Doors, windows and glazing

6.7

6.7.7Glazing

Glass and the method of glazing shall be installed in accordance with the design and to ensure adequate in-service performance. Issues to be taken into account include:

  1. standards
  2. glazing compounds
  3. glazing systems
  4. insulating glass units
  5. condition before installation
  6. sizing
  7. rebates
  8. bead glazing.

Standards

Where there is a high risk of accidental breakage, glazing should be designed and selected to comply with relevant building regulations.

Where there is a particular risk (such as door side panels or ‘low level’ glazing) and where fully glazed panels can be mistaken for doors, toughened or laminated glass, or other materials such as acrylic or polycarbonate, may be required.

The glass supplier should provide documentation to confirm:

  • the properties of the glass used
  • compliance with the appropriate British Standards.

Glazed materials and units should be:

  • compatible with the levels of safety and security that are required
  • identified as safety glass with a permanent marking (includes glazed shower/bath screens).

Glazing should ensure adequate in-service performance. The quality and thickness of normal window glass should:

  • be specified to suit the design wind loads for the location
  • comply with BS 6262 and relevant data sheets issued by the Glass and Glazing Federation.

Glazing and materials should comply with appropriate British Standards, including:

BS 5516‘Code of practice for patent glazing’.
BS 6262‘Code of practice for glazing of buildings’.
BS EN 1279‘Glass in buildings-insulating glass units’.
BS EN 572‘Annealed glass’.
BS EN 14449‘Laminated glass’.
BS EN 12150‘Toughened glass’.
BS EN 572‘Wired glass’.
BS EN 1096‘Low-e coated glasses, including hard and soft coated’.

Glazing compounds

Glazing compounds should:

  • be compatible with the frame finishes
  • be in accordance with the manufacturer’s recommendations.

Linseed oil based putty should not be used in the installation of laminated glass or insulating glass units.

Glazing systems

Drained and vented systems

Drained and vented systems should be used for site fixed insulating glass units and where units greater than 1m2 are used, to allow moisture that enters the glazing channel between the frame and the edge seal of the insulating glass unit to drain away and prevent long-term moisture contact with the edge seal. Drained and vented systems should have:

  • a minimum 5mm gap between the frame’s lower rebate and the edge seal of the insulating glass unit
  • adequate drainage and ventilation through holes, slots or channels
  • the edge seal of the insulating glass unit adequately protected.

Fully bedded systems

Fully bedded systems are acceptable for factory glazing only where the insulated unit is less than 1m2, and should:

  • comply with the relevant parts of BS 8000, BS 6262 and BRE Digest 453
  • not have gaps around the perimeter of the insulating glass unit.

Partially bedded insulating glass units may be fixed on site where bedded at the top and sides, providing the rebate platform is drained and vented.

Site glazed systems

Where doors and windows of materials other than timber are delivered to the site unglazed, all glazing should be carried out in accordance with the manufacturer’s instructions.

Appropriate fixing and sealing systems should include:

  • distance pieces, unless load-bearing tapes are used
  • setting blocks
  • location blocks, where required
  • appropriate beads
  • suitable glazing compounds, sealants, gaskets and/or capping.

Beads

In external situations, the bottom bead should:

  • project slightly over the rebate edge
  • be fixed to the rebate platform.

Insulating glass units

Insulating glass units should:

  • carry a CE mark to BS EN 1279 and have third-party certification, e.g. BSI Kitemark
  • be checked to ensure they comply with the design, including glass type, gas filling, edge seal type and dimensions
  • have a dual seal or a single seal of hot melt butyl and desiccant in at least one long and one short section of the spacer bar.

Condition before installation

Glass and insulating glass units should be inspected for both visual defects and those which could lead to premature failure. Defects can be caused by:

  • water accumulating between sheets, which may cause internal surfaces to become marked
  • edge damage or scratching.

Insulating glass units should be adequately protected when stored prior to installation.

Sizing

To account for thermal expansion, the following gaps should be provided:

  • 3mm gap between the glass edge and the frame
  • 5mm gap at the bottom bead for drained systems.

Insulating glass units should not be cut or punctured on site.

Rebates

Rebates for glass should be:

  • the correct size for the glazing
  • primed where timber
  • rigid and true.

Insulating glass units should be:

  • protected from sunlight at the edges by the frame
  • positioned to ensure the spacer bar is below the level of the frame’s sightline.

Setting and location blocks should be of a suitable and resilient material.

In drained and ventilated frames:

  • dimensions of holes and slots should be checked to ensure that effective drainage can occur
  • drainage channels in the rebate should be free from obstructions that could prevent effective drainage.

Bead glazing

Beads and linings should be used for:

  • internal glazing
  • locations where shock absorption is required.

Beads should be fixed at a maximum of 150mm centres.