Case 3

Maintenance and Diagnostics

Regular maintenance of glass curtain wall should be carried out with cleaning agents that will not affect the integrity or durability of the sealants or materials. Periodic inspections should also be made from inside the building during rainy days so that small leaks can located and repaired immediately. Faulty components should also be replaced before they allow water to penetrate.

The glass panels can be cleaned with regular or ammonia based cleaning agents. Try to avoid cleansers that leave a film or residue on the glass after cleaning.

Recommendation: building with more than 25% of façade in curtain wall shall be inspected every 6 to 12 months for deterioration of aluminium framing and condition of coatings, hardware, glass, sealants and weather seals. Regular inspection of sealant performance is necessary.

Diagnostics of Defect

Visual Inspection

Visual Inspection can be generally carried out.

Elastic Recovery Meter

In the case of sealant failure, an Elastic Recovery Meter can be used to check for its elasticity.

Field Adhesion Test

Low modulus sealants and sealants used to weather-seal, the most typical application, should maintain a constant bond line when the sealant is extended to two times its joint movement rating while being pulled perpendicular to the joint.

The procedure is as follows:

1. Cut out a 50-mm tab of the sealant, as shown in Figure.
2. Grab the tab at the 25-mm mark on the sealant and pull perpendicular to the joint or to the 37mm mark on the ruler for a sealant rated at ±25% movement, to the 50mm mark for a sealant rated at ±50% movement, and to the 76mm mark for a sealant rated at 100% movement. When pulling this tape, the bond line should not move.
3. The sealant should be wet (immersed if possible) and rechecked after 7 days of immersion.

Compatibility Test

The industry standard test for compatibility involves putting a gasket or spacer material on a piece of glass and extruding light- and dark-coloured silicon sealant onto the gasket with the sealant adhering to glass.

The procedure is as follows:

1. Sample is subjected to ultraviolet light at 2000 to 4000 µW/cm2 at 50°C for 21 days.
2. Check sealant for discolouration, adhesion to gasket, and adhesion to glass

Most neoprene, ethylene propylene diene monomer (EPDM), and some PVC gaskets will cause the sealants to discolour in this test. This discoloration is caused by the oils and plasticisers in the gaskets migrating through the silicone and oixidising on the sealant surface.

Sometimes, the sealant will lose adhesion to the glass, but this happens when severe discolouration is noted and migration is excessive. The adhesion of sealant to the gasket is also checked.