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Fire + Sound Resistance

Quantifying the other benefits that come along with Masonry Construction

Masonry is well known for having outstanding fire resisting properties, as well as deflect and absorb sound waves. The end result is occupants who feel safe and comfortable. This page provides some of the background information and references behind the tabled results seen in the Simplified Partition Wall Calculator.

Where do these values come from?

Fire and sound can be tricky topics which is why CMDC is bringing as much useful information into a single resource as possible – part of our mission to enable the design community however we can.

Much of the source material used for the Simplified Partition Wall Calculator is taken straight from the National Building Code of Canada. Other industry material which also compiles similar information is linked to in the respective sections below (click to jump to fire ratings, and here to jump to STC ratings).

FRR: Fire Resistance Rating

Understanding the background of where fire ratings come from when it comes to evaluating masonry partition walls

The National Building Code of Canada 2015 defines the “fire-resistance rating” as “the time in minutes or hours that a material or assembly of materials will withstand the passage of flame and the transmission of heat when exposed to fire under specified conditions of test and performance criteria”. The fire-resistance rating of an assemblage may be determined by testing (CAN/ULC-S101) or on the basis of Appendix D.

The calculation method in Appendix D takes into account the “equivalent thickness” (amount of solid material in a masonry unit) and the type of concrete (Type S or N, Type L120S, Type L1, Type L220S, and Type L2) used in the manufacture of masonry units to determine the fire-resistance rating. The method also recognizes the introduction of material (mortar or grout) in the cells of the masonry units to influence the fire-resistance rating. This method is the most commonly used by designers to determine the fire-resistance rating of masonry assemblages (walls, partitions, and columns).

The presented FRR values in the results are based on an equivalent thickness that comes from an assumed percent solid based on what is most common across the country. When using the results for this table be sure to confirm with the unit manufacturer that the percent solid of their units is equal to or greater than what is presented in the results.

Table D-2.1.1. provides the values for the required minimum equivalent thickness for different values of fire-resistance ratings of masonry walls. Those ratings apply to either loadbearing or nonloadbearing walls and masonry walls in running bond or stack pattern.

To achieve a specific fire-resistance rating, concrete block manufacturers have the flexibility to fabricate units with a concrete type and solid content aligning with the prescribed minimum values required in Table D-2.1.1 or subject their units to testing in accordance with CAN/ULC-S101.

Additional information about the fire resistance of masonry can be found in the Canadian Concrete Masonry Producers’ Association (CCMPA) Metric Technical Manual – Section 5. Fire Properties and Design Details (here – opens in new tab).

STC: Sound Class Transmission

Understanding the background of where STC ratings come from when it comes to evaluating masonry partition walls

Airborne sound travels between adjacent spaces moving through separating wall, floor, and ceiling assemblies, as well as through the connections at the interfaces between these assemblies. In the context of masonry partition walls, the Sound Transmission Class (STC) rating provides an estimate of the wall’s acoustic performance in various typical airborne sound insulation applications. The higher the STC rating, the more effective the assembly is at shielding occupants from noise originating in neighboring spaces. Masonry walls are very effective sound transmission barriers, and they are commonly used to ensure desired levels of privacy and overall comfort in both living and working environments.

The National Building Code of Canada 2015 (Section 5.8.) indicates that ASTM E90 should be used as the standard test method to determine sound transmission loss of airborne noise through walls. The STC rating is directly related to the surface treatment, solid content, and density of masonry units. Overall, the cost-effective strategy for achieving an effective sound barrier commonly relies on the mass of the masonry. Denser concrete masonry walls have higher STC ratings.

Concrete masonry construction offers a wide range of STC ratings, depending on wall weight, wall construction and finishes. Additional information about the STC rating of masonry can be found in the Canadian Concrete Masonry Producers’ Association (CCMPA) Metric Technical Manual – Section 7. Sound Properties and Design Details (here – opens in new tab).

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