Condensation problem in shed

[Joelk]

I purchased a used 36' x 12' "Mini Barn" a couple years ago and store a couple cars in it through the PA winters. The PO installed insulation on the walls and ceiling. It has 2x4 walls and they installed R-13 foil faced fiberglass insulation which puts the insulation in direct contact with the roof sheathing. I am aware that there should be an air gap between the insulation and roof sheathing, but it was that way when I bought it.

I went into the building yesterday and the foil face on the insulation near the peak of the ceiling was damp, with some droplets of moisture present. The day started cool, about 40 degrees and it was very sunny. It warmed up to about 80 degrees outside. The building was much cooler inside than a similar building, except with no insulation, that is right beside it.

Other than removing the insulation, any suggestions on things I could do to reduce the amount of condensation?

 

[LS6 Tommy]

Vents?

Tommy

 

[Joelk]

Has screened vents approx 6" x 12", one at each end, about a foot below the peak.

 

[boobag]

ceiling fan to keep air moving?

 

[MagKarl]

Dirt floor?

 

[Joelk]

I don't currently have electricity to the shed so a fan is not an option, at least for now.

3/4" Plywood Floor.

 

[Alan Douglas]

If the surface is cooler than the dew point (which you can get from the National Weather Service page) you'll have condensation.

 

[jonjon1]

SO the vents are in the insulated space? I am trying to picture this, can you load some pics..

I would not have the insulation against the roof if that is how it is, simply pull the insulation down, and use fairing strips to make a false ceiling that is lower than the vents, if the vents are really low, put boxes on them and elbows in the fairing'ed space. Then reinsulate and seal the space below the fairings, I will try to take a picture of how I did mine, next time I go there.
I insulated the shed I did this too with a single piece of HUGE insulation from another metal building we put up, so I literally cut a 9ftx16ft piece of r30 and layed it up there over the fairings, but my vents were in the middle of the insulation so I made a sheet metal box that angled them up above the insulation so they were venting the "attic" space and not my insulated space. I did have a bit of moisture on them sheet metal boxes, but I insulated them and never seen it again...

 

[Boyd]

Two 6"x12" vents for an insulated building that size isn't nearly enough. Get that insulation away from the roof decking and add a couple of whirlybirds.

 

[CNGsaves]

With no electricity, you'll have to improvise McGyver solution like solar powered vent. Heck, could have whirly bird vent on top driven by wind.

Experiment with couple low cost ideas and see if any help.