Commercial Estimators

I am curious to find out if anyone is using any so called "exotic" steel stud shapes for their wall framing in commercial buildings?

We are currently running into projects that are attempting to be sustainable and green and energy efficient. All admirable qualities however there are always issues  and unexpected difficulties that crop up. One of which is the thermal conductivity of steel studs. To meet the new energy codes requires that a continuous layer of rigid insulation be applied to the exterior of the steel stud framing. This then will be the thermal equivalent to a wood framed wall. There have been some tests done on several different configurations of steel studs that also meet or better the thermal values of wood framed walls without the exterior rigid insulation. Has anyone experienced these new stud configurations yet? Are they readily available?

I am just trying to stay ahead of the curve.

Thanks in advance

Bud

 There is an alternative to framing a wall and adding rigid insulation as a thermal break. A company called FoamBuilt www.foambuilt.com intergrates metal studs into rigid foam creating a prefab wall with continous thermal break and ready attachment for siding and interior finishes. I hope this helps.

Ah, yes, thank you for that information. I have visited their web site as well as some others that have the same type of system. After researching some more I have better defined my reason for wanting the information:

In our area (south central Pa) we are in a climate that creates a problem for designers. humidity in this area travels from the inside to the exterior in the winter and from the exterior to the interior in the summer. At least that is what I have been told. In commercial construction most of the walls that we build are metal stud either structural or non-structural infill. The thermal properties of metal studs is less than desirable and with the new emphasis on meeting the new energy efficiency this becomes a problem for the designers. I have found out that there are several metal stud configurations that use openings of different types and sizes in the webs of the steel studs. Bethlehem steel has slots in some that they ran test on and Marino has one with triangular openings. These are supposed to work by creating a longer path of thermal transfer throught the web and therefore improve the thermal performance of the wall system to near what a wood framed wall would be. The Oak Ridge National Laboratories have done "Hot Box" test on some of the configurations. To get the energy efficiency that the designers need, they want to install a 2" continuous rigid insulation on the exterior of the wall. This is often done using an EIFS system but there is hesitancy to using EIFS systems since there were water infiltration problems some years ago. So what they are left with is something that hangs on the outside of the framing but then creates a support nightmare through the 2" rigid insulation system since the rigid will not support weight of most materials. The best result would be if the "exotic" metal stud wall system would have the same thermal properties as the wood framed wall system which does not need a continuous rigid insulation on the exterior to meet the new efficiency requirerments. 

I understand that this is a long winded explanation and is not really related to estimating however I am hoping that someone beside myself is looking into this since it is going to become a larger problem when everyone  realizes what the new codes are going to require.

 Thank you for your patience in reading this long winded explaination.

 I suspect that soon somebody will come up with a form similar to the "thermally broken" shapes that are common in the glazing industry, although poured and debridged for structural metals seems a bit on the pricey side to become popular.

 It seems to me, however, that since any structure calls for sheathing over metal studs--wood or GWB, before any siding is attached, the thermal bridge is broken.

 I have seen details that call for felt where stud walls meet masonry walls to prevent condensation, but that's a separate issue.

 I don't see too much rigid insulation down South, it's pretty common up North, and the details pre-date any real concern about sustainability

 All comments are regarding commercial construction.

Bud,

I just sent you an e-mail.  We have a patented steel stud shape invented to address thermal bridging.  See our website, thermachannel.com.  We are not in production yet, but we can supply material for an order in normal industry time.  Of other possible solutions, we still don't see anything as viable as ThermaChannel.  I think it addresses most things in this thread.  I appreciate any comments.  Gavin

I received your information and I do appreciate it. I forwarded it to one of several Architects that I am working with in the area. I have been to the Oak Ridge site and read their information on the tests that they performed. If I was an engineer I could probably decipher and use some of the information that they provide. Most of the Architects (at least the ones that are honest with themselves) admit to being confused or at least concerned about the new standards and the ability to meet them economically. Two of the biggest hang ups for this are:

The thermal conductivity of the steel studs. How can the formulas be shown that indicate that a metal stud framed wall meets or exceeds the thermal value of a wood framed wall.

