How to Kill a House | Insulating an Old Home in a Remodel- how to insulate an old house with wood siding ,31/8/2016· To insulate older homes, you must remove the cladding and weather barrier, drill the sheathing and blow or inject loose fill or foam insulation, replace the windows, install flashing properly integrated with the water resistive barrier, and replace the cladding, ideally adding a rainscreen.How to insulate interior walls in an existing houseHow to Insulate Walls in an Old House Apply a house wrap/vapor barrier to exterior walls . Attach 1-inch foam board insulation . Install siding over the insulation . Replace old windows with energy-efficient units. Caulk window trim and use weatherstripping to reduce air leaks.