Insulating my slab
Climate zone 4a. I am in the process of insulating my basement walls with 4″ of xps and had been planning on insulating my slab with 1/2″ or 1″ xps but as I read more and more on GBA I am now wondering if it’s even worth it. I will definitely insulate the exterior of my slab with 2-3″ of xps depending on how much I can get away with before it extends beyond my siding but after reading some of Martin’s comments to other people’s questions I am leaning towards forgoing the slab insulation. To one person he wrote that 1/2″ of xps is “fairly insignificant” and 1″ of xps “isn’t much”. If I went with 1″ of xps and two 1/2″ layers of plywood, plus 3/4″ flooring I would be 2 3/4″ higher which would cause problems at my exterior door and at the bottom of my stairs. I am on year 5 of building my house (owner/builder paying out of pocket) and am totally burnt out. Removing my exterior door that is glued with heavy duty liquid nails to a homemade sill pan which is glued to the slab with heavy duty liquid nails and having to modify my header and exterior trim is a no-go for me right now not to mention redoing my stairs so the height of my steps would be consistent. I have been racking my brain trying to figure out a way to rig something up so I can leave the door in place but have no feasible ideas. If I knew it was worth it I would take a break from working on the basement now and come back at a later date when I’m not burnt out and remove the door and redo my steps in order to insulate the slab with 1″ or even 2″ xps but if the efficiency gained from all this is minimal then I will forgo all slab insulation. So what say the experts?
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