You’ve chosen your perfect laminate planks, measured the room twice, and you’re ready to start laying your new floor. But wait—what goes underneath? The right laminate flooring underlayment can mean the difference between a floor that feels solid and quiet for decades and one that creaks, telegraphs every footstep, or fails within a few years due to moisture damage.
Underlayment is the unsung hero of any laminate installation. It cushions the floor, absorbs sound, levels minor subfloor imperfections, and—most importantly in Australian climates—provides a critical moisture barrier. Whether you’re renovating a Queenslander with timber subfloors or laying laminate over a concrete slab in a modern apartment, choosing and installing the correct laminate flooring underlayment will protect your investment and deliver the comfort and performance you expect.
What’s in this guide
- What is laminate flooring underlayment?
- Types of laminate flooring underlayment
- Choosing the right underlayment for your project
- Installation tips and best practices
- Common mistakes to avoid
- FAQ
What is laminate flooring underlayment?
Laminate flooring underlayment is a thin layer of material installed between your subfloor (whether concrete, plywood, or particleboard) and the laminate planks themselves. Unlike carpet underlay or tile adhesive, laminate underlayment serves multiple purposes simultaneously: it provides cushioning and support for the floating floor system, dampens footfall noise, smooths minor surface irregularities, and—critically—acts as a vapour barrier to prevent moisture from the subfloor migrating up into your laminate.
In Australia, most laminate manufacturers void their warranty if you skip underlayment or use an incorrect type. The Australian Building Codes Board also sets moisture-control requirements for flooring installations, particularly over concrete slabs, which makes a proper moisture-barrier underlayment essential in many projects.
Underlayment typically ranges from 2 mm to 6 mm thick. Thicker isn’t always better—excessive cushioning can stress the locking joints of your laminate planks and cause them to separate over time. Most manufacturers specify a maximum underlayment thickness (usually 3–4 mm) to maintain structural integrity.
Types of laminate flooring underlayment
Not all underlayment is created equal. Here are the main types you’ll encounter in Australian hardware stores and flooring suppliers:
Foam underlayment
Polyethylene or polypropylene foam is the most affordable and widely used option. Standard foam underlayment costs between $1.50 and $4 per square metre and provides basic cushioning and sound dampening. Many budget foam products include an integrated polyethylene moisture barrier film on one side, which is adequate for installations over dry timber subfloors. However, foam alone offers limited acoustic performance and minimal impact insulation—expect to hear footsteps clearly in rooms below.
Cork underlayment
Cork is a premium natural material prized for its excellent acoustic and thermal insulation properties. At $8–$15 per square metre, cork underlayment significantly reduces both impact noise (footfalls) and airborne sound transmission. It’s environmentally sustainable, naturally antimicrobial, and provides a firmer, more supportive feel underfoot than foam. Cork is ideal for apartments, upper-storey rooms, or homes where noise control is a priority. You’ll need to pair cork with a separate polyethylene moisture barrier if installing over concrete.
Rubber underlayment
Recycled or synthetic rubber underlayment offers the best sound and vibration dampening available, making it the top choice for multi-storey buildings and commercial applications. Expect to pay $10–$18 per square metre. Rubber is dense, durable, and resilient, but it’s overkill for most single-storey residential projects unless you have specific acoustic requirements or a home theatre.
Combination (all-in-one) underlayment
These products combine foam or cork with an integrated moisture barrier and sometimes an additional acoustic layer. All-in-one underlayments simplify installation (no need to lay separate poly film) and typically cost $5–$10 per square metre. They’re a smart middle-ground option for DIYers who want moisture protection and decent sound performance without the complexity of layering multiple products.
Attached underlayment
Some laminate planks come with underlayment pre-attached to the back of each board. This is convenient and ensures compatibility, but you lose the flexibility to choose a higher-performance underlayment. If your laminate has attached underlay, confirm it includes an adequate moisture barrier—if not, you may still need to lay polyethylene film over concrete subfloors.
Choosing the right underlayment for your project
Your choice of laminate flooring underlayment should be driven by your subfloor type, room location, budget, and performance priorities.
Subfloor considerations
Concrete slabs are common in Australian homes built after 1980. Concrete is porous and can release significant moisture vapour, even years after pouring. Always use an underlayment with a built-in moisture barrier (minimum 200 microns polyethylene) or lay a separate damp-proof membrane (DPM) before your underlayment. Overlap seams by at least 200 mm and tape them with waterproof tape.
Timber subfloors (common in older homes and Queenslanders) are less prone to moisture issues but can be uneven. A slightly thicker underlayment (3–4 mm) will help smooth minor dips and gaps between boards. Ensure the timber is dry, structurally sound, and free of rot before installing your underlayment.
Acoustic performance
If your laminate floor is going upstairs, in an apartment, or above a living area, invest in underlayment with a high Impact Insulation Class (IIC) rating. Cork and rubber products typically score IIC 60–70, which is excellent for residential use. Cheap foam usually sits around IIC 45–50, meaning footsteps and furniture movement will be audible below.
Thermal insulation and underfloor heating
If you’re installing underfloor heating, choose a low-tog underlayment (ideally <1.0 tog) to allow efficient heat transfer. Cork and thick foam can insulate too well, reducing heating performance and wasting energy. Many manufacturers now offer specific "heating-compatible" underlayments that balance moisture protection, acoustics, and thermal conductivity.
Warranty and manufacturer requirements
Check your laminate manufacturer’s installation guide. Most brands specify compatible underlayment types and thicknesses. Using an unapproved product can void your warranty, even if the floor performs well initially. When in doubt, buy underlayment from the same supplier or stick to products explicitly endorsed in the installation manual.
