# Insulation in a hollow steel structural tube



## Simonsays (Aug 4, 2017)

Is there code language requiring placing insulation in a hollow steel structural tube in an exterior wall?  (There will be no reduction in thermal transfer as the heat will flow around the metal shell.)


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## steveray (Aug 4, 2017)

There is a requirement to have an envelope that meets code...I can't imagine that a hollow tube exposed on both sides would, but who knows...Prove it!


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## conarb (Aug 4, 2017)

Simonsays said:


> Is there code language requiring placing insulation in a hollow steel structural tube in an exterior wall?  (There will be no reduction in thermal transfer has the heat will flow around the metal shell.)


As a builder who has built several homes with red iron frames I can tell you that I want my steel to be heated by the heat in the house, otherwise condensation can develop on the steel creating damage to the sheetrock/plaster.  I had one inspector tell me that he had two homes in his jurisdiction that were "raining" inside from the condensation on the steel in the roof structure.


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## steveray (Aug 7, 2017)

Sounds intelligent to put the insul on the outside...


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## Pcinspector1 (Aug 7, 2017)

Not exactly sure if I understand your design but I would think that the steel tube would be cold in winter and hot in summer if not properly isolated. Vermiculite poured in the hollow steel tube comes to mine but it may have asbestos issues. Maybe another pour-able insulator could be used. I still believe your required to meet the building wall insulation requirement for your zone. 

Can the the steel be wrapped with insulation or is that already being proposed? Spray foam?


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## conarb (Aug 7, 2017)

Pcinspector1 said:


> Not exactly sure if I understand your design but I would think that the steel tube would be cold in winter and hot in summer if not properly isolated. Vermiculite poured in the hollow steel tube comes to mine but it may have asbestos issues. Maybe another pour-able insulator could be used. I still believe your required to meet the building wall insulation requirement for your zone.



It would take a massive change on the way steel structures are designed and fabricated, most columns are tubular and most beams are WF, the most targeted areas are the column to beam connections so there is no way to open them up to pour insulation into them.  The only way I can see to accomplish it would be to have the insulation installed in the fabrication shop after the steel is cut and before  the plates are welded in place, engineers require as much welding as possible to be done in the shop and not on site.



> Can the the steel be wrapped with insulation or is that already being proposed? Spray foam?



Smaller insulators don't want to touch jobs with steel, those who want to try to blow foam in cavities around the steel, on the other hand most failures occur in spray foam buildings, so it's touchy. On one house I had the inspector at frame inspection ask: "You aren't going to be using spray foam here are you?'  When I said no he just said good. Later I had a plasterer bidding the stucco and he saw steel in an overhang, he asked if there was spray foam in the house and when I said no he said: "Good, we have been named in two lawsuits on spray foam houses and our stucco had nothing to do with it."


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## Francis Vineyard (Aug 7, 2017)

Hear the choir: http://www.eng-tips.com/viewthread.cfm?qid=403784


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## conarb (Aug 7, 2017)

Francis Vineyard said:


> Hear the choir: http://www.eng-tips.com/viewthread.cfm?qid=403784


As a practical matter I remove the insulation on the inside of steel columns after insulation inspection and before sheetrock, even with inspectors I know who allow me to leave it out the damn insulators insist on putting it in saying it violates Title 24 to leave it out.


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## tmurray (Aug 8, 2017)

It is waste of both time and money to insulate inside a hollow steel tube. The conductivity of the steel will cause the heat flow to be around the outside. Without doing any calculations, I would guess that the payback period on the insulation would be longer than the anticipated lifespan of the building by a respectable margin. As others have stated, insulate on the outside.


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## north star (Aug 12, 2017)

*# = #*

Can anyone cite Code Sections to support their positions,
...one way or the other [ i.e. - is there specific code language
that requires hollow steel tubing to be thermally insulated,
either internally or externally ?  ]

Thanks !

*# = #*


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## Hamzah_12 (Apr 3, 2018)

I'm planning to increase the RValue in my exterior wall by filling the HSS with Spray foam insulation.  There is already insulation in this cavity.  1.5" to the HSS from the outside aluminum skin.


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## cda (Apr 3, 2018)

Welcome Hamzah !


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## tmurray (Apr 4, 2018)

You will likely not see any increase of Rvalue due to the high conductivity of the steel. If you want to increase the Rvalue in this are, you need to wrap the HSS.


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## JBI (Apr 4, 2018)

Agree with others, a waste of perfectly good insulation and money with no appreciable benefit. Continuous exterior insulation will provide the increased energy efficiency you are looking for without necessarily causing long term harm.


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## Robert (Apr 6, 2018)

I believe there is a requirement in the energy code (CA) for continuous exterior insulation for steel framed and studded buildings. We also needed it in addition to batt insulation in the stud bays to meet T24. Something tells me with the increasing energy requirements in CA, continuous exterior insulation will be required in wood framed buildings too...just a matter of time and what climate zone you are in.


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## Hamzah_12 (Sep 20, 2021)

I have an existing built up roof (institutional building) As we are placing a new roof platform and attaching this to the existing steel structure, then adding insulation to the exist gyprock sheathing with inuslation over.  AS these horizontal sections will be cut into the exising roof matierals to the existing steel roof, Can't we spray foam inside the HSS, and perhaps install insulation over.
My concerns are the new membrane to the existing / condenstion (sweating) over the longer term


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## Mark K (Sep 20, 2021)

Putting insulation on the inside of an HSS section is not feasible and would not be effective.  If one face of the tube is exposed to a cold temperature the heat on the inside of the building would flow through the steel in the tube bypassing any interior insulation..  Similar problem for light gage steel framing.

You need somebody who knows how to calculate the R value of the wall assembly with such a tube.  This typically means an architect or an HVAC mechanical engineer.


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## Hamzah_12 (Sep 22, 2021)

The spray foam insulation to be applied in this Hollow steel section will have a 2" layer of insulation applied over.  A neoprene pad will be installed between the new steel section and the existing steel structure.


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## Mark K (Sep 29, 2021)

I do not believe that attempts to place insulation between new and old steel will be effective.  What will matter most is insulation between the face of the wall and the steel in the wall.


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