What is 703 and Why Don’t I Need It

[AVare]

703 is the commonly used term for acoustic absorbent material. It is formally the registered trademark of Owens-Corning for OC’s 3 pound per cubic foot fiberglass. There is nothing unique to 703. You can use any company’s product. At some places mineral wool is cheaper or available. With mineral wool, the 4 pound per cubic foot material is acoustically equivalent for our work.

In my part of world, 4” 703 is $3.80 per square foot . Roxul Safe n Sound (2.5 pounds per square foot and 3.5” thick) is 27 cents per square foot. A little off on the density but ONE FIFTEENTH the price!

An interesting effect of the pricing is that gapping becomes a non issue. People at times consider having an air gap between the material to increase low frequency absorption. If a gap is used, their has to be some way to keep the material from falling into the gap. Typically this done with chicken fencing and strapping to which it is attached. The chicken fencing costs 50 cents per square foot here. Putting a 3.5” gap behind the Safe N Sound would be over twice as expensive as filling the entire space!

Andre

[Ethan Winer]

All good points Andre.

[gullfo]

yeah i tend to use the word "703" to mean "a rigid fiberglass/mineral/rock wool product with a density of 3lb/cu ft" since its much shorter to write in design specs i typically do search-and-replace so people realize there are options by using alternative products such as recycled cotton batts.

[xSpace]

Like when a co-worker says he'll get his "skill saw" and I see he has a Makita.

I says to him, I says, "that ain't no skil saw ya bone head, that's a Makita circular saw.

To which he replies, "yea, I know, it's a Makita skillsaw."

You will usually find me at careerbuilder.com not long after that!

[SharpNine]

I just love my DeWALT sawzall.

[gullfo]

we should Xerox this thread...

[Ethan Winer]

we should Xerox this thread...

Or at least put a Band-aid on it and damp the remaining blood with Kleenex.

[AVare]

A post on another board prompted me to do some price and thinking.


OFI-48 (Ottawa Fibre's equivalent to 703) in 4" thickness is $2.00/ft^2.

Safe'n'Sound is $0.53/ft^2

So right now Safe'n'Sound is one quarter the price of an "off brand" 703.

It is now the same price to use 2 layers of Safe'n'Sound as it is to gap single layer with the gap equal to the thickness of the material.

This provides a certain trend in bang for the buck with readily available materials. 3.5" costs as much as 7" gapped. Looking at at the products and thinking deeper, I wondered about the next step in the progression (going 3.5", 7" then 10.5") R14 is $0.53/ft^2 and R22 is $0.68/ft^2. A 10" deep absorber made with R14 and R22 costs $1.23/ft/^2.

Putting all this in perspective, knowledgeable research can save significant amounts of money compared to using 703 and it's equivalent.

Economically,
Andre

[AM-1]

Which will be the best for my DIY bass traps? Roxul 15, 60, or 80?

I am figuring on making between a 6", 8", 10" or 12" deep bass trap. Am I to assume that the 12" would be better without argument or just more expensive and not as much return?

Thanks