Pole barn insulation/ventilation question

[Bill Anglin]

Hi all,
I have a question regarding insulation and ventilation in a pole barn. The barn was constructed without a ceiling. Insulation and full continuous vapor barrier is installed at the roof sheathing. A ceiling was installed at a later time. No vents are installed at the soffits, roof or gable. The barn is heated. Typically you would insulate the ceiling here and not the roof sheathing and then ventilate the attic space. Will this be a problem? Would any of you recommend a correction here? Thanks for the help.

[Raymond Wand]

Looks fine to me, don't see any moisture issues on the framing. And the vapour barrier/insulation is added the way it was simply because there was no ceiling initially.

[Bill Anglin]

Thanks for your feedback. There was no evidence of failure with the system. I guess what I'm wondering is, if you install a ceiling then should you remove the insulation from the roof sheathing and install insulation at the ceiling? Then add vents to ventilate the attic space? If you seen insulation on the roof sheathing of a house(in an attic space), you would certainly write that up as needing correction right? How/why is it different in a pole barn with a heating system?

[John Kogel]

I think the attic is like the second storey with a vaulted ceiling. It is part of the heated space. The air spaces above the roof insulation should be ventilated at least a bit, I think. Metal roof?

Sure, they could improve what's there, but maybe it's working fine as is. If the heat warms the metal of the roof, they won't get a lot of condensation. But if there's ice on the metal and a lot of moisture inside, it could become a mold farm.

[Raymond Wand]

Insulating the underside of the roof is no different then spray foaming the underside in which case ventilation would not be required.

Yes you could relocate the insulation from the underside to the ceiling but I don't see any benefit.

[Raymond Wand]

Here is some further info, although its for a house it applies to your query.

BSD-149: Unvented Roof Assemblies for All Climates — Building Science Information (http://www.buildingscience.com/documents/digests/bsd-149-unvented-roof-assemblies-for-all-climates?searchterm=attic+insulation)

[Garry Sorrells]

With a contractor hat on, add gable end vents. Blow insulation onto ceiling. Call it macaroni.

As the building (barn) is presented there is a possibility for condensation to develop.