Free Shipping on Orders over £99

  • Review us on

    Trustpilot
  • Need Help? Call: 01803 416410

Orders placed before 12pm on weekdays will be sent out the same day. All other orders will be processed the next working day*.

15% OFF SELF ADHESIVE TILE EFFECT DOOR BARS WITH CODE "TA15"
laminate underlay

How to Choose & Fit Laminate Underlay: A DIY Guide

When you’re excited about installing a new laminate floor, it’s easy to focus solely on the stylish planks you’ve chosen. However, the secret to a professional, long lasting, and comfortable laminate floor is the layer you never see: the laminate underlay. This crucial component is often misunderstood, but getting it right is the difference between a floor that feels solid and quiet, and one that feels cheap, noisy, and wears out prematurely.

Choosing the correct laminate underlay and fitting it properly is an essential skill for any DIYer. It protects your investment, enhances your home’s comfort, and ensures your new floor performs at its best. This step by step guide for 2025 will walk you through everything you need to know, from understanding the different types available to the best installation practices for a flawless finish.

Jump to Section:

Why is Laminate Underlay Non-Negotiable?

Laminate flooring is installed as a ‘floating floor’, meaning the planks click together but aren’t fixed to the subfloor. Laminate underlay is a high performance sheet material that sits between the subfloor and the laminate, and it is absolutely essential for several reasons:

  • Supports the Click System: It provides a stable, slightly cushioned base that supports the interlocking joints of the laminate planks. This prevents them from flexing, creaking, or separating under the stress of foot traffic.
  • Sound Insulation: Laminate can be noisy. A quality underlay significantly reduces impact sound (the noise of footsteps travelling to rooms below) and dampens ambient sound within the room, making your home much quieter.
  • Thermal Insulation: It acts as an insulating barrier, helping your room feel warmer and preventing cold from rising from the subfloor, a significant benefit over concrete floors in UK homes.
  • Moisture Protection: Many underlays include a built in Damp Proof Membrane (DPM). This is vital for protecting the laminate’s HDF (High Density Fibreboard) core from moisture damage when installed on concrete ground floors.
  • Smooths Minor Imperfections: While not a fix for a very uneven floor, it can smooth out tiny bumps and texture in the subfloor, providing a better surface for the laminate to sit on.

Choosing the Right Laminate Underlay for Your Home

Selecting the right product is crucial. Here are the main types you’ll find in the UK and what to consider:

Types of Underlay:

  • PE Foam: A common and affordable option, usually 2-3mm thick. It’s lightweight and often comes with a silver or gold foil backing which acts as an integrated DPM, making it convenient for concrete subfloors.
  • Fibreboard: Comes in dense, rigid boards (typically 3mm, 5mm, or 7mm thick). It offers excellent thermal insulation and sound reduction, and is great for smoothing out slightly uneven wooden floorboards. It does not have a built in DPM, so a separate one is needed for concrete floors.
  • XPS Foam: Lightweight but rigid foam boards or fan fold sections. They provide a great balance of thermal and acoustic insulation and are good at levelling minor irregularities.
  • Sponge Rubber: A premium, dense option that offers superior durability and the best performance for impact sound reduction. Ideal for apartments or upstairs rooms.

Underlay Specification

  • Thickness: A common mistake is thinking thicker is always better. For laminate flooring, an underlay between 3mm and 5mm is usually the sweet spot. Using an underlay that is too thick and soft (like carpet underlay) will allow too much movement bounce and can damage the laminate’s click joints.
  • Tog Rating (Thermal Insulation): A higher Tog rating means better insulation. If you have underfloor heating (UFH), you must do the opposite and choose a specialist low Tog underlay (typically below 0.8 Tog) to allow heat to pass through efficiently.
  • Sound Reduction (dB Rating): If reducing noise is a priority (for example, in a flat or upstairs bedroom), look for an underlay with a high decibel (dB) rating (20dB or more is considered good).
  • Subfloor Type: For concrete subfloors in the UK, you must have a Damp Proof Membrane (DPM). This can be integrated into your underlay or laid as a separate sheet first.

Your Toolkit: Essential Tools & Materials for the Job

Having the right gear ready will make the process much smoother.

