Residential wall-to-wall carpet
Stretch-fit installation | Resilient recycled polyester or wool-blend felt with good recovery and a stable surface. | 7–10 mm | 80–150 kg/m³ | Comfort, cushioning, improved impact-noise absorption and protection of the carpet backing. | Use a dry product. In moisture-prone slabs, install a tested vapour-control layer beneath the complete flooring system. | Lay tightly butted sheets or rolls; keep seams away from heavy traffic lines. Do not create ridges beneath the carpet. | Check compression set, recovery after loading, roll flatness, odour, fibre shedding and compatibility with the carpet backing. |
Residential carpet
Direct glue-down installation | Low-profile, dimensionally stable felt specifically approved for adhesive bonding. | 3–6 mm | 100–180 kg/m³ | Controlled cushioning without excessive movement, adhesive failure or telegraphing through the carpet. | Substrate moisture must comply with the adhesive and flooring manufacturer’s limits. | Use only compatible adhesive and primer systems. Follow open-time, rolling and curing requirements. | Request adhesive-bond testing, peel-strength data, dimensional stability and a statement on plasticiser or solvent compatibility. |
Luxury vinyl tile or plank
Floating click installation | Very firm, thin felt or fibre underlay approved for the specific click-lock system. | 1–2 mm | 180–300 kg/m³ | High dimensional stability and low deflection to protect joints from excessive movement. | Use a separate vapour barrier where required by the flooring system and slab conditions. | Do not use soft, thick felt unless the flooring supplier expressly permits it. Stagger or butt joints according to the installation instructions. | Verify residual indentation, compressive strength, joint-load performance, plasticiser migration and approval for the exact LVT construction. |
Laminate flooring
Floating installation over concrete | Dense, thin synthetic felt or fibre underlay with integrated or compatible vapour-control protection. | 2–3 mm | 150–250 kg/m³ | Support for click joints, reduction of minor impact noise and limited correction of small surface irregularities. | Concrete installations commonly require a continuous vapour-control layer; confirm the required vapour resistance for the project. | Subfloor must be clean, dry and sufficiently flat. Do not rely on underlay to correct major level differences. | Check compressive strength, creep resistance, thickness tolerance, joint durability and compatibility with the laminate locking profile. |
Engineered timber flooring
Floating installation | Firm, low-compression felt or fibre underlay suitable for timber flooring. | 2–4 mm | 160–280 kg/m³ | Balanced acoustic improvement, dimensional support and protection against excessive vertical movement. | Manage slab moisture before installation. A vapour-control layer may be required over mineral substrates. | Maintain the specified expansion gap. Avoid underlay that permits rocking, joint opening or excessive board deflection. | Confirm compatibility with the timber board thickness, locking system, underfloor heating and the required acoustic assembly. |
Solid timber flooring
Secret-nail or staple installation | Stable, moderate-thickness felt used only where approved by the flooring and installation system. | 3–6 mm | 120–220 kg/m³ | Reduction of minor contact noise without interfering with fastener penetration or board stability. | Subfloor moisture and timber moisture must be controlled before installation. | Use a compatible structural subfloor. Do not place compressible felt where it can reduce fastener holding strength or create movement. | Check nail or staple penetration, compression under point loads, dimensional stability and approval for the selected fixing method. |
Floating cork flooring
Residential dry areas | Thin, firm felt or fibre layer compatible with cork’s inherent resilience. | 1.5–3 mm | 150–260 kg/m³ | Support of the click system while preserving cork’s comfort and thermal properties. | Use moisture protection where required by the subfloor and flooring construction. Avoid wet-area applications unless specifically approved. | Keep the substrate flat and clean. Prevent overlapping seams and localised soft spots. | Verify indentation resistance, thermal resistance, compatibility with cork finishes and suitability for radiant-heating systems. |
Commercial carpet tile
Loose-lay or releasable installation | Very firm, thin, dimensionally stable felt only when permitted by the carpet-tile system. | 1–3 mm | 180–320 kg/m³ | Traffic stability, reduced tile movement and controlled rolling-load performance. | Subfloor moisture must meet the flooring and adhesive requirements; avoid trapped moisture under releasable systems. | Use a smooth, clean and level substrate. Confirm whether the system requires full contact, tackifier or no adhesive. | Request castor-chair testing, rolling-load performance, dimensional change, seam behaviour and clean-removal data. |
High-traffic hospitality or office carpet
Stretch-fit installation | High-density, resilient felt with enhanced wear resistance and low permanent compression. | 6–9 mm | 120–200 kg/m³ | Long-term comfort retention, traffic-load recovery and improved protection of the carpet backing. | Control moisture during construction and operation; use a vapour-control strategy where the substrate requires it. | Use professional seam preparation and tensioning. Avoid excessive thickness in areas with doors, transitions or wheeled equipment. | Check residual compression after cyclic loading, castor-chair compatibility, fire classification and cleaning-chemical resistance. |
Underfloor heating system
Timber, laminate or carpet finish | Low-thermal-resistance felt with stable compression behaviour and documented heating-system compatibility. | 1.5–3 mm | 180–300 kg/m³ | Efficient heat transfer while maintaining dimensional support and avoiding overheating at the floor surface. | Moisture control remains essential, especially over concrete. Follow the flooring system’s commissioning procedure. | Keep the combined thermal resistance of flooring and underlay within the heating-system limit; avoid thick, highly insulating felt. | Request thermal-resistance values in m²·K/W, thickness tolerance, temperature ageing data and approval for the specified heating type. |
Concrete or mineral subfloor
New construction and renovation | Felt underlay selected together with a vapour-control layer, rather than used as a substitute for moisture management. | Application-dependent | Application-dependent | Stable installation over a clean, flat and sufficiently dry base. | Measure subfloor moisture using the method specified for the region and flooring system. Do not cover a wet slab without an approved solution. | Repair cracks and high spots before laying underlay. Maintain continuous protection at perimeter and penetrations where required. | Check moisture-test method, vapour resistance, alkaline resistance, compatibility with primers and tolerance to residual construction moisture. |
Areas with demanding acoustic targets
Multi-family and hospitality projects | Felt selected as part of a tested floor-ceiling or floor-wall assembly; density alone is not sufficient. | 3–10 mm | System-specific | Impact-sound improvement, airborne-sound control and reduced footfall transmission, subject to the complete assembly. | Moisture and vapour control must not compromise acoustic continuity or create a rigid bridge. | Install continuously and avoid gaps, compression points and rigid perimeter bridges. Follow the tested assembly exactly. | Request laboratory test reports, declared acoustic values, test floor construction, frequency range, field expectations and installation tolerances. |
