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Windows: repair or replace?

Most homeowners with older windows begin with one question. This guide helps you answer it with reliable facts instead of sales pressure.

The short answer

  • Drafts, fog between the panes and sticking sashes are the most common warning signs.
  • A worn seal, lock or sash can usually be repaired, while a rotted frame typically needs a new window.
  • The frame material, the type of glass and the installation labor determine most of the final price.
A double-hung window with arrows showing both sashes slide up and down.

How do homeowners know a window needs work?

Homeowners usually notice drafts first, followed by fog or moisture inside the glass. A sash that sticks or refuses to stay open is another common warning.

  • Cold air leaking around the window frame on a windy winter day.
  • Moisture or a milky haze between the panes that never wipes away.
  • Soft, discolored or peeling wood around the frame and the window sill.
A window with fog trapped between the panes.Before
The same window with clear glass after the glass unit was replaced.After
Fog between the panes means the seal failed; new glass clears it.

What are the parts of a window?

A window has a fixed frame and a movable sash that holds the glass. Knowing these names helps homeowners understand every line of a contractor estimate.

The parts of a window

A window with five numbered parts: frame, upper sash, glass, sill and lock.
  1. Frame: the fixed box that holds everything.
  2. Sash: the part that moves and holds the glass.
  3. Glass: one, two or three panes.
  4. Sill: the ledge at the bottom that sheds water.
  5. Lock: it pulls the sashes tight to stop drafts.
Homeowners usually replace the sash and glass, the frame, or both.

See inside a window

Rotate the model to see how the parts fit together. The cutaway side shows both panes of glass and the spacer between them.

Drawing of a window cut open on one side. It shows the frame, the two sashes and the two panes of glass with the spacer between them.

Frame material

Parts of the window

  • Frame: the fixed outer box installed in the wall opening.
  • Sashes: the movable frames that hold the glass and slide up and down.
  • Insulated glass: two panes separated by a sealed, insulating gap.
  • Spacer: the strip that separates the two panes and seals the gap.
  • Sill: the sloped ledge that directs rainwater away from the wall.

Drag the model to rotate it. The buttons and the arrow, plus and minus keys work the same way.

The model is a simplified drawing, not to scale. Switch to the roof to explore the layers under the shingles.

Which window styles are there?

Four styles cover most American homes. Each style operates differently, which affects ventilation, cleaning and the eventual price.

  • A double-hung window with arrows showing both sashes slide up and down.
    Double-hung
  • A casement window swung open on its side hinge.
    Casement
  • A sliding window with an arrow showing one sash slides sideways.
    Sliding
  • A large picture window that does not open, with a view of hills.
    Picture

Should you repair or replace a window?

When does a repair make sense?

A repair makes sense when the frame is solid and only one component failed, such as the weatherstripping.

When is it time to replace the window?

Replacement makes sense when the frame is rotted or warped, or when homeowners want better glass everywhere.

Can a professional replace only the glass?

Often, yes. When only the seal around the glass failed, a new sealed glass unit usually costs less than a complete window.

Do new windows lower energy bills?

They can, especially when certified windows replace old single-pane windows. Look for the ENERGY STAR label for your climate zone beside the NFRC label.

Energy bill savings when certified windows replace single-pane ones

up to 13%

Source: ENERGY STAR (U.S. EPA), Residential windows, doors and skylights,

Where should you go next?

Sources

  1. ENERGY STAR (U.S. EPA), Residential windows, doors and skylights Checked

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