When you’re fitting a new floor, selecting the right underlay is just as crucial as picking the flooring itself. This often-forgotten layer dramatically improves comfort, extends the life of your floor, and can even boost your home’s energy efficiency.
This guide will walk you through the essentials, helping you make a tailored, informed decision for your home.
Jump to a Section
- Why Underlay is so Important (It’s the Unsung Hero!)
- Checking Your Subfloor: Concrete vs. Timber
- Key Factors When Choosing Your Underlay
- Choosing Underlay by Flooring Type
- The Benefits of Investing in the Right Underlay
- General Underlayment Questions
- Installation and Subfloor Questions
- Technical and Performance Questions
- Flooring-Specific Underlayment
Why Underlay is so Important (It’s the Unsung Hero!)
The underlay is the vital cushion between your subfloor (the base, like concrete or timber) and your visible floor covering. Its critical roles include:
- Cushioning: Adding a soft, luxurious feel underfoot.
- Insulation: Providing thermal insulation to keep rooms warmer.
- Moisture Protection: Creating a barrier against dampness rising from the subfloor.
- Noise Reduction: Minimising the clatter of footsteps and sound transfer.
Checking Your Subfloor: Concrete vs. Timber
Your subfloor material is the first thing to check, as it dictates the underlay you must choose:
- Concrete Subfloor: You must use an underlay with a DPM (Damp Proof Membrane) built-in. This is vital to stop moisture rising from the concrete and damaging your new floor.
- Timber/Wooden Subfloor: Damp is less of a concern here, so you can focus more on soundproofing and cushioning, particularly important in upstairs rooms.
Key Factors When Choosing Your Underlay
| Factor | What to Consider |
| Thickness | Generally, a thicker underlay offers better comfort and noise reduction. However, some floating floors (like laminate) perform best with a medium-thickness to prevent movement or “bouncing.” |
| Moisture Resistance | Always choose an underlay with an integrated DPM for ground floors or any room with a concrete base. This prevents damp and mould. |
| Soundproofing | Look for high-density foam or rubber underlays if you want to minimise noise, especially in flats or between floors. |
| Thermal Properties | If you have underfloor heating (UFH), you need a thin, low-tog rated underlay that allows the heat to pass through efficiently. |
Choosing Underlay by Flooring Type
The best underlay is always one designed for your specific floor covering.
1. Underlay for Wood and Laminate Floors
Wood and laminate are known as ‘floating floors’ because they aren’t fixed to the subfloor.
- Laminate Underlay: Opt for a good foam underlay which often includes a moisture barrier. Medium density is ideal to prevent the joins from stressing.
- Engineered Wood Underlay: A rubber or high-density foam underlay is often recommended. These offer better stability and a high level of sound absorption, protecting your investment.
2. Underlay for Carpet
Carpet underlay is all about comfort and durability.
- Materials:Rubber crumb (durable for heavy traffic) or PU (polyurethane) foam (softer, lighter, and the most common choice today).
- Impact: A new, high-quality carpet underlay will make even an old carpet feel softer and can extend the life of your carpet by years. Look for high tog ratings for excellent thermal insulation.
3. Underlay for Click Vinyl and LVT (Luxury Vinyl Tile)
Click vinyl flooring is usually thinner and more rigid than wood or laminate.
- Dedicated LVT Underlay: Because LVT is thin, it needs a specific, high-density, low-profile underlay to prevent it from flexing, which can damage the locking mechanism. Standard thick foam underlay is usually not suitable.
- ⭐ Special Note on Protek Flooring: It’s a fantastic money-saving choice because many of their click-together luxury vinyl tile (LVT) products come with a built-in underlay already attached to the base of the plank. This saves you the cost and hassle of buying and fitting a separate underlay!
The Benefits of Investing in the Right Underlay
Choosing a quality underlay is a small investment that delivers huge returns:
- Reduced Noise: Creates a quiet, peaceful home environment.
- Warmth: Improves thermal insulation, helping to reduce heating bills.
- Protection: Guards your floor against wear, impact, and moisture damage.
- Luxury: Gives a plush, premium feel to every step.
