Condensation

Left unchecked, condensation can damage window frames, sills, and interior shades. Water can deteriorate the surrounding paint, wallpaper, plasterboard, and furnishings. In severe cases, it can seep into adjoining walls, causing damage to the insulation and framing.
— US Department of Energy
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The build-up of condensation can be a serious concern for homeowners in the Pacific Northwest. 

Windows, Get ComfySarah Moon