Ardex K 40 Flow High Flow Levelling & Smoothing Compound Grey 22kg

• Product ID: 38989
• Suitable For: levelling and smoothing a variety of new and existing subfloors
• Area of use: INT
• Application Method: trowel
• Volume: 22KG
• Container Type: bag
• Type: concrete
• Colour: grey
• Brand: Ardex
• Manufactuer: Ardex
• Box Size: 1

ARDEX K 40 FLOW is designed to level and smooth a variety of new and existing internal subfloors in a single application. It is compatible with concrete, cement/sand screeds, anhydrite screeds, stone, terrazzo, ceramic tiles, and suitable timber floors.

SUBSTRATE PREPARATION

The subfloor surface must be clean, sound, and free of dust, plaster debris, grease, polish, and any materials that are water-soluble or loosely adhered. Any adhesive residues present must be sound, hard, well adhered, and unaffected by water. Use an appropriate degreaser to eliminate any polish, wax, grease, oil, or other contaminants before proceeding. Direct-to-earth subfloors must have an effective damp proof membrane (DPM); if the DPM is missing or damaged, or if the substrate is damp, refer to the ARDEX DPM 1 C, ARDEX DPM 1 C R, or ARDEX MVS 95 datasheets for guidance.

PRIMING

All surfaces must be primed to maximize working time, maintain flow life, and prevent air bubbles from forming in the leveling compound. For cement/sand or gypsum screeds (check manufacturer recommendations before starting), mix 1 part ARDEX P 51 Primer with 3 parts water. For concrete subfloors, use 1 part ARDEX P 51 Primer to 2 parts water. Apply the primer neat on timber surfaces and allow to dry. Note: ARDEX K 40 FLOW can be applied at a maximum thickness of 6mm over gypsum or timber subfloors, but avoid using impregnated boards as they can hinder primer penetration. For smooth, dense, and non-absorbent subfloors like ARDEX Damp Proof Membranes and smooth power-floated concrete, use ARDEX P 4 Primer. ARDEX K 40 FLOW can be applied in very thin layers down to 2mm; however, for thin applications, ensure proper mixing with the correct water ratio and application on a properly primed substrate for optimal self-smoothing and finish.

MIXING

Use between 5¼ and 5½ liters of water per 22kg bag of ARDEX K 40 FLOW. For applications below 6mm, we recommend using the maximum water content. Add the powder to the specified amount of clean water in a clean mixing container and stir thoroughly until a lump-free mortar is achieved. Using an ARDEX mixing paddle with a slow-speed electric drill (600-1000 rpm) makes mixing easier.

APPLICATION

Pour the mixed ARDEX K 40 FLOW mortar onto the prepared subfloor and spread it using a steel finishing trowel or float. The excellent workability of ARDEX K 40 FLOW allows for easy troweling of fresh mixes into previously applied material within 30 minutes of application. For larger areas, consider pumping ARDEX K 40 FLOW. In domestic and light-duty installations, all chipboard must conform to the latest BS EN 312 standard and be of suitable flooring grade. The superior smoothing and leveling properties of ARDEX K 40 FLOW facilitate an exceptional finish with minimal effort. While spike rollers can be used if desired, they are not necessary as a quality finish is typically achieved with a gauging tool or trowel, depending on the application depth. Apply the product at temperatures above 5°C, noting that lower temperatures will extend the working time while higher temperatures will reduce it.

PUMPING

ARDEX K 40 FLOW may be pumped using appropriate floor screed mixer pump units. For guidance on pumping techniques and suitable equipment, please contact our Technical Support Department.

APPLICATIONS OVER UNDERFLOOR HEATING

The heated screed should be installed per BS 8204 Part 1 and BS EN 1264. The underfloor heating system must be commissioned according to the manufacturer’s instructions and relevant standards. Once commissioned and thermally cycled, turn the heating system down to room temperature, ensuring it does not drop below 15°C before installing ARDEX K 40 FLOW and the final floorcovering. Gradually bring the underfloor heating system up to its normal operating temperature to avoid rapid thermal shock.

TIMBER FLOORS

Plywood subfloors must be rigid, dry, and capable of supporting the anticipated loads as per BS 8203 for resilient flooring and BS 5385-3 for ceramic tiling. When installing ceramic tiles, seal the backs and edges of the plywood with a suitable material, such as polyurethane varnish. Before leveling wooden floors, securely fasten all loose boards. For sufficiently rigid but uneven or worn timber floors, pre-level them with ARDEX K 40 FLOW and allow it to dry before installing a minimum 6mm thick flooring-grade plywood or an appropriate tile backing board. Ensure adequate subfloor ventilation to prevent moisture movement and deterioration. ARDEX K 40 FLOW can be applied from 2mm to 20mm in a single application over properly conditioned and fixed flooring-grade plywood that is free from adhesion barriers. Tongue and groove floorboards must be at least 22mm thick. For smoothing these boards or timber floors in non-domestic areas, consider overlaying with plywood or refer to the ARDEX FA 20 datasheet. In domestic and light-duty applications, all chipboard must meet the latest BS EN 312 standard. Ensure all boards are securely fastened according to the manufacturer’s guidelines and avoid installing ARDEX K 40 FLOW on floating chipboard floors or those over water-fed underfloor heating systems due to potential cracking over joints from moisture or thermal movement. For thin smoothing layers, consult the ARDEX FEATHER FINISH datasheet, and sand and vacuum the chipboard thoroughly to remove any adhesion barriers before priming with undiluted ARDEX P 51 Primer. Note: If the ARDEX P 51 Primer does not absorb into the board surface, achieving adhesion may not be possible; check with the board supplier if unsure. The maximum application thickness is 6mm.

THICKNESS

ARDEX K 40 FLOW can be applied in thicknesses ranging from 2mm to a maximum of 20mm in a single application. A minimum thickness of 3mm is recommended for non-absorbent subfloors when an absorbent layer is required by the flooring adhesive. For thicknesses over 10mm, consider using ARDEX K 40 HB, which can be applied up to 40mm.

DRYING AND HARDENING

ARDEX K 40 FLOW is walkable after 2 hours, and layers up to 5mm can receive floorcoverings after about 6 hours at 20°C. Layers up to 10mm thick will dry in approximately 12 hours, while applications from 10mm to 20mm require about 24 hours to dry, depending on site conditions. Ceramic tiles and non-moisture-sensitive natural stone can be installed as soon as the ARDEX K 40 FLOW is walkable; however, for moisture-sensitive natural stone installations, allow at least 24 hours before laying. If the mortar is subjected to rapid drying conditions or if the floorcovering installation is delayed for more than 48 hours, protect the surface to prevent damage and contamination.