Three seasons

We are converting our screened-in porch (12x13ft on the existing 4' deep concrete slab) into a 3-season room (with insulated windows, 3'ft wall, and an insulated door.) The enclosed porch has a flat roof with deck (balcony) on top. 

We live in the extreme weather (heat/humid/ wind/ & cold) of Chicagoland. Hence, insulation and condensation are always our key concerns. As far as building experience, we are totally intimidated when dealing with exterior structure. What is the best way to insulate the enclosed porch and avoid mold problem in the future? Should we put a house wrap or foam sheaths on the exterior framing before putting on the insulation bat in between the wall cavities? We plan to use PT plywood (not siding) as the exterior wall though. Also, would the PT plywood being exterior wall whist having gypsum sheathing for interior wall appropriate for the circumstance? We haven't put much thought into the floor insulation just yet. Sigh. Thought an area rug will do for the time being. =P Thank you for reading and for your advice.

Anna,

Your questions would indicate that you may be biting off more than you can handle.  What you are asking pretty much covers the whole “building envelope” idea.  I do not know the exact building requirements in Chicago, so if I was you, I would find a reputable designer or supplier that could walk you through the insulation requirements.  I assume a 3 season room means you will not be using it in the winter months.  Does this mean you will not be heating the room?  If you are not heating it, then the insulation requirements really are not that important, since you are not using energy to heat and retain the heat in the room. 

In our area, Kansas City, the floor requires a R-19 (6”), and the ceiling requires a R-38 (11”) plus the ventilation area.  Check out a foam product called Icynene.  This product requires less thickness to deliver more R value and since it is closed cell, it does not require any air space.  Conventional insulation requires ventilation to minimize condensation. 

Un-insulated concrete slabs are very difficult to keep comfortable in cold climates, since concrete is a very conductor of heat and cold.  Have you considered a heated floor.  They make these types of rooms very toasty on those chilly days.  Here’s a link to a flooring company we use -  warmlyyours.com