Everything you need to know about flooring underlay

Flooring underlay

What is flooring underlay?

Flooring underlay – sometimes called underlayment – is a layer of material such as rubber, foam or felt inserted between the subfloor and your chosen flooring option (see diagram below.) There are various advantages to underlay which will be discussed further below.

Flooring Underlay

Choosing the right underlay for your home depends on a range of considerations. These are listed below:

  • The National Construction Code
  • Strata management and/or council requirements
  • Flooring type
  • Structure of the subfloor
  • Ceiling height
  • Installation method
  • Guidelines from the flooring and underlay manufacturers
  • The intended purpose of the flooring underlay

Why use flooring underlay?

Flooring underlay plays an important role in the safety and comfort of your home. One of the main reasons to use underlay is noise reduction, which is good for you and your neighbours. Whilst there are many reasons for using underlay, we explore some key factors below.

Reduction in sound

One of the biggest benefits of hard floor underlay is that impact sounds are significantly reduced. The loudness and sharpness of footstep sounds are deadened as the underlay acts as a cushion. An underlay reduces and mellows sounds and absorbs the ‘squeaking’ of the floating wooden floor, for example.

Using underlay on a hard floor above the ground floor is beneficial because it adds mass to the flooring. This reduces the amount of airborne noise travelling from the bottom floor upward and vice versa.

Fitting issues need to be considered to optimise impact and airborne sound reduction. Floating floors are preferred to options such as nailing your flooring to a sub floor, rigidly coupling the flooring to the sub floor and decreasing the difference your underlay could make.

Improvement in air quality

People spend about 90% of their time indoors, according to The Departments of Agriculture, Water and the Environment. This means we need to consider indoor air quality, just as we measure the pollution outside. Indoor air quality can negatively impact your health, comfort and performance.

Poor indoor air quality is caused by having volatile organic compounds (VOCs) in the home. These chemicals, which often have an odour, contain carbon that evaporates into the atmosphere at room temperature. VOCs are in a wide range of household products and construction materials, including glues and adhesives.

In 1998 the CSIRO estimated that poor indoor air quality costs the Australian economy over $12 billion annually. So, for your home, choose the best underlay to suit the conditions of your flooring and subflooring.

Moisture protection

It’s important that the integrity of the subfloor and the top and bottom of the new flooring is maintained. We care for the tops of our floors with polyurethane or oils, and need to install a moisture-proof membrane in between the top and the subfloor. Which underlay you choose will depend upon your installation plans and whether the subfloor is concrete or wood. Be aware that a moisture barrier and underlay are not the same thing, however you can purchase products that combine the two requirements.

In the Australian climate, mould growth needs to be monitored due to our sometimes prolonged periods of humidity. Avoid mould growth by having the most effective insulation from moisture.

Smoothing out imperfections of the subfloor

A subfloor needs to be flat, solid, level and stable. Use of the right underlay can immediately improve the appearance and function of the subfloor.

Temperature regulation

Just like the insulation in your roof and walls, great underlay will help your home maintain an even temperature throughout the year.

Safety when using underfloor heating

Underlay is required for wooden floors with radiant heating. If you are planning to have underfloor heating, speak to our expert team about the types of flooring and underlay you can choose from.

Scandi Interior Design

Types of flooring underlay

There are various types of underlays available for timber floor applications. Here at Back to Timber, the most commonly used types are Rubber and Foam. In general, for floating installations, any underlay can be used, but for gluing down we use only Rubber underlays. There is ongoing research into environmentally-conscious, recycled underlay options, and we’re monitoring that closely at Back to Timber.

There are two standard types of underlay we use:
Rubber or rubber waffle underlay is springy, durable and, because of its cellular construction, breathable. A high-quality option, it is often considered to be superior to other types of underlay.
Foam underlay was originally introduced as an inexpensive alternative to rubber. However, foam technology has improved to the point where this is not necessarily the case anymore.

There used to also be the option of felt underlays. It is the cheapest type of underlay and is made from wool and other fabrics. Rarely used today, felt used to be the only type of underlay available.


Flooring underlay experts

Here at Back to Timber, we can guide and assist you through the process of selecting flooring and underlay to suit your needs. As you’ve read, there are a technical factors to consider when choosing the perfect pair. Take a look at our underlay range below and contact us or visit one of our showrooms if you have any questions.

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