildings and REScheck from www.energycodes.gov/rescheck/download.stm for residential buildings. See TEK 6-4A Energy Code Compliance Using COMcheck for more information.