Storefront Vestibule & Tube Steel Frame Insulation requirements

[QuestionThat]

Wood framed Commercial building. Only steel is at a vestibule that has a vaulted single story space primarily as an architectural feature. 16" deep tube steel beams with 6" tube columns used to create a frame that has been designed to support aluminum storefront rather than using a curtain wall system. Storefront meets energy code requirements but not sure how to handle the tube beams and columns. None of the exterior walls have insulation..... all glazing.

Does anyone have a good handle on whether the tubes need to be wrapped in insulation as far as energy code requirements are concerned?

Drawings have currently been detailed with 2" rigid on exterior face of beams and columns and 1/2 insulation on interior with all wrapped in brake metal.

Original reason for adding insulation was primarily because of concern with condensation at interior.
Now I'm rethinking this as a requirement.... Subs indicating that they run storefront all day long on top of painted tube steel with no condensation issues. Even go so far as to say that the insulation actually creates condensation problems (between the insulation and brake metal that stays in the system).

Curious as to everyone's thoughts... number one if a requirement per IECC and number 2 if better to install or leave out for purposes of eliminating/ reducing condensation.

 

[steveray]

Is the vestibule conditioned? I think I would treat it as a glazing assembly and meet the overall U factor and move on....

 

[QuestionThat]

Yes it's conditioned. Thanks for your input/ insight. Any one else like to chime in? Also interested in thoughts related to not insulating and condensation at the steel.

 

[tmurray]

We insulate steel on the outside here due to condensation, but I'm in Canada, so your climactic conditions are likely different.

The foam is not causing condensation. It is changing where the condensation forms. Adding the foam is moving it to a place people can see as opposed to a place they can't see, or don't care about.

There is no way to eliminate condensation. It is simply a function of warm moist air cooling to a point where it must shed moisture. Adding, subtracting, or moving insulation around in the assembly just controls where the condensation will form. Best you can do is make it so most of the time the condensation would be forming in a closed cell foam layer that won't allow it to form due to the material properties.

 

[Paul Sweet]

Exposed steel framing shouldn't be a condensation problem if it's inside the conditioned space. Just make sure the A/C system isn't directing cold air at it.

 

[QuestionThat]

TMurray- So if the dew point temperature point is contained within the rigid insulation then it won't condense.... correct?

Everyone. Hate to admit it but I really don't have a good handle on this. Looking into dew point calculations to try and get my head wrapped around how all this works together though. Never done them before. Any insight?
For starters wondering if in the south east (South Carolina, Greenville area) need to do winter or summer exterior/ interior air film calculations. Quickly thinking this through the steel has no R value so it just becomes whether or not the temperature differential and how much moisture is in the air (interior in the south with AC?) and whether or not the steel gets cold enough to become a condensing surface.... correct?
After it's all said and done if I wouldn't be concerned about a non thermally broken aluminum storefront frame having condensation issues, then I shouldn't have any concerns about exposed tube steel condensing either..... correct? So, with my conditions should I have condensation concerns.... say on storefront? For the record we are using thermally broken storefront, just thinking through this with non thermally broken.

Also. Any suggestions as to where I can get the various charts and formulas needed to do the dew point calculations?
Thanks for any help you can offer as I would really like to understand this.

 

[ADAguy]

Consider that being where you are the seasonal temp extremes will also lead to the potential for condensation.
Do you face south (shaded/unshaded) or north as time of day will also add to your considerations.
Lastly how large an area is the storefront? As a % of the overall exterior?