I'm going to remove a berber carpet glued to a concrete slab and I'm not sure how to prepare the slab for a finished floor.

I'm renovating a room in a finished, walk out basement. It's adjacent to another finished room and an unfinished mechanical room. I took it down to the studs.

I'm in the Northeast US, Zone 6b and the house was built in 1980. I don't know if there's a vapor barrier under the slab. There is EPS foam board on the outside of the concrete basement walls.

I did some research and found a 10yr old article from Building Science Corp. It describes 1" XPS insulation over a concrete slab and with a plywood floor on top. They say it provides a warm, dry surface to install a finished floor.

They wrote another article in 2009 describing a method with a vapor barrier under the concrete slab. The slab dries inward and a finished floor appears to be placed on top.

The interior framed wall has a 2x4 PT sill, the exterior wall has a 2x6 PT sill and both are fastened to the slab. From the first article, the 2" thick insulated floor they described would come up over the bottom 2x4 of the interior and exterior framed walls. I'm not sure that's a good idea but I don't know.

How should I prepare the floor for a carpet while keeping moisture out and the heat in?


  • It's not clear what you're asking. If the slab already had carpet on it, and there are no problems, what are you trying to accomplish? If your floor has not been comfortable, edit that into your title and post as the crux of the question. – isherwood Mar 27 '17 at 1:37
  • The article you reference, primarily references heat loss through WALLS not FLOORS, for good reason: Heat rises so heat loss is primarily through ceilings and secondarily through walls. Heat loss through floors is minimal compared to ceilings and walls. In addition, it is relatively easy to provide insulation in walls and ceilings. If you don't have a moisture problem, I'm not sure you should be messing with your existing floor system. Also, adding a few inches to the height of one floor could be a tripping hazard at doorways. If your direct glue carpet can be removed, I'd replace with same. – Lee Sam Mar 27 '17 at 3:22
  • @isherwood I'm removing the carpet, too – Mike Marseglia Mar 27 '17 at 10:48
  • @lee Sam yes, you are right those articles primarily talk about walls. But I'm guessing that's because there are fewer options for floors. Probably can't spray foam a floor. You have a good suggestion, just replace the carpet with same. – Mike Marseglia Mar 27 '17 at 10:50

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