Wall Assembly Selection
I am working on construction drawings for a speculative home I plan to build in Kansas City, Kansas (Climate Zone 4). It is a small (18′ x 34′) two story home with a simple pitched roof over a full basement. The wall assembly of most new construction around here is siding (this can be a variety of things from very inexpensive sheet goods to cementitious products, very rarely masonry) over building wrap over 7/16″ osb over 2×4 framing @ 16″ o.c.
I am looking at 2×6 framing @ 24″ o.c. (smart framing alone has been met with confused looks from local subs and suppliers). I am probably looking at cementitious lap siding for the skin. Zip sheathing is beginning to show up on job sites in the metro, I believe mostly due to the fact that the builder can avoid the building wrap. I am leaning to this product for the sheathing as it seems like it should provide a decent, somewhat idiot proof air sealing solution as well as structure and wrb. However, I have concerns about the longevity of the tape joints and the longevity of osb in general in this climate. I plan on blown in cellulose for cavity insulation.
I am concerned about condensation on the interior side of the sheathing and this assembly’s ability to dry properly (cementitious siding over Zip sheathing over 2×6 framing @ 24″ o.c. with blown in cellulose). In an ideal world I would like to add an inch of rigid insulation (possibly Zip’s R Sheathing) and a rain screen siding installation. However the cost of this system and the battle that will be fought to get it installed properly in this market is slowly pushing it out of the realm of possibility.
I suppose the gist of my question is whether the assembly I plan to use is ultimately going to produce a mold sandwich? After much research I feel (if it can adequately dry) that it may be the right balance of performance and economy in this market and climate at this time.
Any thoughts would be appreciated.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part