Primers and bonding agents — balcony waterproofing

System Description

ARDEX WPM 265 is ARDEX's general-purpose water-based acrylic primer for porous substrates prior to the application of ARDEX water-based liquid applied membranes (WPM 002, WPM 130, WPM 157, WPM 155, WPM 910 and similar). It is red pigmented — primed surfaces are easily identified visually during inspection, confirming coverage before membrane application commences. WPM 265 is a penetrating primer — it seals the pores of absorbent substrates, reducing the risk of pinholes or bubbles in the subsequently applied membrane caused by air escaping from an unprimed porous substrate. Apply by brush, roller, or low-pressure spray at approximately 6m² per litre. Allow a minimum of 1 hour recoat time. Apply membrane within the same day of priming to avoid intercoat contamination — do not leave primed surface overnight without overcoating or re-priming. WPM 265 is designed principally for internal use but can also be used for external applications. It is not suitable for damp, green, or high-moisture concrete — use ARDEX WPM 300 (HydrEpoxy) on substrates with elevated moisture content.

System Description

ARDEX WPM 300 (HydrEpoxy) is ARDEX's two-component water-based epoxy moisture barrier and primer coating. It is not an acrylic primer — it is an epoxy system used specifically where the concrete substrate has elevated moisture content, is freshly laid (green), or is producing efflorescence, and where a standard acrylic primer such as WPM 265 is not appropriate. ARDEX specifies WPM 300 as the mandatory primer when substrate moisture content exceeds 80% relative humidity (ASTM F2170) or 15g/m²/24hrs (ASTM F1869) — typically equivalent to 5% or greater moisture content from a digital non-destructive moisture meter. On occupied balcony remediation projects where the existing concrete slab may retain significant residual moisture, WPM 300 is the correct primer selection. WPM 300 can withstand 250kPa of hydrostatic pressure (equivalent to a 25m head of water) when applied to the substrate — functioning as both a moisture barrier and a waterproofing membrane in tanking applications, including potable water containment. Complies with AS 4020:2000 and British Standard 6920 for use in contact with potable water. Recoat time: 4 hours minimum. Maximum overcoat window: 72 hours — membrane must be applied within 72 hours of WPM 300 application or the surface must be re-primed. Sand blinding of the wet WPM 300 surface with ARDEX primer sand extends the overcoat window and is recommended practice for external tiling applications. Available in grey and Mojo Black.

System Description

ARDEX WPM 240 (Shelter Primer) is the mandatory solvent-based bitumen primer for use on concrete substrates prior to installation of ARDEX's torch-on modified bitumen sheet membranes (WPM 150, WPM 185) and self-adhesive sheet membranes (Shelterseal range). It is not a water-based or acrylic primer — it is a solvent-based bitumen cut dissolved in mineral spirits. Its function is to seal the concrete substrate and provide the tackified surface to which the bitumen sheet membrane bonds. Do not substitute WPM 240 with a water-based or acrylic primer under torch-on or self-adhesive bitumen sheet systems. The solvent carrier in WPM 240 penetrates the concrete surface and leaves a bitumen film that is chemically and physically compatible with the modified bitumen sheet membrane applied over it. A water-based primer does not achieve this and will result in inadequate bond between the sheet and the substrate. Apply by brush or airless spray. Allow the primer to become fully tack-free before installing the sheet membrane — a tacky but not wet surface is the correct condition for sheet installation. Coverage is approximately 5m² per litre, varying with substrate porosity. The product has a strong solvent odour — adequate ventilation is required. The product is flammable — store and use away from ignition sources. Note: WPM 240 primer is only required between the primed concrete substrate and the first sheet layer — it is not required between the base sheet and cap sheet layers.

System Description

SikaTile-010 Secure Prime is Sika Australia's general-purpose water-based primer for porous substrates prior to the application of Sika water-based waterproofing membranes and tile adhesives. It functions as both a surface sealer on porous substrates (concrete, screeds, renders, fibre cement) and as a priming coat on dense or steel-trowelled concrete surfaces — reducing the risk of efflorescence by using a unique crystalline technology that reduces the porosity of concrete, screeds, and renders. SikaTile-010 is suitable for internal and external use, including submerged applications such as tiled pools and spas — making it one of the more versatile primers in this category. The product is milky white liquid, dries clear. Apply by brush, roller, or low-pressure spray at approximately 13m² per litre depending on substrate porosity. Allow primer to dry before applying the waterproofing membrane or tile adhesive. Compatible substrates include concrete, cement boards and sheets (including Scyon), plasterboard, glass-reinforced concrete, cement-based screeds and renders, compressed fibre cement, masonry, and most standard construction boards. Early-aged concrete must be minimum 7 days old at 22°C / 50% RH before priming. Early-aged cement-based screeds must be minimum 24 hours old per 40mm of thickness.

