Fasten window grille resistant

A window grille is one of the most reliable safeguards against burglary. However, in addition to a professionally welded model, a prerequisite is reliable attachment to the façade or soffit. Even a very durable window grille does not help if it can be broken out of the brickwork.


When a window grille is retrofitted, it can be applied to the facade or suspended in the soffit. For window grilles screwed to the facade, the screw heads must be made "inoperative". When installing, there are different functional models:

  • Disposable screws whose heads are sealed with rivets
  • One-sided rotating screws, which can only be moved in closing direction
  • Mounting screws are covered by additional cover profile

On the facade

Standard window grilles usually have four lateral mounting brackets, which are welded to the frame and placed on the facade. To prevent an eruption of the masonry edges, a minimum distance of eight centimeters to the reveal edge is common during assembly.

The minimum size of the window grille should be at least four centimeters overlapping the sides and the top edge of the window. The lower frame bar should float one to two centimeters above the windowsill if it is a flat window screen.

Arched grid shape

A "bulbous" window grille with semicircular bulge at the lower lattice body requires at least six attachment points. It should be mounted on the sides of each two and on the lower frame cross bar further two screw points.

Increasing the attachment points increases the resistance of the window grille against forcible breaking or chipping. Building experts speak of an optimal attachment, if no attachment point after attachment is more than fifty centimeters from the nearest one.

Flat grid in the soffit

If a flat window grille is bolted as burglary protection within the soffit, creates an approximately two centimeters wide gap between the grid frame and soffit. The screws are sheathed by spacers.

When mounting in this way, the depth of the screw connections and the sufficient strength of the screw threads are important because side levering tests can develop a tremendous force in a short time.

Tips & Tricks

If you have the opportunity, you should always consider the alternative of sinking the single bars of a window grille in the masonry or the soffit and thus offer no specific attachment points.

Video Board: How-to Install Aluminum Window Screen