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Does anyone have any advice on insulating a glassed-in 3 season porch for winter use? The floor is my major concern: There’s a nice finished floor on top so I’d like to insulate it from below with batt insulation but I’m not sure how to enclose the cavity. I was thinking of Tyvek and/or 1/2″ plywood however there’s less than 18″ from the ground to the bottom of the joist which would make installation very difficult. Any suggestions?
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Would you have an objection to rigid foam? It provides a higher R-value per inch than fiberglass and would be less likely to be affected by moisture or pests.
Have you any thoughts on how this porch is to be heated? In some locals, if you tie in to the home's HVAC forced air system, you now have an addition, not a porch, and the codes change for it.
*TuckerYour method of insulating the floor will not yield ai warm floor! While opinions will vary, I've achieved excellent results in similar circumstances by building and insulating perimeter walls down to below grade with 2" XPS (expanded polystyrene-R5/"). Unless your grade level is rock, it's not really terribly difficult to dig a shallow trench (1 foot minimum depth)and to frame enough support to hang plywood on and sheath the inside with the styro right up into the floor joist cavities. Don't forget to carefully cover the dirt floor with 6mil poly or equivalent. And don't vent the space!! If you want to take it to the next level,i hang sufficient baseboard heat down there with it's own stat. set at around 50F.-pm
*... if it's an "addition," they'll likely reassess the property for taxes, too ... They tried to with us, but I said NO, 3-season! No heat!Patrick sounds on track. But I insulated the exposed underside of an existing small addition to our kitchen with 2-4" of XPS (thickest around the plumbing), plus blew cellulose into the 2x6 joists, and the floor feels fine to bare feet in winter (except the patch i haven't finished yet). Of course, this is just wimpy VA.
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Does anyone have any advice on insulating a glassed-in 3 season porch for winter use? The floor is my major concern: There's a nice finished floor on top so I'd like to insulate it from below with batt insulation but I'm not sure how to enclose the cavity. I was thinking of Tyvek and/or 1/2" plywood however there's less than 18" from the ground to the bottom of the joist which would make installation very difficult. Any suggestions?