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PREZO Wrap is our own reflective sarking line — developed for commercial metal roofs where installers need a reliable heavy-duty laminate, consistent roll lengths and trade-counter support from our Campbellfield warehouse. Understanding how it performs thermally requires looking at the whole roof system, not just a number printed on a datasheet.
What reflective sarking actually does
Reflective sarking reduces radiant heat transfer across an air space. Its contribution depends on:
- Emissivity of the reflective facing — lower emissivity means less radiant heat emitted across the gap
- Air gap thickness — must be maintained and unobstructed; compression against the roof sheet kills performance
- Direction of heat flow — up, down or horizontal affects which R-value applies
- Dust and contamination — facing must stay clean to perform; install with the reflective surface correctly oriented
Unlike bulk insulation, reflective products are system ratings. The same roll can contribute differently depending on whether the roof space is ventilated, whether there is ceiling insulation below, and how the purlin cavity is configured.
PREZO Wrap product range
PREZO Wrap is supplied in configurations suited to commercial programs:
- Light, medium and heavy-duty facings — heavier facings resist tearing on wide purlin centres and during construction traffic
- Reflective laminate designed for typical metal roof install with supported spans per manufacturer data
- Compatible foil tapes from our sarking & wall wrap range for sealed laps
Download the PREZO Wrap data sheet for current technical values and span tables. Values are revised as testing updates — always use the latest publication on active projects.
How R-values appear on documentation
You will see several R-value descriptors in Australian insulation documentation:
- Material R-value — the product alone (often not meaningful for reflective laminates without context)
- System R-value — product plus defined air spaces and adjacent construction
- Total R-value — complete roof or wall build-up as assessed for NCC compliance
On commercial metal roofs without a ceiling, total performance often combines foil-faced roofing blanket plus any reflective air gap contribution. PREZO Wrap may sit as standalone sarking under sheet, or as part of a layered system — the energy report should state which.
Typical commercial metal roof scenarios
Scenario A — Sarking only under sheet, open roof space
Common on unlined sheds. Reflective sarking provides condensation control and modest radiant benefit. Bulk insulation may be absent; total R-value may rely heavily on air films and sarking. Confirm Section J or deemed-to-satisfy pathway with your certifier.
Scenario B — Foil-faced blanket plus separate sarking
Some specs double up unnecessarily; others model a specific system. Do not remove a layer without assessor approval. PREZO can quote ThermaRoof blanket and PREZO Wrap as a matched pack lot.
Scenario C — Suspended ceiling below
Reflective sarking still helps under the sheet, but ceiling batts may carry most of the thermal load. Ventilation between ceiling and roof becomes critical — see warehouse ventilation mistakes.
Install quality drives real-world R-value
The best specified sarking underperforms when:
- Facing is installed dull-side-out by mistake
- Insulation or mesh sags into the air gap
- Laps are unsealed and wind-wash pulls air through the cavity
- Foot traffic punctures facing before roof sheet install
Train crews to treat PREZO Wrap as a finished membrane — support at spans, tape laps, protect until sheet fix.
NCC 2022 and Section J context
Victorian commercial energy compliance often references NCC 2022 Section J. Roof total R-values depend on climate zone — Melbourne metro is typically Zone 6, with variations for alpine and coastal projects.
Provide your energy assessor:
- Exact product names and thicknesses
- Roof pitch and construction type
- Whether the roof space is ventilated
- Ceiling insulation type and thickness
PREZO's trade team can supply product data for assessor schedules — but the modelling stays with your energy consultant.
When to choose PREZO Wrap vs combined blanket
Choose PREZO Wrap standalone when the spec calls for reflective sarking only — retrofit sarking under existing sheet, or systems where bulk insulation sits elsewhere.
Choose foil-faced roofing blanket when one pass must deliver bulk R-value plus condensation control — common on new commercial metal decks.
Choose both only when the energy report or manufacturer system explicitly requires it.
Order and support
PREZO Wrap ships from Campbellfield with metro delivery across Melbourne and Victoria-wide programs. Request a quote with roof area, purlin spacing, facing duty required and target total R-value — we will align facing grade and roll quantities, including tape and accessories, on one commercial invoice.
Reflective sarking is not magic — it is precise physics installed correctly. PREZO Wrap gives Victorian roofers a dependable commercial-grade product with local stock and technical backup when the energy report asks hard questions.
