I wonder if our GC's proposal is overkill. We've just installed new PEX radiant heat panels over existing slab on grade, and now are considering having tile rather than 5/8" engineered wood above the radiant panels (Rehau Raupanel, 8" OC). The Raupanel installation specs diagram for tile installation shows the following layers: - ceramic tile (1/4" typical) - cement or mortar compound w/ mesh or rubber membrane (1/4" typical) [e.g. Schulter Ditra?] - Raupanel + PEX + furring strips - vapor barrier - concrete slab Our GC claims we need to: -tear out the Raupanel and furring strips. -have loops of Pex with a concrete overpour, -then plywood base, a 1/2" backerboard, - and finally the tile in thinset (I think). What's going on? I think the GC said this is for sufficient isolation from expansion, and the tear-out needed to keep the assembly from being almost 1" higher than the adjacent room (5/8" Owens Plankfloor above Raupanel). But some of the GC's solutions have been un-nece$$arily labor-inten$ive, so I've become alert to padded proposals. BTW, His partial quote, for the 50 sq ft room is: "Demo the existing wood furring strips and float the floor and install the owner provided tile. Total cost 2,100.00 (Note the base will be wood provided in an alternate price)" Does that make sense? What should I do next? ------ PS. Should we even be doing tile, vs. e.g., linoleum, if we may have a litter-box and/or pet food bowls in the room? I started imagining urine odor in grout....

I was thinking fire hazard as well. That doesn't really sound like it is up to current code either. I think the floor part of the problem is fineâ¦you can lay another floor over it. But at this point with the wires etc. under there I would look at a floating click-installation wood floor. I would not be driving nails into a nest of electrical wires.

Either option will need a foundation, HVAC, electrical, and probably plumbing. The first couple of feet of any addition always cost the most, and after that, the cost per square foot go down because you've already accounted for the expensive stuff. Often, it makes more sense to create new family or dining space because it's cheaper, and then take over the old family or diing space for the kitchen.

As Milly and Joseph said, you would have to open up a few places to see your framing details etc, I mean if you have experience and knowledge you would pretty much know how the framing is and what is being carried by what and you will have to make an opening, but existing joists, double up some existing, pretty much like you would make a pulldown downstairs, the concept is the same. Stairs can be built onsite depending on the staircase you want to have if it's just a boxed set of stairs between the 2 walls, it's very easy to make them onsite, again have to know carpentry. In any case, you will need an architect, a set of drawings, building permits, etc but this is pretty much what needs to be done just to give you an idea. If you think you can do it, nothing wrong with it to try or at least you can do what you can and hire someone to do what you can't do. I remember in my old house, a couple a few doors down build a 2 story addition, they had some family members helping them lift the walls, etc and they hired a contractor to frame the roof and do the sheeting. The guy I think owned a car parts store and the wife was a nurse. Little by little they did everything. Good luck.