Insulation, air sealingand windowshow the house feels.

Most older New Jersey houses have little or no wall insulation and leak air at every junction — sill plates, rim joists, top plates, around every penetration, and up through the ceiling into a cold attic. Insulation alone does not fix that, because insulation slows heat and does nothing about moving air. Air sealing comes first: rim joists sealed, penetrations foamed, the ceiling plane made continuous. Then insulation, to the depth and specification the assembly can actually accommodate without trapping moisture.

Windows are replaced while the envelope is open, which is the only time they can be integrated properly. A replacement unit dropped into an existing opening and caulked is a leak waiting for a driving rain; a unit set on a sill pan with head flashing lapped into the water-resistive barrier will shed water for its whole life. The difference costs very little at this stage and is effectively impossible to retrofit later.