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moment frame thermal break

go do it

I thought this was covered once but a search bared no fruit.

Is there a way to achieve a 100% thermal break at a moment frame / clerestory windows and other store front assembles?

Other than wrapping the tube steel with foam and or burring it in framing which is not called for how can a thermal break be achieved and have exposed TS on the interior? This is in a hot arid climate.

Thanks

 
Jan 5, 20 7:46 pm
Wood Guy

I'm not sure what "exposed TS" is. This may sound simplistic, but to create a thermal break, you need an insulating material between the steel and the outdoors. There is not a specific R-value or thickness of insulation required to meet the definition of the thermal break; in a hot climate just R-5 or R-10 would probably be enough. 

Jan 6, 20 9:48 am  · 
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Exposed TS = exposed tube steel?

Jan 6, 20 11:47 am  · 
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Wood Guy

Doh, of course, thanks. That leads to my tube steel rant--of course architects prefer its clean look to that of W section or other most industrial-looking shapes. But tube steel is usually produced using basic oxygen furnaces, which run on coal and are heavy polluters and greenhouse gas producers. W-sections and similar shapes in the US are usually made using electric arc furnaces, which run on electricity and produce steel products with much less upfront carbon emissions. Plus tube steel is not an efficient use of material, compared to wide-flange shapes which place material where it will do the most good.

Jan 6, 20 12:28 pm  · 
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Non Sequitur

^ I prefer W and C sections over HSS. Do I get a cookie?

Jan 6, 20 12:36 pm  · 
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Wood Guy

You're unusual among architects, NS. You get a cookie.

Jan 6, 20 1:51 pm  · 
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OddArchitect

Make sure it's a Canadian cookie though.

Jan 6, 20 1:58 pm  · 
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Non Sequitur

Maple flavoured.

Jan 6, 20 2:00 pm  · 
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Non Sequitur

At first, I thought this was another Jawknee post... but then I realized that all the words in the title were english and made decent sense.

Hot & Arid is 100% not my climate, but we have had to deal with thermal bridging in large structural members before (2' to 3' perimeter HSS members).  I find it rather impossible to split the structural member to add a thermal break, but our solution was to fill the steel tubes with spray-foam for a considerable length beyond where a TB would be placed.  The steel will sweat tho...

Jan 6, 20 10:00 am  · 
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Wood Guy

The foam fill is probably more to avoid internal condensation than to provide energy efficiency, right? At R-0.003 (U-322), A992 steel is about 400 times more conductive of heat than framing lumber (R-1.2, U-0.8). It takes 33 feet of steel to equal the thermal resistance in one inch of wood. Or 160 feet to equal an inch of foam.

Jan 6, 20 10:50 am  · 
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Non Sequitur

^correct, we had many issues with steel sweating since we work with -40C to +40C temperatures. Depending on OP's design, a hunk of nice finished lumber might be OK. You don't typically see TB in timber framing.

Jan 6, 20 10:57 am  · 
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NS, do you have access to Tnemec's Aerolon up in the great white north? We've had some good success using it to help prevent the sweating you're talking about. It's not appropriate for every situation, but might help in some of them. Don't believe the marketing hype though, it's not a thermal break. It's simply an insulating coating.

Jan 6, 20 11:20 am  · 
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Non Sequitur

Yeah, I would not believe a TB can be achieved with a film. Product looks interesting but I don't think it passes all of our ULC regulations since I can't find much about it, but it passes our fire reqs, so it's probably out here.

Jan 6, 20 11:46 am  · 
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It is fun watching the Tnemec representatives' gears churning when I've questioned them on why they call this a thermal break (heat is still transferring through the steel unabated). I only use it when I'm trying to keep the surface temp from dropping below the interior dew point to prevent condensation on the steel. For that, I think it is a remarkable product.

Jan 6, 20 1:15 pm  · 
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It's a full custom build with armatherm or some other break material.

Jan 6, 20 10:57 am  · 
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OddArchitect

It's like Miles said, you have to crate two separate pieces of your steel frame and use a thermal brake product.   

We've used this product in western Colorado (temp range 5F to 110F) with great success. It's a structural plastic.   

Fabreeka.

https://www.fabreeka.com/products/#category-48

Jan 6, 20 11:07 am  · 
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Non Sequitur

Neat product. Never seen this before but it looks like it was just recently approved in Canada (august 2019).

Jan 6, 20 11:16 am  · 
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OddArchitect

Yeah the stuff is rather cool - structural thermal brake plastic! I'm such a geeky dork to be excited about this.

Jan 6, 20 11:42 am  · 
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We've used Fabreeka's product in the past. I recently came across the Armatherm products Miles mentioned and I'm waiting for the next opportunity to discuss with a project's structural engineer to see if they have a preference for one or the other. They both look comparable from my cursory glance.

Jan 6, 20 11:50 am  · 
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OddArchitect

Good to know. Thanks EA!

Jan 6, 20 12:19 pm  · 
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atelier nobody

Used it under every column baseplate on a project in Antarctica, as well as vertically separating steel frame from exterior wall and roof assemblies. Somewhat creatively, also put it under door thresholds to prevent bridging from exterior to interior concrete.

Jan 6, 20 3:18 pm  · 
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t a z

Generic details and (at the end) more products: 

https://www.aisc.org/globalassets/modern-steel/archives/2018/09/breakingupisnthardtodo.pdf

Jan 6, 20 6:36 pm  · 
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^ Good article. Saved for later.

Jan 6, 20 6:58 pm  · 
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proto

learned new stuff, thx peeps

Jan 6, 20 3:45 pm  · 
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