Aluminum Wall Framing

[brzilian]

Does anybody have sources for aluminum extrusions used for framing walls? How does it compare to framing walls with regular wood 2x4's? Does it make a difference as far as cost and soundproofing qualities?

Thanks in advance.

[RICK FITZPATRICK]

Hello brzilian. I'm not completely sure, but as far as "I" know, ALUMINUM extrusions are not used as framing because of fire. Steel IS used for forming studs and plates(channels). However, aluminum IS used for external framing such as glass store fronts, and exposed framing such as CURTAIN WALLS on commercial buildings, and even siding in some respects. But as far aluminum used as framing for drywall applications, I would say it isn't available, but I would be enlightened if it was. As usual, its only my .02
fitZ

[brzilian]

Maybe I have mispoken then.

The reason I ask is that I recall one business I worked for in the past using this type of product to quickly frame in office space inside a large warehouse facility. This took place in New York State if that makes a difference to anyone.

Based on the weight and appearance of the material, I thought it to be aluminum.

[Innovations]

No, it was most likely steel. While aluminum could be hardened enough to do the job the melting point is too low.

[knightfly]

One probable reason what you saw looked like aluminum would be a smooth galvanized finish; this can look a lot like aluminum. The reason it seemed light may be that it was an interior, NON-load-bearing partition; these can be built using lighter gauge steel studs, typically 25 gauge instead of the 20 gauge that must be used for structural partitions. that thin a metal would seem light just from the degree of thickness.

Even steel doesn't have a high enough melting point for SOME fires, witness the results of 9/11 - but it's approximately 3 TIMES the melting point of aluminum, and the SpG's of the two are also nearly 3:1.

As to sound control, the heavier, structural grade 20 gauge steel studs are almost imperceptible from wood because they are relativey stiff; the lighter, 25 gauge NON-structural (as in, non load-bearing) studs are flexible enough to partially decouple the two wall surfaces, so have nearly identical properties as wood studs with Resilient Channel added; for interior, non load-bearing studio walls, this is probably the least expensive FAIRLY good way to build.

One other consideration, though, is moisture - especially if your climate is humid at all.

From Building Sciences Corp (an absolute goldmine of useful building info) -

"Metal Studs This type of stud is 300 times more conductive than wood studs. They are prone to condensation and ghosting. Metal studs should never be used with cavity insulation because it makes them even colder. If metal studs are used they should be limited to interior walls or to the interior of rigid insulation assemblies. Metal studs should never be used below grade unless they are separated from slabs with thermal breaks (“sill gasket”) and separated from foundation perimeter with rigid insulation."

Link to the entire document -

http://www.buildingscience.com/resou...r_Renovate.pdf

Note that anywhere it's recommended to use rigid insulation with steel studs, you simply should NOT USE them at all when building sound proof walls. This is something I just learned, and need to "burn in"...

HTH... Steve

[brzilian]

Lots of good info Steve! Thanks!