Tools:

  • Tape Measure & Pencil
  • Sharp Utility Knife or Stanley Knife (with plenty of spare blades)
  • Straight Edge or Ruler
  • Knee Pads & Gloves

Materials:

  • Your chosen Laminate Underlay
  • Damp Proof Membrane (DPM) if not built into the underlay
  • Underlay Tape or Strong Duct Tape

Preparation: The Foundation for a Perfect Laminate Floor

A professional finish starts with perfect preparation.

  • Clear the Room: Remove all furniture and old flooring.
  • Clean the Subfloor: Sweep and then vacuum the entire subfloor thoroughly. Remove any old staples, nails, or lumps of adhesive. The subfloor must be completely clean, dry, and free of debris.
  • Check for Level: Use a long straight edge or spirit level across the floor. The subfloor should be flat, with no deviations of more than 2-3mm over a 2 metre span. Significant dips should be filled with a self levelling compound, and high spots on concrete should be sanded down.
  • Prepare a Wooden Subfloor: Screw down any loose floorboards to stop them squeaking. If the boards are very uneven, it’s best to overlay them with flooring grade plywood (minimum 6mm) to create a smooth, flat surface.
  • Prepare a Concrete Subfloor: If you are not using an underlay with a built in DPM, now is the time to lay your separate DPM sheet. Roll it out to cover the entire floor, overlapping any seams by at least 20cm and taping them securely. Allow the DPM to run up the walls by a few centimetres.

How to Fit Laminate Underlay: A Step by Step Guide

With your room prepped, you’re ready to lay the underlay.

Step 1: Lay the First Section

Start in a corner and roll out your laminate underlay (or lay your first row of fibreboards). As a general rule, it’s best to lay the underlay in the same direction as you plan to lay your laminate planks. If your underlay has a DPM foil side, this usually faces down on concrete and up on wooden floors, but always check the specific instructions for your product.

Step 2: Cut the Underlay to Fit

Roll the underlay out until it reaches the far wall. It should be cut to fit snugly against the skirting boards or walls. Use your sharp utility knife and a straight edge for a clean, precise cut. For cutting around obstacles like radiator pipes, make small, neat cuts.

Step 3: Lay Subsequent Sections

Roll out your next piece of laminate underlay alongside the first. The most important thing is to make sure the edges of the two pieces butt up against each other perfectly. They should be touching snugly, with no gaps, but they must not overlap (unless the product has a specific self adhesive overlap strip). An overlap will create a hard ridge under your laminate flooring that you will feel underfoot.

Step 4: Tape the Seams

Once two pieces are butted together, run a line of underlay tape or strong duct tape along the entire length of the seam. This is a crucial step that stops the pieces from moving apart, prevents grit from getting between the joins, and creates a more stable, continuous layer for your laminate to sit on. If you’ve used a DPM, this also maintains the integrity of the moisture barrier. Continue this process until the entire floor is covered.

Common Mistakes to Avoid When Fitting Laminate Underlay

  • Overlapping Seams: This creates hard ridges that you will feel and can cause the laminate to sit unevenly.
  • Forgetting the DPM on Concrete: This is the number one cause of laminate flooring failure in the UK, leading to swelling and warping.
  • Using the Wrong Type: Using carpet underlay (too soft) or a high Tog underlay with UFH will cause major problems.
  • Not Taping Seams: This allows the underlay to shift and compromises any moisture or acoustic barrier.
  • A Dirty or Uneven Subfloor: Any debris or significant bumps left underneath will be felt through the final floor and can cause damage over time.

The Perfect Foundation for Your Laminate Flooring

Congratulations! By following these steps, you have now correctly fitted your laminate underlay and created the perfect foundation for your new floor. This professional level preparation will make your laminate feel more solid, last longer, and contribute to a warmer, quieter home. Taking the time to get this unseen layer right is a DIY job that pays dividends in comfort and quality for years to come, ensuring your final floor looks and feels absolutely fantastic.

Get Your Project Started

Choosing the right laminate underlay is the first step to a flawless finish. Whether you need superior sound insulation, underfloor heating compatibility, or a reliable moisture barrier for a concrete subfloor, we have the perfect solution for your UK home. Explore our range to find the ideal foundation for your project.

Shop Laminate Underlay

Related Blog Posts

Comments are closed.