Description
ARDEX K 65 is an advanced fibre-reinforced smoothing and levelling compound for internal use, featuring Microtec technology. It is designed to rapidly smooth and level new and existing substrates prior to applying a floor finish, and unlike most levelling compounds it is formulated to be applied over timber. It can normally be walked on after approximately 2 hours at 23 degrees C. Manufactured by ARDEX Australia.
The fibre reinforcement is the reason it works over timber: timber substrates move, and an unreinforced cementitious topping cracks when they do. That, plus the low-VOC formulation and same-day walkability, is what makes it the standard choice for levelling a timber floor before carpet, vinyl or LVT. Also written ARDEX K65.
Technical Specifications
| Product type | Single-part, fibre-reinforced smoothing and levelling compound (Microtec) |
|---|---|
| Use | Internal only |
| Application thickness | 3-20 mm in one application; to 50 mm with 2-5 mm washed and dried aggregate |
| Mixing ratio | 4.8-5.0 litres of water per 20 kg |
| Mixing time | 2-3 minutes with a mixing paddle and heavy-duty drill (650 rpm) |
| Working time | Do not rework after 10 minutes |
| Walkability | Approximately 2 hours after application at 23 degrees C |
| Ready for floorcoverings | 24 hours for carpet; 48 hours for vinyl, at 23 degrees C |
| Compressive strength | Approx. 10 MPa (1 day), 20 MPa (7 days), 30 MPa (28 days) |
| Tensile bending strength | Approx. 5 MPa (1 day), 8 MPa (7 days), 10 MPa (28 days) |
| Bulk density | Approx. 1.2 kg/L |
| Fresh mortar weight | Approx. 1.8 kg/L |
| Coverage | Approx. 1.4 kg per square metre per mm – approx. 4.5 m² per bag at 3 mm |
| Packaging | 20 kg paper sack with polyethylene liner |
| Shelf life | 12 months in dry conditions, unopened, at 23 degrees C and 50% relative humidity |
Coverage Rates
ARDEX quotes approximately 4.5 square metres from one 20 kg bag at 3 mm thickness. On that basis:
| Thickness | Coverage per 20 kg bag |
|---|---|
| 3 mm (minimum) | Approx. 4.5 m² |
| 5 mm | Approx. 2.7 m² |
| 10 mm | Approx. 1.35 m² |
| 15 mm | Approx. 0.9 m² |
| 20 mm (maximum unaggregated) | Approx. 0.68 m² |
Coverage assumes a flat, level surface. Allow additional material where the surface is rough or uneven.
Where to Use
- New and existing strip timber floors
- Particleboard and plywood subfloors
- Concrete subfloors
- Compressed fibre cement flooring, terrazzo, quarry and ceramic tiles
- Concrete subfloors with electric underfloor heating, commissioned to AS 1884
- Lightweight autoclave concrete – contact ARDEX Technical Services first
Suitable floor coverings include carpet, vinyl, LVT, carpet tiles and floating floors.
How to Apply
- Prepare the subfloor – it must be solid, clean and free of dust, plaster droppings, grease, paint, oil, polish and any loosely adhered or water-softenable material. On timber floors, re-nail and firmly fix all loose boards before levelling.
- Prime – use ARDEX P 51 over standard concrete, mixed 1 part primer to 2 parts water and applied evenly with a push broom. Do not leave bare spots and brush off puddles. Allow to dry to a thin, clear film (minimum 3 hours, maximum 24 hours). Very absorbent concrete may need two coats. Use ARDEX P 82 or ARDEX P 9 on particle board.
- Mix – add the 20 kg bag to 4.8-5.0 litres of water while mixing thoroughly with a paddle and heavy-duty drill (650 rpm) for 2 to 3 minutes. Do not overwater. Concrete mixers and hand mixing are not suitable.
- Place – pour onto the prepared subfloor and spread with an ARDEX stand-up spreader or hand trowel, using a gauging tool with height adjustment to obtain an even thickness. Wear rubber or nylon studs to avoid leaving marks. Do not rework after 10 minutes.
- Build up if required – additional layers may be applied once the previous layer is dry. Above 20 mm, mix with 2-5 mm washed and dried aggregate to a maximum of 50 mm.
- Wait before covering – walkable from around 2 hours; carpet and floating floors after 24 hours; direct-stick vinyl after 48 hours.
Important Notes
- ARDEX K 65 is not suitable for the installation of direct-stick timber flooring. Floating floors and direct-stick timber flooring are not suitable substrates.
- Internal use only.
- Plywood and flooring-grade non moisture-resistant chipboard should have backs and edges sealed, be at least 18 mm thick, and be screwed or ring nailed to joists at 300 mm centres or less.
- Existing tongue and groove boards of traditional construction should be screwed or ring nailed down to the joists to give a rigidly fixed, flat, adequately braced surface. Remove any existing polish, wax or old adhesive first.
- Where underfloor heating is present, the system must be commissioned to AS 1884, then turned down to 15 degrees C before the compound and floor covering are installed, and re-commissioned gradually afterwards to avoid thermal shock.
- Low subfloor temperatures or high ambient humidity extend primer drying times. Do not install levelling compound until primers have dried thoroughly.
- Store in dry conditions in unopened packaging; shelf life is 12 months at 23 degrees C and 50% relative humidity.
Frequently Asked Questions
How long before you can walk on ARDEX K 65?
Approximately 2 hours after application at 23 degrees C. Conventionally laid carpet and floating floors can be installed after 24 hours, and direct-stick applications such as vinyl after 48 hours. All figures assume 23 degrees C and 50% relative humidity; drying also depends on installation thickness, floor covering type and site conditions.
Can ARDEX K 65 be used over particleboard?
Yes – particleboard is a listed substrate, along with strip timber, plywood, concrete, compressed fibre cement flooring, terrazzo, and quarry and ceramic tiles. Some brands of particleboard and chipboard carry wax coatings and sealers which must be removed mechanically, for example by sanding, before priming with ARDEX P 82 or ARDEX P 9. ARDEX P 9 can be applied directly to particle board but should not be used on strip timber.
How much ARDEX K 65 do I need?
Approximately 1.4 kg per square metre per millimetre of thickness. ARDEX quotes approximately 4.5 square metres from one 20 kg bag at 3 mm. That assumes a flat, level surface – allow additional material where the substrate is rough or uneven.
