If they were going for a vapor barrier with that insulation, they failed pretty hardcore. Each edge of the foil would need sealing or the entire thing would need covered by a poly barrier.

I am not sold on the fact that the rafters and roof deck are cool enough to make condensate. What is the temp outside when this condensation occurs?

It would make more sense that there is a leak in the flat roof. Or an area that puddles and slowly leaks all the time.

I would say it is condensation. If it was a leak, you or the contractor would have seen the water stains on the ceiling. You have created a sauna. You need to vent the room to the outside. The rigid insulation used is not fire rated and should not be left exposed. If it was fire rated it would say on the foil facing.

Definitely condensation. The insulation is fire rated, you just can't see it because they flipped them upside down so you can't see the prints.

All in all, it seems like an airflow problem because I put a fan in there and haven't had any issues since.

Should the contractors have warned me of any of this or at least done a better job?

The fire rated side should be the side that is exposed. But unless you have a fire I would not worry about it. I would not blame your contractor for the condensation, he should have known, but what can you do...

this is what you have:

Polyisocyanurate also known as polyiso is seen in all kinds of
commercial building applications and more recently with residential
building projects. Polyiso is typically used with a foil facing and it
has an R value of 7.0 to 8.0 per inch of thickness. The reflective foil
facing makes it an excellent insulation board when radiant heat is
involved. The foil facing also makes it very easy to seal with good
quality foil faced tapes.

Cost = Polyiso is the most expensive of the foam board insulation products however it’s the highest R value.

Polyurethane
and polyisocyanurate are both closed-cell foams. They contain
low-conductivity gases in the cells (usually one of the HCFC or CFC
gases.) The higher R-Values (R 7.0 to 8.0) are the result of thermal
resistance of the gases in the cells. This can lead to a couple of
disadvantages including: off gassing of HCFC or CFC gases, and reduced R
Value over time as the gas escapes.

http://www.homeconstructionimprovement.com/foam-board-insulation-values/

as to fire resistance...I learned something!

Polyiso Maintains its High Level of Inherent Fire Resistance

All
construction materials, including foam plastics materials such as polyiso
insulation, must provide a suitable margin of fire safety. Among all foam
plastics, polyiso possesses the highest level of inherent fire resistance due
to its unique structure of strong isocyanurate chemical bonds. These bonds result in improved high
temperature resistance (up to 390oF, more than twice the temperature
resistance of other building insulation foams) which in turn leads to enhanced
fire resistance. In addition, because polyiso does not melt or drip when
exposed to flame but rather forms a protective surface char, its fire
resistance is further enhanced, especially in terms of flame spread and
flashover potential.
Polyiso passes both the ANSI UL 1256 and FM 4450
fire tests without a thermal barrier. Polyiso, a thermoset material, stays
intact during fire exposure in the ASTM E84 or "Tunnel Test.” It forms a
protective char layer and remains in place during the test, thereby meeting all
building code requirements and contributing to a fire-safe building.

http://www.polyiso.org/?page=FirePerformance

good links at this site too, for nerds like me who read technical sheets...

If your install were tight to the roof, and installed air tightly the

condensation issues would cease.

contractor should have done his research, or spoken to someone

who had experience with a successful install

best of luck

"I assume it's because the warm air inside is meeting the cold plywood of the roof therefore creating condensation."

That's pretty much it.

With the insulation not being air-sealed, it's likely that the warm humid air from the living space is getting above the insulation, condensing on the underside of the roof sheathing, then dripping down.

The insulation thickness and location should be confugured to prevent the sheathing surface from being a potential condensing surface.

Energy rater already wrote it, but I'll repeat, even though your roof is non-traditional being a converted space: For an unvented roof, the foam insulation should be tight to the underside of the roof sheathing.

A band-aid repair could be to use aluminum foil tape to seal the edges of the foil insulation and framing. Use the width of the aluminum tape to connect the foil surface of one polyiso panel to the foil surface of the adjacent polyiso panel, bridging over the exposed edge of the paint framing.

Depending on interior/exterior temperature differential and interior humidity levels, even after completely air-sealing the ceiling plane you could still get some condensation on the tape that is adhered to the wood ceiling framing due to thermal bridging.

"It is also un-ventilated without any central air and only a fireplace to heat it."

If the fireplace is an gas fireplace, those can be moisture-generating machines.

"The foil is facing the wrong direction"

Why is that cynthia designs?

In general, concrete remains porous and allows moisture to go through it for its entire life. In your case there was probably no vapor barrier under the concrete patio, so moisture is always slowly rising up from the ground through the concrete. You can control this somewhat with sealer and paint, but you should never install any floor covering that would be sensitive to moisture (like wall to wall carpeting). The floor will probably always be a moderate source of water vapor unless your ground moisture content is extremely low.

I can't see enough of the ceiling construction to know what to suggest. For example, is the plywood we see inside the cavity also the bottom of the roof deck, or is there a space above it?

Bruce

Any inspector would tag the addition. The poly board is not flame retardant, no matter what the contractor or energy-rater says, it is a dangerous hazard left exposed.