Installing plywood over 1x6 subfloor in preparation for engineered hardwood.
Rigid foam over subfloor.
Leave a 1 4 inch gap around the perimeter.
The foam butts against the mudsills for a complete thermal break.
Tape the seams of the foam panels with heavy duty construction tape.
There are several ways to install subflooring above the rigid foam.
Use a utility knife to cut the foam to size a hacksaw or drywall saw also work well for this.
Proper subfloor for hardwood in a renovation.
Two layers of 3 4 inch osb subflooring then float unattached on top of the foam to provide a solid and stable underpinning for the wide board wood floors.
Plywood screwed down through the layer below.
The polyethylene sheet becomes part of a continuous air barrier for the home.
Every 8 on the edges and 12 in the center.
Then i glued osb sheets to the foam board.
While all foam insulation products are derived from petroleum some of the key differences include water resistance r value per inch compressive strength facings permeability to water vapor and evidently cost.
Lay sheets of high density rigid foam over the polyethylene.
Use t g and screw through the foam and the into original floor to keep the large sheets flat.
I glued 1 inch thick rigid foam board onto the concrete floor which i had previously treated with a 1 16 inch coating of xyprex moisture proofing.
Expanded polystyrene eps extruded polystyrene xps and polyisocyanurate are the most used types of rigid foam insulation.
For your install plywood will work fine.
This will also help eliminate the hollow sound and feel the floor will have over the foam.