Moisture management for tiny house subfloor?
My husband and I are just about to start building a tiny house on a trailer in Nashville, TN, and I’d like to make sure our subfloor does a good job of protecting against moisture, as well as drying out when necessary. Any advice would be greatly appreciated!
Our current setup, from bottom to top, is:
– Steel trailer frame
– Metal flashing
– 2×4 framing filled with Roxul, anchored to steel flanges on the trailer using bolts
– 3/4″ Advantec with taped seams, which will connect to ZIP system sheathing as our air barrier
– Cork floating floor
I am wondering about a few changes to address potential moisture problems:
– Adding a layer of XPS just above the metal flashing, and below the 2×4 framing, to increase insulation and discourage water from moving up into the framing. I’ve run the numbers, and 25 psi compressive strength should more than handle the loads from the exterior walls. Does anyone see potential issues with adding XPS here?
– Adding a vapor barrier somewhere, perhaps directly above the XPS, as you would with underneath a concrete slab? Or will that cause negative consequences?
– Using a gasket or something else underneath the framing members to act as a capillary break (instead of a vapor barrier?).
I would really, really appreciate your advice! Thanks in advance!