this depends on a number of factors. is it internaly or externally glazed? is wedge gasket or glazing tape used?
if it is internally beaded then using a strong thin blade (decorators scraper will suffice; don carlos knife preferable) tap in inbetween bead and frame and then ease in towards centre of window moving up and down joint until bead comes out. repeat this process on all beads. remove unit.
if externally beaded and wedge gasket then using (scraper) remove gasket from inside first; remembering to note which way it comes out.this will free the unit making it easy to de-bead. fit new unit, re-bead, re-gasket.
if glazing tape has been used then this will need to be freed from glass first by sliding a sharp knife around edge of unit then de-beaded. this tape will need to be replaced, make note of thickness.
once unit is out you will not find any measurements but you can measure glass that is intact, make sure you measure the thickness (this is important).
16, 18, 20, 22, 24, 28mm units are all still used.
if you break the remaining glass then measure as follows. for e.g. if aperture is 500mm wide by 500mm high then the unit size will be 490mm x 490mm. i.e. take 10mm off h and w.
levi lewy
July 2008
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