The standard adopted in the UK glass industry, is to measure in millimetres (mm). Always give the WIDTH (first) x HEIGHT (second), this is most important for patterned glasses and insulating glass units with square/diamond leads, Georgian Grills or Duplex Bars.

  1. Annealed – Standard glass as made by the Float or Rolled plant process by the glass manufacturers.  Breaks into large and sharp fragments that can cause serious injury.
  2. Toughened – Annealed glass, arrissed as standard, heat treated and breaks safely into small pieces that will only cause minor injury. Cannot be cut or drilled after toughening but has over seven times the strength of annealed glass.
  3. Heat Soaked – A further process after toughening.  To eliminate spontaneous breakage in toughened glass from Nickel Sulphide inclusions. Normally used on thicker glass glazed at high level or high risk glazing
  4. Heat Strengthened – A heat treatment carried out to annealed glass to add strength.  It’s state is somewhere between annealed and toughened glass.  Used only in special applications.
  5. Horticultural – Annealed glass for use in greenhouses and sheds where optical quality is not important and compliance to BS6206 is not required.
  6. Annealed Laminated – Two pieces of annealed glass with an EVA, PVB or resin interlayer, breaks safely and normally is retained within the aperture on breakage.
  7. Toughened Laminated – Two pieces of toughened glass generally with an EVA, PVB interlayer.  Normally used in structural applications such as floors and free-standing barriers.
  8. Silvered Float – Annealed float with a mirror backing applied shortly after being made.

Glazing in timber

A glazing clearance is normally the tight opening size minus 6mm giving a clearance of 3mm all round. For larger pieces a larger clearance may be necessary.  Smaller heritage glazed sizes can have finer allowances of 4-5mm from tight-size. lf you are not giving a finished glazing size, you must state this at the time of ordering, unqualified sizes will be taken as the glazing size.

Glazing in uPVC and Aluminium

Normally the tight opening size minus 10-12mm giving a clearance of 5-6mm all round. For larger pieces a larger clearance may be necessary.  lf you are not giving a finished glazing size, you must state this at the time of ordering, unqualified sizes will be taken as the glazing size.

Use a hard material that is not too thick. We may scan your template on our CNC machine; the more accurate your template the greater the accuracy of the finished article. A template should be the actual size required and need no additions or subtractions to it. Mark the face (viewed) surface. All templates should be made as viewed from the outside. We do not accept paper or cardboard templates.

The rate of heat loss per square metre for a temperature difference of 1 degree Kelvin, or Celsius, between the interior and exterior.  Only taking into account loss through glass and cavity.  Not glass edge and sealants.

Using either low-e glass with an inert gas generally gives optimal performance when used in conjunction with a 16mm cavity.   There are now varying grades of low-emissivity glass and three inert gasses to choose from. These being Argon, Krypton and Xenon.  As cavity sizes decrease, higher performance materials and gases are required to maintain performance. We can advise what combination will get the results you require.

Clear glass will allow heat from the sun to enter the building un-controlled, contributing significantly to internal temperatures.

Solar heat gain can be controlled by using a solar control glass. These can be glasses with special coatings or body tinted floats such as blue, bronze, grey and green.

Glazing should be in accordance with BS8000. See our Arbo Heel Bead Glazing System download for the basic method; contact us for other types of glazing and glazing of self-cleaning glass.

Frames should be of sound structure and primed with suitable materials. Aggressive timbers such as green oaks especially, so as to prevent acids leaching through into unit sealants.

Units that are not glazed with suitable materials or following our guidelines will be void of warranty.

Frames should be dry, drained and ventilated. Units should be installed on suitable glazing blocks and equally supporting both glass panes. Blocks should be placed in the appropriate positions to offer support and rigidity to the glazed assembly throughout service.

The correct overall thickness unit should be specified upon order.

The glazing method for plastic frames is specific to system manufacture. If you are unsure you should seek the services of an experienced glazier/installer.

See our download page for Operation and Maintenance document.