Our Guide to Understanding Carpet Underlay

So, you’ve taken the plunge and decided to re-carpet your home. The perfect carpet has been picked out, the room’s been measured and you’re ready to go — but what about underlay?

From why it’s an essential component to how to choose the best underlay for your individual rooms, to why a new underlay is essential to getting the best out of your new carpet. Here’s our guide to understanding carpet underlay.

What is Underlay and why is it important?

Put simply, underlay is the padded material that’s placed underneath carpets before they’re laid. It has numerous purposes and is an essential part of carpeting a room.

Underlay isn’t just crucial for comfort underfoot, but it also drastically helps maintain your carpet as well as providing extra protection against moisture. It is also a great shock absorber, meaning it’s ideal for reducing noise from things like footsteps or moving furniture.

In general, new carpets without new underlay have a much shorter lifespan and are more at risk of rapid wear and tear. Underlay is especially important if you’re planning on laying carpet over concrete as it will help make walking across the room much more comfortable.

Aside from the obvious comfort benefits, UK carpet underlay manufacturer Ball & Young, have shared some lesser known benefits; Many people don’t know that good quality underlay can actually save you money, with a reduction in heat loss resulting in lower energy bills. Furthermore, underlay can play a role in reducing noise transfer, which results in an overall reduction of noise levels. Underlay is also critical in protecting the carpet pile, which in turn, makes cleaning easier and leaves your home more hygienic.

In short, if you’re looking for longevity, luxury feel and want your carpet to last, always ensure your carpet is fitted with a quality, new underlay underneath – carpets fitted without underlay may also invalidate your guarantee or warranty, so it’s a wise investment long-term.

Should I use old underlay?

Your carpet will need firm and consistent support to sustain maximum performance. Fitting old underlay will reduce the life of the carpet as it won’t provide the right support, resulting in wear showing quicker. It will also affect your wear guarantee.

What are the different types of underlay?

Yes, just like carpets, underlay comes in a range of different types. These include:

Foam underlay – Typically made of PU foam, this is one of the most versatile types of underlay. It’s soft and lightweight as well as being good for insulation and noise reduction. Foam is also a very easy underlay to fit, making it fantastic for difficult areas like staircases or hallways.

Sponge rubber underlay – Sponge rubber underlay is very durable and great for sound reduction which makes it one of the best carpet underlays for concrete floors. It’s also the best carpet underlay for underfloor heating as it allows heat from the underfloor panels to escape into the room efficiently.

Felt underlay – This is a more traditional form of underlay that provides excellent cushioning as well as a reasonable level of noise reduction and warmth. Felt underlays are typically made of wool, making them cheaper and easier to lay.

Crumb rubber underlay — This form of underlay is made mostly from recyclable materials that are densely packed together. It’s great for rooms with heavy furnishings as it will protect your carpet from indentations.

Should you use different types of underlay for specific purposes?

Which type of underlay you choose will be determined by several factors such as:

1. The type of carpet you’re placing on top

Your choice of carpet won’t have a huge amount of influence on the type of underlay you need. However, if you’ve opted for a carpet with a shorter pile height, you may want to add depth by choosing a slightly thicker underlay. This will provide extra cushioning without compromising on the style of your carpet.

Alternatively consider a thicker underlay for bedrooms, to create a really sumptuous deep pile effect underfoot.

2.  The type of floor it will sit on

Is your carpet going on top of a concrete floor or perhaps in a room with underfloor heating? These factors will determine the type of underlay you choose as you’ll want to go for one that provides the correct level of insulation, soundproofing and shock absorbency.

Sponge rubber or PU underlay is a great option for harder floors as it’s hard-wearing and provides plenty of insulation if the floor is made of a cold material like concrete.

3.  Which room you’re placing it in

You should try to choose the correct underlay to suit the purpose of the room if possible. Are you re-carpeting a bedroom or are you re-doing the carpet on your staircase? You’ll want an underlay that’s good at insulating and cuts out noise for the former, while the latter requires an underlay that’s versatile and easy to install on difficult surfaces.

Furnishings will also affect your underlay choice as you’ll want to protect your carpet from becoming permanently indented by heavy items. Denser underlays like Ball and Young’s Cloud 9 range are ideal for this.

When it comes to furnishing your home, the underlay you opt for can be just as important as your choice of carpet. It’s crucial that you understand all your individual requirements and make the right decision as doing so can really benefit your carpet and your home in the long run.

What are Tog Ratings?

Just like duvets, carpets and underlay also have tog levels which refer to their ability to retain heat. Typically, the higher the tog rating on your underlay, the better it will be at insulating your floor. If you opt for, or already have underfloor heating, be sure to add the tog rating and the carpet together to get a combined rating – especially if you’ve got the luxury of underfloor heating, or if you’re thinking of investing in it. You should be looking for a combined tog rating of less than 2.5 for your carpet and underlay for underfloor systems to operate efficiently. To find out more about our carpets and what tog ratings they hold, click here.

Which is the most environmentally friendly type of underlay?

Crumb rubber underlay — This form of underlay is made mostly from recyclable materials that are densely packed together.

What is the minimum thickness of underlay you recommend for a domestic household?

If you’ve opted for a thinner carpet, you may want to choose a slightly thicker underlay. Popular manufacturers make underlay of around 11mm-12mm and this is ideal. Although for more difficult areas like stairs, a 9mm underlay would be far easier to fit, rather than something as much as 12mm. 

Which is the best type of underlay to use for contract use?

Foam underlay – Typically made of PU foam, this is one of the most versatile types of underlay. It’s soft and lightweight as well as being good for insulation and noise reduction. Underlay manufacturers like Ball & Young have specific underlays suited for contract locations.

Which underlay is best for people who suffer from allergies?

This all depends on what you are allergic to, for example, if you are allergic to wool, don't opt for an underlay such as felt. Instead, use one that is made from other materials, such as foam underlay, which is made from PU foam.