For practical advice on maintaining your laminate once it’s down, see our guide on washing laminate flooring and our tips for choosing the right laminate flooring cleaner.
Installation tips and best practices
Proper installation of laminate flooring underlayment is straightforward but requires attention to detail. Here’s how to get it right.
Prepare the subfloor
Your subfloor must be clean, dry, and level within 3 mm over a 3-metre span. Sweep and vacuum thoroughly—any grit or debris will telegraph through the underlayment and create noise or wear points. Fill cracks and low spots in concrete with a self-levelling compound. Sand down high spots on timber subfloors.
Lay the moisture barrier (if required)
If your underlayment doesn’t have an integrated moisture barrier and you’re installing over concrete, roll out 200-micron (or thicker) polyethylene film across the entire floor. Overlap seams by at least 200 mm and run the film 50 mm up the wall on all sides. Tape seams with waterproof duct tape or DPM tape. This step is non-negotiable in most of Australia—the Australian Bureau of Statistics data shows concrete slab construction is prevalent, and moisture-related flooring failures remain a leading warranty claim.
Roll out the underlayment
Unroll your underlayment perpendicular to the direction you plan to lay the laminate planks (this helps prevent seams from aligning). Butt seams tightly together but don’t overlap—overlapping creates a ridge that will telegraph through the floor. If your underlayment has a moisture barrier on one side, lay it with the barrier facing down (toward the subfloor). Tape seams with the manufacturer’s recommended tape, usually a foil or acrylic tape.
Trim and fit around obstacles
Use a utility knife to trim underlayment neatly around door frames, pipes, and vents. Leave a small gap (5–10 mm) at walls to allow for expansion—this gap will be hidden by your skirting boards. Don’t let underlayment bunch up or wrinkle; smooth it flat as you go.
Install laminate immediately
Once underlayment is down, start laying your laminate planks straight away. Underlayment left exposed can shift, tear, or collect dust. Work section by section if needed, rolling out underlayment just ahead of your plank installation.
Common mistakes to avoid
Even experienced DIYers can stumble when installing laminate flooring underlayment. Here are the pitfalls to watch for:
Using underlayment that’s too thick: Exceeding the manufacturer’s recommended thickness stresses the locking joints and can cause planks to separate or crack. Stick to 3 mm or whatever your laminate manual specifies.
Skipping the moisture barrier: If you’re installing over concrete without a moisture barrier, you’re almost guaranteed problems—warping, cupping, mould, or adhesive failure. Don’t skip this step to save $50; it’s a false economy.
Overlapping underlayment seams: Overlaps create bumps that show through the laminate and can cause uneven wear. Butt seams together tightly and tape them flat.
Ignoring subfloor prep: No amount of premium underlayment will fix a dirty, uneven, or damp subfloor. Invest time in prep work—it’s 80% of a successful installation.
Mixing incompatible products: Layering multiple types of underlayment or pairing cork with a non-breathable moisture barrier can trap moisture or create excessive softness. Follow system recommendations from one manufacturer.
Not acclimating materials: Store both your laminate planks and underlayment in the room where they’ll be installed for at least 48 hours before starting. This allows materials to adjust to temperature and humidity, reducing expansion and contraction issues later.
FAQ
Do I need underlayment if my laminate has it attached?
Usually not for the cushioning and sound dampening—the attached layer handles that. However, if you’re installing over concrete, you still need a separate moisture barrier (polyethylene film) unless the manufacturer’s specifications confirm the attached underlayment includes an adequate vapour barrier. Check the product data sheet to be sure.
Can I reuse old underlayment?
It’s not recommended. Used underlayment is often compressed, torn, or contaminated with adhesive residue and dust. It won’t provide the performance or moisture protection your new laminate needs. Underlayment is inexpensive relative to the total project cost—buy new.
How much does laminate flooring underlayment cost in Australia?
Basic foam underlayment runs $1.50–$4 per square metre. Mid-range combination products cost $5–$10 per square metre. Premium cork or rubber underlayment ranges from $8–$18 per square metre. For a standard 20 m² room, budget $30–$360 for underlayment depending on your choice. Remember to add the cost of moisture barrier film ($0.50–$1 per m²) and tape if not included.
What’s the best underlayment for a concrete slab?
Look for a combination underlayment with an integrated moisture barrier rated at least 200 microns. Products like Roberts Super Felt or Dunlop’s range with built-in DPM are popular in Australia. Alternatively, pair a quality foam or cork underlayment with a separate polyethylene moisture barrier for maximum flexibility.
Will thicker underlayment make my floor quieter?
Not necessarily. Acoustic performance depends more on material density and composition than thickness. A 3 mm cork or rubber underlayment will outperform a 5 mm cheap foam in sound dampening. Check the IIC rating rather than just thickness when comparing products.
Installing the right laminate flooring underlayment sets the foundation for a floor that looks great, feels solid, and lasts for years. Take time to match your underlayment to your subfloor type, moisture conditions, and acoustic needs, and don’t cut corners on moisture protection. With careful prep and the right materials, your laminate installation will deliver the performance and comfort Australian homeowners expect. If you’re exploring other flooring options, our guides on waterproof laminate flooring and floating timber flooring can help you compare alternatives.
Comparing quotes? Once you have 2-3 in hand, drop them into our free Renovation Quote Comparator to see totals side-by-side and catch the common red flags automatically.
Related guides
For more on Australian renovation costs, see: