Underlay Guide
Underlay Guide: The Foundation of a Perfect Floor
Underlay is the hidden layer between your subfloor and your new flooring—but its impact is anything but hidden. The right underlay enhances comfort, reduces noise, improves insulation, and ensures your floor performs exactly as it should.
Choosing the correct underlay isn’t just a technical decision—it’s essential to achieving a flawless finish and long-lasting results.
What Does Underlay Do?
Underlay plays several important roles:
Stability
Creates a smooth, even base for your flooring
Comfort
Adds cushioning for a softer feel underfoot
Noise Reduction
Minimises sound from footsteps and movement
Insulation
Helps retain heat and improve energy efficiency
Protection
Shields flooring from moisture and subfloor imperfections
Without the right underlay, even the highest quality flooring won’t perform at its best.
Types of Underlay
Different materials are designed for different flooring types and environments. Here’s how to choose the right one:
Foam Underlay
A versatile and cost-effective option suitable for laminate and wood flooring.
- Comfortable underfoot
- Good sound absorption
- Compatible with underfloor heating
- Best used on non-concrete subfloors
Foam & Foil Underlay
An upgraded version of foam with added heat retention and moisture protection.
- Reflects heat back into the room
- Includes built-in damp proof membrane
- Ideal for concrete subfloors
Fibreboard Underlay
A premium option for wood and laminate floors.
- Smooths uneven subfloors
- High sound insulation
- Strong thermal performance
- Requires a damp proof membrane on concrete
Thermal Underlay
Designed for energy efficiency and underfloor heating systems.
- Excellent heat transfer performance
- Helps maintain consistent room temperature
- Provides moisture resistance
Choosing the Right Thickness
Underlay thickness typically ranges from 1.8mm to 7mm, but thicker isn’t always better.
- Underfloor heating: Use thinner underlay for efficient heat transfer
- Click-fit flooring: Keep underlay under 5mm to maintain locking strength
- Uneven floors: Slightly thicker options can help level minor imperfections
The key is balance—comfort, performance, and compatibility.
Damp Proof Membrane (DPM)
A damp proof membrane is essential when installing flooring over concrete.
It acts as a barrier to prevent moisture rising from the subfloor, protecting your flooring from:
- Warping
- Swelling
- Structural damage
Some underlays include a built-in DPM, offering a convenient all-in-one solution.
Understanding TOG Ratings
TOG (Thermal Overall Grade) measures how well an underlay insulates heat.
- Higher TOG: Better insulation, warmer rooms
- Lower TOG: Allows heat to pass through more easily
Guideline:
- Use low TOG with underfloor heating
Use higher TOG for better insulation without heating
Underlay & Underfloor Heating
If you’re installing underfloor heating, your underlay choice is critical.
Look for:
- Low TOG rating
- Thin profile
- Materials designed for heat transfer
The wrong underlay can block heat and reduce efficiency.
How to Choose the Right Underlay
Your ideal underlay depends on:
- Flooring type (laminate, wood, LVT, etc.)
- Subfloor (concrete or timber)
- Room use (high traffic, moisture exposure)
- Heating system (underfloor heating or not)
- Desired comfort & sound insulation
There’s no one-size-fits-all—getting it right ensures your flooring looks better, feels better, and lasts longer.
Need Expert Advice?
Choosing underlay can feel technical—but it doesn’t have to be.
Our flooring specialists are here to help you select the perfect option based on your flooring, subfloor, and lifestyle—so you get the best possible result from your investment.
