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Picking the wrong base coat render for a substrate is one of the most avoidable problems on a render job — and one of the most expensive to fix after the fact. Poor adhesion, cracking, moisture issues, and failed inspections all trace back to the same root cause: the render system wasn’t matched to what it was going on.
Unitex manufactures a range of base coat renders specifically formulated for Australian conditions, covering the full spectrum of substrates found on residential and commercial sites. This guide breaks down which product suits which situation, so builders and renderers can get it right the first time.
What Is a Base Coat Render and Why Does Substrate Matter?
A base coat render is the foundation coat applied directly to the substrate — the layer that bonds the system to the wall and provides the build, strength, and surface profile needed for the finish coat. It’s the most technically demanding part of any render system because it has to adhere to a specific substrate while managing moisture, thermal movement, and structural loads.
Different substrates have fundamentally different surface profiles, porosity levels, and movement characteristics. Clean brickwork is porous and textured. AAC panels are lightweight but highly absorbent. Fibre cement sheeting is smooth and relatively non-porous. Painted brickwork has an existing coating that changes adhesion behaviour entirely. A render formulated for one won’t necessarily perform on another — which is why Unitex produces a range rather than a single product, and why each product is backed by published system specifications for documented substrate compatibility.
The Unitex Base Coat Render Range: Substrate by Substrate
Clean Brickwork and Blockwork
For clean brickwork, concrete blockwork, and similar masonry, the workhorses of the Unitex range are Polymer Render Wet and Polymer Render Dry. Both are acrylic polymer render formulations designed for strong adhesion to masonry substrates, with the wet pre-mixed option suiting sites where consistency and speed of application are priorities, and the dry powder option offering flexibility where storage or transport is a consideration. HiLite Render is another option for brickwork applications where a lighter build is appropriate.
For sites where the brickwork has been deeply raked — common on older homes where joints have been cut back to improve render key — Unitex has specific system guidance covering the appropriate build-up and product selection for this substrate condition.
AAC Panels
Autoclaved Aerated Concrete panels have become one of the most common substrates in new residential construction and extensions. They’re lightweight and thermally efficient, but their high absorbency requires a render that accounts for rapid moisture draw-out during application.
The new Aero Render is Unitex’s dedicated solution for AAC panels, clean brickwork, and concrete blockwork. It’s designed for single-coat application to thicknesses from a skim coat through to 10mm, finishing to a tight, smooth surface. It’s accessible for applicators at all skill levels, which makes it a practical choice for builders managing renderers across volume projects.
Fibre Cement Sheeting
Fibre cement sheeting requires careful preparation and the right render chemistry for reliable long-term adhesion. Unitex’s system specifications cover fibre cement as a documented substrate, and the technical team can advise on the appropriate product and primer combination for this application — particularly important on contemporary facade designs where fibre cement is specified alongside other substrate types on the same building.
Baseboard System (EIFS)
For projects using the Unitex Base Board lightweight cladding system, the specified base coat is Base Board Render BBR 8.5 — a render formulated specifically for application over the pre-coated EPS panels used in the Base Board EIFS system. This is a nil-substitution product within the CodeMark-certified system: using a different base coat render on Base Board panels would take the installation outside the certified system and void the accreditation. BBR 8.5 is the correct and only product for this application within the certified build-up.
Raw Polystyrene
For raw polystyrene substrates outside the Base Board system, Unitex’s system specifications provide guidance on the appropriate render and primer combination. This substrate type is less common but does appear on certain renovation and retrofit applications.
Non-Combustible Requirements
Where the NCC or a building specification requires non-combustible materials — Class 2 buildings, certain commercial applications, or projects where fire performance is specifically called out — Unitex offers a dedicated non-combustible base coat render range carrying AS 1530.1 accreditation, independently tested by CSIRO Materials Science.
Products in this range include Beach Render Non-Combustible, Fast-R Render Non-Combustible, Harbour Fine Non-Combustible, and Redi Render Non-Combustible. Each is formulated to meet fire hazard property requirements while maintaining the workability and performance characteristics needed for reliable application. For projects that also require a four-hour fire rating on panel joints or penetrations, Panel Patch (4hr Fire Rating) rounds out the non-combustible system offering.
How to Confirm the Right System for Your Project
The substrate guide above covers the most common applications, but render jobs rarely come in a single substrate type. Extensions, renovations, and multi-stage builds often involve two or three different substrates on the same project — each requiring its own specified build-up.
The most reliable way to confirm the correct render system across a mixed-substrate project is to use Unitex’s system specifications pages, which document the complete build-up — primer, base coat, and finish coat — for every supported substrate. Alternatively, the Unitex technical sales team can review your project specifics and recommend the right product combination before you order.
For builders pricing a job, the free Plan Quote Service lets you email plans through and receive a full materials calculation — useful when substrate types vary across elevations and you need accurate quantities for each system.
Australian-Made, Accredited, and Formulated for Local Conditions
Every product in the Unitex base coat renders range is manufactured in Dandenong, Victoria — formulated for Australian climate conditions rather than adapted from European systems. That means the products account for Melbourne’s temperature cycling, Sydney’s coastal humidity, Adelaide’s dry heat, and the UV exposure that Australian facades face across all regions.
With over 40 years of manufacturing experience and a team carrying more than 50 years of combined render expertise, Unitex has developed its base coat render range through decades of real-world application feedback — not just laboratory testing.
To explore the full range and find the right base coat render for your next project, visit the Unitex base coat renders product page or call the team on 1800 RENDER.
Call: 1800 RENDER (1800 736 337)
Email: sales@unitex.com.au
System Specifications: unitex.com.au/system-specifications/
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