Framing the sunroom - part 1 revisited.

I finally managed to add some sunroom details to the "details" section the other night so I thought it might be helpful to revisit "Framing the sunroom - part 1" and relate the new sketch to some of my earlier verbal descriptions.

Here are some of the points I wrote down in my earlier post along with some illustrations and a little commentary:

Since the sunroom is not to be conditioned space, the adjacent portion of the exterior wall of the house is treated the same way as it would be if there were no sunroom attached - insulation and housewrap to be applied before framing the sunroom against the house.

After insulating, the exterior wall of the house is covered with Typar before the remainder of the cladding system is installed.

To deal with the potential for a high R.H. environment in the sunroom, a high quality air barrier is required. In this case more "airtight sheathing" which will also function as the cladding for the exterior wall of the house. In addition, the portion of the "airtight sheathing" that functions as cladding for the exterior wall of the house is to be back-vented (like a rainscreen) with the gap coupled to the vented roof assembly of the sunroom.

The exterior wall of the house is clad in 1/2" plywood over furring strips. With the seams taped, the plywood acts as air barrier, vapour retarder and back-vented cladding for the exterior wall of the house. The red arrow indicates the path through which the "gap" is coupled to the vented roof assembly.

Since the roof over the sunroom also serves as a portion of the deck, it is by necessity very low slope (~1 1/4" over 14') - some minimal slope was provided to prevent water backing up against the house. The roof joist bays are to be ventilated to provide better drying potential.

a small piece was cut out of each shim at intervals to allow cross-ventilation between joist bays. Each cavity is vented to the exterior at the other end of the joist - detail not included in these drawings.

About As Helpful As You Can Be Without Being Any Help At All - Dan Mangan