Double Glazed Units

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Types and Durability

Description Double Glazed Units	Expected Lifespan (Years )	Adjustment Factors
Description Double Glazed Units	General	Adjustment Factors
Dual sealed units to BS 5713	25 Local warranty: ± 10 years for water tightness	1st stage adjustment factor: In industrial areas (heavy polluted): -15% of no. of years In urban areas: -10% of no. of years In suburban areas: no adjustment 2nd stage adjustment factor: Double glazed unit not fully bedded or fully drained (i.e. units fully bedded):-30% of no. of years. Within 20m from express way: -20% of no. of years Within 20m from major arterial road: -10% of no. of years Within 20m from light traffic road: – 5% of no. of years Test certificate from approved local testing authority : +15% of no. of years
Single sealed units to BS 5713	20 Local warranty: ± 10 years for water tightness
Single or dual seal units not comply with BS 5713	< 20	None

Combination of adjustment factors (1st stage and 2nd stage) should be added to obtain the durability values. Refer to durability calculator.

Note: Sealant used as glazing material must be compatible e.g. sealant based on linseed oil and acid polymerized silicone must not be used for double glazing unit.

The purpose of unit seal (around the edges of glasses) is to bond the two glasses together and to withstand the wind loading. The material used includes: silicon, butyl, and polysulphate. Acid based sealant must not be used against the unit seal. Nowadays, most of the double glazing units produced with dual seal method.