System Description

Tremco Torch Bitumen Primer is the mandatory solvent-based primer for concrete substrates prior to installation of Tremco's TREMproof Torch 3000 and TREMproof Torch 4000M APP modified bitumen torch-on sheet membrane system. As with all bitumen sheet primer systems, this is a solvent-based product — not a water-based or acrylic primer. The solvent carrier penetrates the concrete surface and deposits a bituminous film that provides the chemical and physical bond interface for the torched APP sheet membrane. Apply at a rate of 6–8m² per litre. Allow the primer to become fully tack-free before membrane application. The primer must not be wet when the sheet is applied — a fully dried, tack-free primer surface is the correct condition. Tools and equipment are cleaned with Tremco Xylol solvent immediately after use. The Tremco Torch Bitumen Primer is part of Tremco's complete torch-on membrane system. Tremco requires that the primer and membrane be from the same Tremco system for system warranty to apply — do not substitute a third-party primer under TREMproof Torch membranes without confirming compatibility with Tremco CPG Australia.

System Description

Fosroc Nitobond SBR is a modified styrene-butadiene rubber (SBR) polymer emulsion used as a bonding agent and admixture for cementitious systems in balcony waterproofing and remediation. It is not a standalone primer or membrane — it is added to site-batched cement-based mortars, screeds, renders, and slurries to improve their adhesion, water resistance, flexibility, and durability. In balcony waterproofing remediation, Nitobond SBR is most commonly used in two ways: as a bonding slurry applied to prepared concrete before repair mortars or screeds, and as a gauging liquid added to cement powder to produce a polymer-modified primer slurry or waterproof render. In conjunction with Fosroc Nitoproof 410 cementitious membrane, a sand/cement slurry primed with Nitobond SBR is mandatory for submerged applications such as tiled pools and water tanks. Nitobond SBR improves tensile and flexural properties — allowing thinner applications of repair mortars — and produces mortars resistant to freeze/thaw cycling and waterproof renders with reduced permeability. Resistant to hydrolysis — suitable for external and permanently submerged applications. Supplied as a ready-to-use white liquid. Distributed in Australia by Parchem Construction Supplies.

System Description

Gripset 11Y is a concentrated SBR (styrene-butadiene rubber) latex polymer admixture that is added to cement-based mixes to upgrade their performance for high-bond, durable, and water-resistant applications. Like Fosroc Nitobond SBR, it is not a standalone primer or waterproofing membrane — it is an admixture that modifies cement-based systems used in and around waterproofing installations. In balcony waterproofing remediation, Gripset 11Y is used to produce polymer-modified primer slurries applied to concrete substrates before Gripset liquid membranes (38FC, BRW systems), to improve the bond and durability of cement screeds and renders that form part of the waterproofing system, and to upgrade repair mortars applied to balcony concrete before membrane application. It is also confirmed for use over bitumen substrates as part of a preparation system — Gripset 11Y slurry over bitumen substrates before Gripset RD acrylic membrane. Substrate compatibility is broad — confirmed for concrete, masonry, renders, concrete blocks, aerated concrete, clay bricks, pavers, cement sheeting, marine plywood, wet area particleboard, asphalt, cured bitumen, and existing acrylic coatings. This makes Gripset 11Y practical on remedial balcony projects where the existing substrate includes a range of materials. Australian manufactured by Gripset Industries.

System Description

Fosroc Nitobond EP is a two-component epoxy bonding agent used to bond fresh, wet cementitious repair mortars and toppings to existing cementitious surfaces — particularly where the substrate is likely to remain permanently damp or wet, or where a moisture barrier between the substrate and the repair is required. It is suitable for internal and external applications. In balcony waterproofing and remediation contexts, Nitobond EP is most relevant at the concrete repair stage — applied to the prepared concrete substrate before application of Renderoc or similar cementitious repair mortars on spalled, deteriorated, or delaminated balcony slab soffit and edge areas. It is not a pre-membrane primer in the same sense as acrylic or bitumen primers — it is a bonding agent for cementitious-to-cementitious repair applications. Nitobond EP is the recommended alternative to Nitobond HAR where the substrate is wet or likely to remain permanently damp — HAR is for normal conditions, EP for wet conditions. The primer must be applied in a tacky state and the repair mortar must be applied before the primer becomes dry or fully cured — do not allow Nitobond EP to dry before applying the cementitious repair mortar.