I'm interested in using insulated vinyl siding on a remodel project, more for the rigidity then the thermal value which is negligible. One of the major benefits of standard vinyl siding is the "built in" rainscreen. I'm concerned that insulated vinyl siding will not drain/dry well and the plywood sheathing will remain damp longer. Literature from Certainteed, Alside, and PlyGem all state that the EPS has a vapor permeance of 5 and that it's breathable. Is this a real concern? Are there any moisture horror stories with insulated vinyl?

  • Why not use housewrap (commonly known as Typar or Tyvek in these parts) to protect the sheathing? It protects against moisture from contacting the sheathing beneath, but is breathable from the inside to out in the event some moisture does somehow seep through. – stevieb Jan 19 at 18:13
  • I have the same siding what your gana put up and what stevieb mentioned is exactly how I had mine installed...good luck with your new siding – Joseph Wit Jan 19 at 22:52
  • House wrap like Tyvek is great and all but it can't do its job if the siding is flat against it. You're supposed to have a drainage plane (also known as a rainscreen) to act as a capillary break. – Bryanw511 Jan 20 at 19:37

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