The prevalence of decramastic (pressed metal tile) roofs in Rotorua
neighborhoods like Lynmore and Glenholme represents a specific
maintenance niche that requires extreme technical caution. These Roofs, consisting of galvanized steel tiles coated in a bitumen-based mastic and stone chips, are highly susceptible to the
corrosive effects of the Rotorua air. As the bitumen ages and
becomes brittle due to UV exposure and sulfur interaction, the
stone chips are lost, exposing the underlying steel to accelerated
oxidation.
A primary trade challenge in professional roof painting is the potential for asbestos contamination. Many decramastic tiles manufactured before the mid-1980s utilized asbestos fibers within the mastic coating to provide structural binding and fire resistance. High-pressure water blasting—a standard cleaning method for other roof types—is strictly prohibited on these tiles if they contain asbestos, as it can release hazardous friable fibers into the surrounding environment.
Tomar Contracting adheres to stringent WorkSafe NZ protocols
when assessing these structures. The process begins with a
professional asbestos survey, which typically costs between $400
and $800, to determine the safest course of action. If asbestos is
absent, the restoration proceeds with a focus on chemical
sterilization to remove moss, lichen, and algae that thrive in the
rough surface of the tiles. If asbestos is present, specialized roof restoration techniques must be employed, which may include encapsulation rather than removal, providing a safe and cost-effective alternative to a full roof replacement, which can cost upwards of $10,000.
The restoration of a non-asbestos decramastic roof involves a
multi-layered coating system:
- Corrosion Inhibitors: Apply rust etch primers to any exposed steel valleys or edges.
- High-Build Base Coats: Apply a thick acrylic layer to rebind any loose granules.
- Stone Chip Re-surfacing: If the original texture is significantly lost, new granules can be embedded in the base coat.
- Acrylic Glaze Topcoats: Two to three coats of a UV-resistant, semi-gloss finish to provide a water-shedding surface.
Beyond protection, modern roof painting services offer significant thermal benefits. By selecting light-reflective coatings with a high Light Reflectance Value (LRV), homeowners can reduce the solar heat gain of their attic spaces. This is a critical consideration in Rotorua, where the combination of intense sunlight and geothermal ground warmth can result in excessively high indoor temperatures during the summer months.
A professionally restored roof not only extends the lifespan of the
structure by 8 to 12 years but also significantly enhances the property's curb appeal. For homeowners looking to maintain their property’s value, hiring those who understand the intricacies of metal tile restoration is an essential step in asset management.
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