California's CALGreen Code Hot Topic- Sound Insulation

If you're an architect, designer, builder or code official in California that has to comply with the CALGreen code, watch out for this requirement. It's getting missed most of the time during the plan review process on new projects.

Wall and roof-ceiling assemblies making up the building envelope shall have a minimum sound rating STC of 50 and the exterior windows shall have a minimum STC of 30 per CALGreen 5.507.4.1 when any of the following apply:

1. The building is within 1,000 feet of right of ways of freeways (think of all the minimarts, restaurants and commercial/industrial buildings that fall within that ROW of freeways)
2. The building is within 5 miles of airports serving more than 10,000 commercial jets per year
3. Where sound levels at the property line regularly exceed 65 decibels, other than occasional sound (train horns, emergency vehicles, etc.).
Original Post
Another point of contention that arises regarding this issue is where and how to measure the distance between the building under question and the ROW of the freeway.

In our office, we use Google Earth along with the Ruler function to estimate the distance in feet between the building and the freeway.

But where to measure from- edge of building to edge of freeway, to centerline, where is the ROW, etc, etc.

As you can imagine, providing sound transmission (STC) for the building envelope walls and roof-ceiling assemblies is challenging to design at time (think metal buildings, etc) and adds to the construction cost.

Designers and builders/owners are already fighting almost every call regarding this requirement.

So, figure out in advance how you will address this topic before it becomes a hot issue and a struggle with each project proposed near a freeway.
CALGreen Section 5.507.4.1 exception #1 mentions "freeway". CALGreen does not define the word "freeways".

As such, a determination would have to be made if it's a Highway vs a Freeways vs ? OR, is it CALGreen's intent to equate Highways and Freeways?

For example, California's Highway 99 that runs through the Central Valley is a "Highway" and NOT a Freeway.

So for the purposes of CALGreen, if a building is within 1000 ft of Highway 99, does Section 5.5.7.4.1 apply or not?
Good question.

From http://www.merriam-webster.com/dictionary :

Definition of FREEWAY
1: an expressway with fully controlled access
2: a toll-free highway

Definition of HIGHWAY
: a public way; especially : a main direct road

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From CALGreen:

5.507.4.1 Exterior noise transmission. Wall and roof-ceiling assemblies making up the building envelope shall have an STC of at least 50, and exterior windows shall have a minimum STC of 30 for any of the following building locations:
1. Within 1,000 ft (300 m) of right of ways of freeways.
2. Within 5 mi. (8 km) of airports serving more than 10,000 commercial jets per year.
3. Where sound levels at the property line regularly exceed 65 decibels, other than occasional sound due to church bells, train horns, emergency vehicles and public warning systems.

Exception: Buildings with few or no occupants and where occupants are not likely to be affected by exterior noise, as determined by the enforcement authority, such as factories, stadiums, storage, enclosed parking structures and utility buildings.

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Does "highway" 99 fall under the freeway definition? It seems that the noise level may exceed 65 decibels if a project is close to a highway or freeway, so #3 above may apply. Here's traffic noise information from US Dept. of Transportation:
http://www.fhwa.dot.gov/environment/htnoise.htm

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