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U is for Underlay

What is Underlay?


Underlay is a layer of material installed underneath your floor covering. As with selecting a carpet, choosing the right underlay can be an important decision and one that will help your new carpet perform it’s best for many years to come.

Why do I need Underlay?


Underlay is a key factor in carpeting, and there are many reasons why it is needed. The key reasons are that firstly it acts as a shock absorber to reduce the wear on your new carpet helping it to last longer, and secondly it is a requirement of both British Standards 5325 (2001) and manufacturers guidelines that underlay is used, and replaced when a new carpet is installed.

Some of the other reasons why underlay is important are:

  1. Underlay will add extra comfort underfoot to a new carpet.
  2. It can reduce the noise in a room and noise transference.
  3. It can help with heat retention and even save a little on your heating bills.
  4. It will improve the longevity of your new carpet, by up to 50%.
  5. It can make cleaning your new carpet easier.
What are Underlays made from?


There are several different types of underlay on the market, the most common ones are:  

  • Polyurethane

This is the new generation of underlays and is also known as PU or PU Foam.  As the name implies these are made up of a polyurethane foam which is usually from recycled pieces.  These are lighter in weight than traditional underlays but perform exceptionally well and often have excellent noise and heat insulation values.

  • Sponge Rubber

The more traditional material for underlays, although usually now made from a synthetic rubber rather than a natural rubber, these are still a popular choice and suitable for all areas.  They are considered a durable type of underlay and an excellent all rounder.

  • Felt

Felt underlays have a great level of comfort and are often made from natural materials, usually wool, and as such have reasonable noise and heat insulation values.  They are often cheaper than other types of underlay, however they can flatten over time and don’t recover well.

  • Crumb Rubber

Different to a sponge rubber these types of underlay are made from a densely packed crumbed rubber.  Often made from recycled materials they are able to withstand indentations better than most underlays.

  • Combination Underlay

Usually a combination of a crumb rubber base with a felt top these underlays offer the best of both material types and are often recommended by the manufacturers of woven carpets.


So which underlay is the right one? 


There can be several factors in deciding the right underlay for your carpet.  Each underlay performs better in different scenarios and therefore saying, for example, a polyurethane is ‘best all round’ isn’t true (albeit they do tend to be the most popular choice and can often work very well). Sometimes a more specialist underlay is required for unique situations, and we cover a range of scenarios here:

Underlay and the different areas of your home
If you are carpeting your whole house in a single carpet then choosing an underlay that can go under all areas makes sense so that each room has a consistent feel to it.  However you may decide to go for something more bouncy in the bedrooms to offer a higher level of comfort, while the lounge and stairways have something far more durable.  This is usually down to personal preference but sometimes other factors may lead us to advise you to use a particular underlay (such as sub-floor or carpet choice). 

Underlay and Stairs
When fitting underlay to stairs one would generally use a 9mm thick underlay. This is because the Gripperrods are suited to 9mm deep underlays, and using a deeper underlay can cause safety issues.  If a deeper underlay is required, then specialist Gripperrod is advised. 

Underlay and Underfloor Heating
With underfloor heating the aim is to keep the TOG rating of both the carpet and underlay to a minimum to allow the heating to work with minimal resistance.  Using a specialist underlay will help with this, as they are designed to be of a low TOG rating.  Be warned though, a lot of these underlays are often thinner and therefore not as comfortable underfoot.

Underlay and Wheelchairs
If a wheelchair is used in the area to be carpeted, then particular types of underlay are required which allow for what is called a ‘double stick’ installation. This is where the underlay is stuck to the floor and the carpet is then stuck to the underlay. Standard underlay with its usual installation would not be appropriate here because the force of the wheels would cause the carpet to distort and pull off the Gripperrods and underlay.


At Grimley Flooring we stock a wide range of underlays and are happy to discuss the options and provide samples in your home. Call now to arrange your free consultation and let us take the stress out of replacing your floor covering by guiding you through the right combination of products for your home.

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