Condensation. How can the formulas for a steel framed wall assembly show that the dew point of the wall is outside of the steel framing member - in the continuous rigid insulation. Or is there a way to provide vapor barriers that accomplish the same thing.

This is all probably outside the scope of normal estimating however no one that I am dealing with seems to be asking the questions that will get to an answer.

Would it be of interest or benefit for any of the providers of the new steel stud shapes to develop these formulas and systems and then use them to provide an incentive for an Architect and owner to use the system with confidence?

Hello Bud,

Thanks for taking the time to read the Oak Ridge report.  That is pretty dense information.  How we break it down for architects is that the test showed up to a 16% improvement in r-value for that wall assembly by simply using our 1/2" deep stud design --and we would like to point out that we used high-performance framing of 24" oc framing, which has less steel in the wall overall.  By using standard 16" oc framing, there are more studs in the wall, more steel, and therefore more thermal bridging.  Our percentage of improvement over the standard stud would have been higher than 16% on a percentage basis had we framed at 16" oc.

So, the r-value of our 1/2" design, for that wall assembly, showed an r-value of 11.12, or a 16% improvement over that same assembly using standard studs.  So the effectiveness of ThermaChannel was demonstrated.  From there, there are many assemblies, and we could not possibly test them all at Oak Ridge.  You can read about this more easily in our short brochure on our website.

An industry standard for commercial walls, 6" deep, with 2" of exterior rigid insulation is r-14, I believe.  That is a calculated value, so if you actually tested that assembly, it might not even perform that well.  So, when we look at r-11.1 for our oak ridge results for the 1/2" deep ThermaChannel studs, with r-19 batt insulation and 1/2" gwb, that is an "actual" r-value, since it was tested.  Truly to compare the two, one would have to use the same method for both assemblies:  either use mathmatical calculations for both, or do actual hot-box test for both.

In short, our figures are always conservative.

We have had professional energy modelers take the information from Oak Ridge and calculate the building's performance.  For example, my partner and the inventor of ThermaChannel also works as an architect in a firm.  They designed a building using standard framing and batt insulation.  We asked the energy modelers to calculated the energy use/savings if the building were designed with ThermaChannel steel studs.  If it has employed our 1/2" deep flange stud, they concluded that that same building would have saved 3-4.7% of it's overall annual energy use.  A huge savings, with zero maintenance, over the life of that building.  3% was in Arizona (hot clime), 4.7% was in Minnesota (cold).  I'd like to point out as well, that that building was designed with 16" oc framing, while our data was calculated from 24" oc framing.  We need to recalculate the savings, using ThermaChannel data for 16" oc framing.  Something we are pursuing currently.  The results will be even higher energy savings.

ThermaChannel can still be combined with exterior rigid insulation for an even higher-performing wall assembly.  We just don't have the data yet to say exactly what that would be. 

In response to wood framing, we mainly look at steel framing for commercial construction.  At first we did not think we would have enough thermal benefit to compete with wood framing for low-rise residential construction, where wood is common.  However, we are starting to think that we will have enough.  Currently working with energy/mechanical engineers on this.

Condensation:  our designs lower the delta T (I hope I am speaking correctly, I am businessman versus an architect like my partner is), thereby evening out the temperature differential in the center of the cavity versus the wall or stud temperature.  This helps condensation issues.  It also greatly or completely reduces "ghost marking".  For those who don't know, ghost marking is where that temperature differential creates minor condensation on the wall surfaces which over time pic up dirt, striping the interior and exterior walls where the studs are.  In that case, it is mainly a cosmetic, maintenance issue.

Your last question, there are few new steel stud shapes.  Our is the only one that addresses thermal bridging at the flange or wall surface.  It is patented, so no one else can do this.  Others all cut out the web of the stud, which has other issues.  Yes, though, it would be of great value for providers of new studs, such as our company ThermaChannel, and others, to develop formulas and information for architects to making it easier to compare and specify with confidence new products of higher performance.  We are working on it.  (We are also seeking investment...)

Thank you again for your keen interest.  Please look at our brochure on our website, and e-mail or call me directly any time.  Contacts there.