1980s Steel Portal Frame Defects Flashcards
Can you name some typical defects to 1980s steel framed buildings?
Cut edge corrosion to profiled metal roof sheets.
UV deterioration of roof lights.
Failed metal cladding coatings.
Composite cladding panels.
What are the symptoms of cut edge corrosion?
The protective coating starts to peel back at the lap joints.
What are the causes of cut edge corrosion?
When the roof sheets are cut in the factory, the coating is damaged and micro-cracking occurs which allows the admission of moisture leading to corrosion.
Water also gets trapped at the lap joint and the coating lifting exacerbates.
4) How do you remedy cut edge corrosion?
Clean the affected area and remove the defective coatings.
Gun apply a sealant to bridge to gap (25mm either side of joint).
Brush apply one top coat of seamsil (37mm) either side of the joint).
How do you identify that UV deterioration has taken place to GRP rooflights?
The exterior gel coat to GRP rooflights deteriorates and the glass fibres are exposed due to UV exposure.
The sheets become brittle and hard and are easily damaged.
Leaks become more likely as does moss growth.
Light transmission becomes reduced.
How would you remedy a UV deteriorated rooflight?
Replace the rooflight.
Or, apply a translucent resin coating such as Giromax Delgaze once the surface has been suitably cleaned and dried.
What are the signs of failed metal cladding coatings?
Plastisol, PVF2, etc coating starts to peel back and flake away in places.
Corrosion could be evident to exposed cladding below.
