Protective Glazing

In recent times, double glazing or protective glazing has become widely used to help protect works of historical significance from damage. In particular, damage may occur where leadlight or stained glass are located next to playgrounds or where windows are close to the street. In the future it may become standard practice to double glass window in new houses to comply with regulations relating to energy efficiency.

There are a number of different materials that can be used for protective glazing, each with their advantages and disadvantages. A list of some common protective glazing is shown below.

Protective Glazing

Types of Protective Glazing Pros Cons
Float Glass Can be cut on site thus reducing cost.Best suited for timber frames and straight edged windows or windows with a slight curve. Retains heat which can cause lead fatigue if not installed isothermally.Not as strong as “A grade” safety glass and can only be cut to simple shapes.
Toughened Glass A lot stronger than float or laminate.Robust against vandalism and colour change.

Glass is able to be thinner than laminate which may help with installation.

Best suited for timber frames and straight edged windows or windows with a slight curve.

Retains heat which can cause lead fatigue if not installed isothermally. Can only be cut to simple shapes.
Laminate Glass Helps maintain optimal temperature around window to be protected.Can be installed easily.

Can be cut to obscure shapes.

Semi robust against vandalism.

Only has a 10 year guarantee against yellowing and can scratch easily.Semi robust against vandalism.
Poly Carbonate Helps maintain optimal temperature around window to be protected.Can be installed easily.

Doesn’t turn yellow as quickly as Perspex.

Can be cut to obscure shapes.

Semi robust against vandalism.

Has a life time guarantee (25 years) against yellowing.Can scratch easily.
Wire Screens Allows air flow to the window which reduces lead fatigue.Can be made into obscure shapes.

Robust against vandalism.

Can rust over time (40 years +) cause brown oxidation on the lead.This can be reduced by using stainless steel in the screens and then powder coating them. More difficult to install.