Infill Materials used in Patent Glazing Systems

(a) Glass

The most common Infill material for use in patent glazing is glass. Its proven service life, excellent weathering performance and impressive product range make this material the number one choice for specifiers. The following types of glass are normally used in patent glazing: -

Annealed

(i) Transparent glass: clear float, body tinted float and polished wired glass
(ii) Translucent glass: clear patterned float and cast wired glass

Processed

(i) Toughened (tempered) glass: any annealed glass, with the exception of wired glass, that has been subjected to a heating and rapid cooling process that imparts a greater strength to the material. The process makes the glass more resistant to mechanical and thermal stresses.

(ii) Laminated glass: two or more panes of annealed or toughened glass usually laminated together by means of polymeric interlayers. The normal interlayer is poly (vinyl butyral). Great care needs to be taken when cutting laminated glass to ensure a good quality glass edge.

(iii) Double glazing units: factory made and hermetically sealed double glazing units which may incorporate any annealed, toughened or laminated glasses in any viable combination. (Due to thermal stresses, certain products should not be matched together). The panes of glass are separated by a hermetically sealed space of dehydrated air or an inert argon gas that reduces heat loss further. Low emissivity coatings, such as Pilkington ‘K’ can be applied to the inner surface of the bottom pane to give a considerable improvement in the units ‘U’ Value. High performance double glazed units that offer a low ‘U’ value and also help prevent heat gain into the building are available, but these products can have delivery periods in excess of ten weeks.

(b) Plastic glazing sheet materials.

Plastic glazing sheet materials are of various basic polymer types. The types marketed vary due to differences in their chemical composition or form, i.e. solid or hollow section. Whilst different types are normally available under their proprietary brand names, the basic types most commonly used in patent glazing are polycarbonate (PC)
These are available in both solid sheet and hollow section forms. In addition to clear transparent, some of the above are available as transparent colours such as bronze and opal.
Hollow plastic sheets, when used in patent glazing systems must be fitted with perimeter foil tape and special ‘breather’ tapes to allow ventilation into the unit. Failure to do this can result in a build up of moisture inside the panels and the possible growth of algae, which will discolour the material.

 

(c) Other materials

A wide range of materials, with or without insulation backings, may be used as infillings. These include:

• sheet aluminium insulated panels;
• sheet lead faced plywood panels;
• glass fibre reinforced plastic sheet (GRP);
• composite panels.