Self-levelling screed systems — balcony waterproofing

System Description

ARDEX K 301 is ARDEX Australia's confirmed external self-levelling resurfacing and smoothing compound — the only self-levelling compound in the ARDEX Australian range specifically confirmed for external use on balconies, patios, courtyards, domestic driveways, and garages. Unlike ARDEX K 15 Microtec (which is internal only), K 301 is formulated to resist UV, rain, heat, cold, and the moisture cycling conditions of exposed external concrete surfaces. In balcony waterproofing remediation, K 301 serves a specific pre-membrane role: smoothing, resurfacing, and filling depressions on damaged, rough, or uneven concrete slabs before primer and waterproofing membrane are applied. It is not applied over a waterproofing membrane — the membrane always goes above K 301, not below. Applied from 2mm to 20mm in a single application. For thicknesses from 10–30mm, mix with an equal volume of 2–5mm aggregate — the aggregate reduces the self-levelling effect, which means minor falls (minimal grade) can be set into the surface with an aggregate mix. K 301 is not a falls correction screed for significant drainage gradients — for major falls correction, specify ARDEX A 38 or A 48. For external wet areas (balconies) where tiles will be applied, ARDEX confirms the sequence: K 301 → waterproofing membrane → tile adhesive → tiles. K 301 can also be left as an exposed wear surface on lightly trafficked external areas such as courtyards, footpaths, and domestic garages — in these applications no membrane or tile is required. Walkable after 2–3 hours at 20°C. Ready for tiling, waterproofing, or coating after 24 hours at 23°C / 50% RH. Ready for light rubber-wheeled traffic after 48 hours.

System Description

ARDEX LQ 92 is a cement-based self-levelling and self-smoothing compound for levelling uneven concrete floors prior to tiling. In external balcony applications, ARDEX specifically confirms that LQ 92 MUST be protected with a waterproofing membrane and tile finish installed above it — it cannot be used as an exposed external surface and is not a standalone external levelling compound in the same sense as ARDEX K 301. This is an important distinction: LQ 92 is appropriate for external balcony use only when the system sequence above it is confirmed — waterproofing membrane and tiles above, concrete substrate below. In this role it is a useful pre-membrane levelling compound for smoothing uneven balcony slabs to a thin, consistent surface before the waterproofing system is applied. Applied from a feather edge to 25mm in a single application. Greater thicknesses can be achieved with multiple layers or by adding aggregate to the mix. Not recommended for use under vinyl floor coverings. For large area levelling applications, ARDEX references K 301 and LQ 92 as the appropriate external products — not K 15 Microtec or other Ardurapid-based internal compounds. Applied as a pourable, free-flowing self-smoothing compound. Suitable for concrete substrates. Confirm primer type and minimum cure time before applying waterproofing primer and membrane above.

System Description

ARDEX K 15 Microtec is ARDEX Australia's primary internal rapid-drying self-levelling smoothing compound, using ARDEX Ardurapid technology for fast strength gain and drying — floor coverings can be installed in as little as 16–18 hours. It is microfibre reinforced for improved crack resistance and flexibility on internal subfloors. K 15 Microtec is listed here solely to clarify that it must not be used on external balconies. It is an internal product only. Ardurapid technology is not designed for UV exposure, external moisture cycling, or freeze-thaw conditions. Specifying K 15 on an external balcony — even under a waterproofing membrane — risks long-term compound failure as the Ardurapid binder is not formulated for permanently wet or UV-exposed conditions. For external balcony substrate preparation: use ARDEX K 301 or ARDEX LQ 92 (with membrane and tile above). For internal wet area substrate preparation: K 15 Microtec is appropriate.

System Description

Mapei Ultraplan Eco is Mapei Australia's ultra-fast hardening self-levelling smoothing compound for interior floor preparation — 1–10mm application depth, pot life 20–30 minutes, light foot traffic after 3 hours, floor coverings after 12 hours. EMICODE EC1 certified — very low VOC. Ultraplan Eco is listed here solely to clarify that it is for interior use only. The Mapei TDS confirms: interior levelling of new and existing substrates, as long as not subject to moisture. This explicitly excludes external balcony applications where moisture, UV, and drainage are standard conditions. The broader Mapei Ultraplan range — including Ultraplan, Ultraplan Maxi, Ultraplan Trade, and Ultraplan Contract — are all interior products. None of these should be specified on external balconies. For external balcony substrate preparation, confirm with Mapei Australia which products are approved for external pre-membrane use before specifying.