Residing for wildfire
I’m trying to decide between Hardie plank Board and batten and corrugated vertical steel siding on the gable end of my two story house. Colorado climate zone 5.
the wall faces West and gets brutal sun in the afternoon. The wall is 5/8″ Sheetrock, poly vapor barrier, 2″x 4″ 16″ o.c. 7/16″ zip sheathing.
Steel gets literally hot enough to cook on here but would cool relatively quickly especially with a rain-screen gap.
Fiber cement doesn’t seem to conduct nearly as well but has much more mass and I assume would hold the solar gain much longer transmitting it into the building for longer once the sun goes down.
Just for the inside of that wall, is either a better choice than the other in terms of transmitting heat to the inside?
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Replies
You've kind of answered your own question; the steel will get hotter but cool down quicker. The fiber cement will hold heat, but only a little longer. There is some mass, but not a lot. If you have a vented rainscreen between the cladding and wall framing assembly, the heat transfer from the cladding to the wood will mostly be radiative, with some convective transfer through the material that makes up the rain screen. The whole assembly will act like an attic that is insulated at the attic floor. With the wall only being a 2x4 and no continuous insulation, the heat will pass through easily unless there is a lot of air movement through the rainscreen (windy day). Good for the winter, not so good for the summer. CI will help a lot, choosing a lighter color for the cladding color will help some.
Thanks for the reply. I know an insulation break on the outside is the real answer. just wrestling with "mission creep"