Find the layer that holds the haze

Wipe a small area of the room-side glass with a clean cloth. Check the exterior surface only if you can reach it safely from ground level. If the patch remains behind both surfaces on a sealed double-pane window, moisture inside the insulated glass assembly is a possible explanation. A separate removable storm panel creates a different air space, so tell the supplier if your window has one.

Ask what the supplier can actually replace

The insulated glass unit is the sealed assembly of panes and spacer. The sash is the frame directly holding that glass. Some designs accept a replacement glass unit. Others are serviced as a complete glazed sash. The surrounding window frame is a third part. A quote that simply says “replace window” leaves all three possibilities open.

1 · Glass unit

The sealed panes and the spacer between them.

2 · Sash

The frame immediately around the glass. Some makers supply these together.

3 · Window frame

The surround attached to the opening in the wall.

Build a useful photo set

Take a photo of the entire window from indoors, another of the cloudy area, and a close-up of any corner etching or product label. Include whether the window slides, swings outward or is fixed. If several windows look alike, label the photos by room. Ask the manufacturer to check the series, age and any glass warranty before requesting an installed price.

Compare the same scope

Ask each company to name the part supplied, whether labor and disposal are included, and how it will match the adjacent glass. If someone proposes a complete frame, ask what condition of the existing frame requires it. That detail helps distinguish a failed sealed unit from a second problem such as rot or water entering around the opening.

For more detail, see Andersen’s replacement sash and glass guidance. Related reading: the guide to insert versus full-frame windows.