FAQ
What is floor underlay and why do I need it?
Floor underlay sits between your subfloor and finished flooring, providing essential functions that protect your investment and improve performance:
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Moisture protection - Creates a barrier preventing moisture transmission from concrete subfloors that could damage laminate or wood flooring.
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Acoustic insulation - Reduces sound transmission between floors, particularly important in flats or multi-storey homes.
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Cushioning and comfort - Provides slight give underfoot, making hard flooring more comfortable whilst protecting against minor subfloor imperfections.
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Thermal insulation - Improves heat retention and works with underfloor heating systems to enhance energy efficiency.
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Subfloor smoothing - Compensates for minor surface irregularities, preventing hollow spots and premature wear.
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Stability - Reduces lateral movement in floating floor installations, preventing shifting and extending floor life.
Most laminate, LVT and floating wood installations require underlay for warranty validation and optimal performance.
Can I reuse old underlay?
Reusing old floor underlay is not recommended. Previously installed underlay loses its cushioning properties through compression, particularly in high-traffic areas. Moisture barrier films may be damaged during floor removal, compromising their protective function. Acoustic performance degrades over time through material breakdown. Old underlay also retains dirt and moisture that could affect new flooring. Always install fresh underlay matched to your specific flooring type for optimal performance and warranty compliance.
Which rooms need specific underlay types?
Different rooms benefit from underlay with specific properties:
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Kitchens and bathrooms - These rooms require moisture barrier underlay. However, we don't recommend wood flooring in bathrooms due to moisture exposure; instead, luxury vinyl flooring offers a waterproof alternative.
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Living rooms and bedrooms - These rooms benefit from acoustic underlay for comfort and noise reduction.
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Hallways and dining rooms - These suit durable options that handle high traffic whilst providing sound insulation.
For underfloor heating in any room, choose thermal underlay like ThermaBase Vapour that conducts heat efficiently. Underfloor heating works well with laminate, LVT and engineered wood flooring when paired with an appropriate thermal underlay.
Which underlay do I need for laminate flooring?
Laminate flooring typically requires 2-3mm underlay for laminate with moisture barrier properties. Our 2mm options include Evergreen Silver Moisture Base for budget installations, SilentPro 2mm for enhanced acoustic performance, and ThermaBase Vapour 2mm for underfloor heating compatibility.
For 3mm thickness, Combat Green and Evergreen Green BarrierPro offer moisture protection with additional cushioning, whilst SilentPro Plus 3mm delivers superior sound dampening.
For comprehensive guidance on selecting laminate underlay, read our detailed underlay guide for laminate flooring. Complete your installation with laminate accessories, including scotia beading and door bars.
What underlay suits LVT flooring?
LVT flooring requires specialist underlay for LVT, depending on the installation method. Click-lock LVT uses a similar underlay to laminate flooring, with 2-3mm options that provide moisture protection and acoustic benefits. Whereas dryback LVT glued directly to subfloors benefits from our 1.8mm LVT Dryback Underlay, which creates a stable surface for adhesive whilst providing sound insulation.
Explore our full vinyl flooring collection and LVT accessories for complete installation solutions.
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Which underlay works for engineered wood flooring?
Engineered wood flooring performs well with 2-5mm underlay for engineered wood, depending on installation location and heating requirements. For standard installations, 2mm options like ThermaBase provide moisture protection and comfort. Underfloor heating installations benefit from ThermaBase Vapour 2mm with enhanced thermal conductivity.
Thicker 5mm options including FibreLux Fibreboard or XPS Polystyrene Foam suit ground floor installations requiring additional insulation. Premium 7mm FibreLux Fibreboard delivers maximum acoustic performance for flats or rooms above living spaces.
Complete your project with engineered wood accessories including trims and scotia beading.
Do I need underlay for solid wood flooring?
Solid wood underlay requirements depend on installation method. Secret-nailed solid wood flooring over wooden subfloors typically installs without underlay, with boards nailed directly through the tongue. Fully glued solid wood bonds directly to prepared concrete subfloors using specialist adhesives.
However, floating solid wood installations benefit from a 5-7mm fibreboard underlay that provides acoustic insulation and compensates for minor subfloor irregularities. FibreLux options work well for floating solid wood, offering stability whilst allowing slight floor movement. Browse solid wood accessories for complete installation requirements.
What underlay do I need for carpet?
Carpet underlay typically ranges from 7-12mm thickness and uses foam, rubber or felt materials designed to cushion foot traffic whilst supporting carpet fibres. Unlike hard flooring underlay that prioritises moisture barriers and thin profiles, carpet underlay focuses on comfort, durability and prolonging carpet life by absorbing impact.
Our underlay collection primarily serves hard flooring installations. For carpet-specific underlay recommendations, explore our dedicated carpet underlay range matched to your carpet type and room usage.
H2 – What thickness of underlay should I choose?
Floor underlay thickness affects comfort, acoustic performance and suitability:
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1.8mm - Specialist thin profile for dryback LVT installations requiring minimal height build-up whilst maintaining acoustic benefits.
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2mm - Standard thickness for laminate and click-lock LVT, balancing moisture protection, comfort and affordability.
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3mm - Enhanced cushioning for laminate installations prioritising comfort and acoustic performance in residential settings.
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5mm - Increased insulation and sound dampening for ground floors, engineered wood or areas requiring improved thermal properties.
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7mm - Maximum acoustic performance for flats, upper floors or anywhere sound transmission is a priority concern.
Thicker underlay provides better insulation and acoustics but increases floor height, which may affect door clearances and transitions.
How much is underlay?
Floor underlay costs range from £1.99/m² to £19.99/m² depending on specifications. Budget options provide basic protection for simple installations. Mid-range acoustic underlay balances performance and affordability. And premium thermal options are compatible with underfloor heating. Specialist underlay and professional installations can add to the cost. Calculate the total cost by multiplying your room area by the per-metre-squared price.
How much underlay do I need?
This depends on the size of your area. Calculate underlay requirements by measuring your room's length and width, then multiplying them to get the total square metres. Add 5-10% for cutting waste and fitting adjustments.
Our underlay comes in packs covering 6.5m² to 15m², depending on the product. For example, a 4m x 3m room (12m²) with 10% waste needs 13.2m², requiring one 15m² pack with minimal leftover. Larger projects may need multiple packs. Underlay typically runs perpendicular to your flooring direction, with joins taped rather than overlapped.
How to lay underlay for flooring?
Laying floor underlay follows a straightforward process. Start with a clean, dry, level subfloor free from debris. Roll out the underlay perpendicular to your planned flooring direction, with any moisture barrier film facing downward. Butt edges together without overlapping, using underlay tape to seal joins and prevent movement. Trim underlay to room edges using a utility knife, leaving no gaps at walls.
View our full range of accessories to complete your floor installation. Need help? Our nationwide floor fitting service handles subfloor preparation, underlay and floor laying.
Will you deliver my underlay?
Yes, we offer free UK delivery on qualifying orders and convenient click-and-collect from any of our 10 stores. Need help selecting the right underlay for your specific flooring type or room conditions? Contact our team for expert advice on matching underlay to your flooring installation.