Steel Building Insulation

[hidollartoys]

Just completed an all steel (structural and skin) building. There is the usual fiberglass blanket insulation sandwiched between the skin and perlins/girts with a vinyl vapor barrier on the inside. This only provides an advertised R-10. Since I am heating with radiant in floor system, I would like to add additional insulation.

My question is.... Since the vapor barrier is present, Do I use faced or unfaced batts?

 

[Wastedwagesracing]

I have asked this same question on my behalf. Sounds like you need to open up the vapor barrier you already have. You can slice it open or remove sections of it. Then your additional insulation needs to have a vapor barrier on the side facing the inside of your building. But lets see if that is still the opinion of the group now.

 

[Charles (in GA)]

You do not want to go cutting the backing on the existing insulation. It will begin to fall apart very quickly. Are you going to build stud walls inside the steel wall? How do you plan on mounting additional insulation?

Charles

 

[hidollartoys]

The steel girts (walls) are 3 5/8" wide (deep) on 24" horizontal spacing. The plan is to run the 24"+/- insulation horizontal in the spaces. The perlins (roof) are 6' wide, also on 24" spacing so I will be able to do the same with higher Rfactor insulation. The girts and perlins are formed "C" channels so the wall and ceiling interior panels (steel on ceiling and walls) will be screwed directly to the girts/perlins sandwiching the insulation between the interior steel panels and the outside insulation blanket.

 

[Charles (in GA)]

Use the double sided sticky tape that is used to stick the insulation in place before the sheet goes up, and run it on the flanges of the wall girts, stick the flaps of the kraft backed insulation rolls to it, and install the interior wall sheeting over it. I don't see an issue and would not worry about the first layer of insulation being a problem.

Charles

 

[Highbeam]

The first layer of insulation is not the problem, it is the vapor barrier. If you have both interior and exterior vapor barriers then water will be trapped within. Not sure how it would get there in the first place.