Window defects

Window defects are common, especially in new apartments. Builders do not always meet the aluminum window sill standard or get the sill height right. This article covers how to check window heights in a new house, and everything related to the aluminum window sill.

Article written by: Ron Arad, civil engineer
Arad, a home inspection company

New apartments today almost always have aluminum-framed windows with safety glass, single or double glazed. That may sound simple, but a new window that meets the standard is no guarantee against construction defects. Here are some of the problems a home inspection engineer may find when checking windows for construction defects.

Installation problems: dimensions, sill height, and straight walls

A window is installed after the wall is built, which requires careful planning: precise opening dimensions, precise sill height, and straight walls. When any of these is not planned or executed properly, problems follow.

1. Inaccurate wall-opening dimensions: an opening too large for the window, if not handled properly, leaves a gap between the frame and the wall that can let in water and cause cracks.

2. Incorrect sill height.
   Here the wall opening is too low relative to the planned sill.

   

   The aluminum contractor installs the window at the planned height regardless, leaving an unusual gap between the sill and the wall. That gap is usually filled with block fragments or mortar, which creates problems that only surface after you move in, mainly cracking and, in more serious cases, dampness. The fix is to remove the window, take out the filling, and pour a concrete tie beam up to the sill height. A home inspection usually identifies the repair needed and gives you grounds to require the contractor to make it before the problem gets worse.

3. Crooked walls: a wall that is not straight makes the window protrude from it.
   The aluminum contractor has to install the window level in every direction regardless, or it will not open and close properly. So if the wall is noticeably crooked while the window is installed straight and level, an unusual gap opens between them, usually filled with silicone.

   

   That looks bad, and after a while the silicone starts to peel, again letting in dampness through the poor seal. Caught in time, during construction or before you move into the new apartment, you can require the wall to be straightened and the window reinstalled. The best time for that change is before you move in.

Coordinating and supervising the wall construction and window installation properly prevents all of this. Where that coordination was missed, a construction-defect inspection will find the deviation.

Defects in the window itself

A home inspection checks many things, including a leak in the ceiling from the neighbor above, cracks, and windows. Here are defects in the window itself, apart from the wall:

1. Glass defects: at handover the windows are often very dirty, which hides scratches. Bring a damp cloth to the handover and clean the windows thoroughly. If you do not report a scratch at handover and only notice it after moving in, the contractor may claim you caused it. The standard the contractor must meet allows up to one scratch, of a limited length. Other glass defects include bubbles and staining.

   

2. Seals: seals sit between the glass and the frame to keep out water and wind. They must be intact, thick, and long enough to cover the full gap between glass and frame, and a home inspection routinely checks this.

3. Insulated glazing: when is it required, and when not, for cold and heat transfer? It is a complex subject on its own, but in short, Israeli Standard 1040 for thermal insulation sets minimum parameters, and the apartment's walls, windows, and doors have to be designed together to meet them, based on location and floor height.

Why sill height and window standards matter

The flooring standard and window standards are both building-compliance milestones. A tenth-floor apartment in Jerusalem, for example, needs stricter thermal insulation than a ground-floor house in Tel Aviv, which can call for insulated glazing: two panes with an air gap between them, rather than a single pane with weaker thermal properties.

You can usually tell the two apart just by looking. Installing windows looks simple but is a skilled trade: done poorly, the result shows both in looks and in function, from cracks and windows that operate badly to, worst of all, water penetration and condensation. See our article on condensation.