Ready to upgrade your floors?Explore a wide collection of underlays for all flooring types, ensuring you find the perfect match for your subfloor and chosen material.
electing the correct underlay is a critical step for a long-lasting, comfortable, and quiet floor. Here are 20 frequently asked questions to help guide your choice:
General Underlayment Questions
- What is the primary function of flooring underlay?
- It’s a foundational layer that provides cushioning, thermal and acoustic insulation, moisture protection, and helps smooth out minor subfloor imperfections.
- Is underlay always necessary?
- For most floating floors (like laminate and engineered wood), yes, it’s highly recommended. Some vinyl planks (LVP) or floors with a thick, integrated pad may not require a separate underlay. Always check the flooring manufacturer’s warranty and instructions.
- What is a ‘floating floor’ and why does it need underlay?
- A floating floor is one that is not glued or nailed directly to the subfloor. Underlay provides the essential cushioning, joint support, and noise/moisture protection for these floors as they expand and contract.
- How does underlay affect the comfort of my floor?
- Underlay provides a luxurious, soft feel underfoot and absorbs the impact of footsteps, reducing strain on your joints.
- How long does underlay last?
- A good quality underlay can last the entire lifespan of the flooring it supports, often 15 to 25 years, depending on the material and traffic.
Installation and Subfloor Questions
- What is the difference between a subfloor and an underlay?
- The subfloor is the structural layer (concrete, plywood, OSB) that forms the base of the room. The underlay is the thin layer laid on top of the subfloor, right beneath the final floor covering.
- What is a DPM, and why is it important for a concrete subfloor?
- A DPM (Damp Proof Membrane) is a moisture or vapor barrier. It is vital over concrete to prevent residual moisture from rising up, damaging the floor covering, and leading to mold or mildew.
- Do I need a DPM for a timber/wooden subfloor?
- Generally, no, unless the timber is in a high-moisture area like a ground-floor extension or near a damp source. Timber subfloors are less prone to rising damp than concrete.
- Can I lay new underlay over old underlay?
- No, never. This is called ‘doubling up’ or ‘stacking’ and can create too much movement, causing the joints of your new floor to flex, unlock, or even break, often voiding the warranty.
- Does underlay help level an uneven subfloor?
- It helps with very minor imperfections, but underlay is not a substitute for subfloor preparation. You must level major dips or bumps with a levelling compound or plywood before installing the underlay.
Technical and Performance Questions
- How thick should my underlay be?
- The thickness depends on the flooring type. For laminate/wood, 3mm is a common standard to balance comfort and stability. For carpet, thicker options like 10mm or 12mm are popular for maximum luxury.
- What does the ‘tog rating’ on underlay mean?
- The tog rating measures the underlay’s thermal insulation. A higher tog is better for keeping rooms warm (less heat escaping).
- What kind of underlay is best for underfloor heating (UFH)?
- You need an underlay with a low tog rating (typically or less) to allow the heat to efficiently pass through to the room.
- Which materials are best for soundproofing?
- High-density materials like crumb rubber or dense cork underlays are highly effective at reducing both impact noise (footsteps) and airborne sound transfer.
- What is ‘impact sound’ versus ‘airborne sound’?
- Impact sound is the noise created by a direct force, like footsteps or an object dropping. Airborne sound is noise that travels through the air, like voices or music.
Flooring-Specific Underlayment
- What is the best underlay for laminate flooring?
- High-density foam or rubber underlays with an integrated DPM (especially for ground floors) are popular. The manufacturer’s recommendation is always the top choice.
- Do I need underlay for luxury vinyl tiles (LVT) or planks (LVP)?
- It depends on the product. Many click-fit LVT/LVP products have a pre-attached pad and do not need any additional underlay. Check the specific product instructions.
- What type of underlay is suitable for solid hardwood flooring?
- Solid wood is often nailed or glued down, but a denser material like felt or cork roll may be used in some floating solid wood applications for sound dampening.
- What is a “3-in-1” or “2-in-1” underlay?
- These are multi-function products. A “3-in-1” often includes a cushioning layer, a vapor barrier (DPM), and an adhesive strip for easy joining.
- Can I use carpet underlay beneath laminate or wood flooring?
- No. Carpet underlay is typically too soft and thick, which can cause excessive movement, leading to damage or breaking of the locking mechanisms on laminate or wood planks. You must use a firmer, dense underlay specific to hard flooring.
