Carpet Padding (Underlay)

Cushion underlay to make carpet last
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Carpet Underlay - What to look for.

Carpet underlay can be called various things depending on where in the world you live. Carpet 'padding' or carpet 'cushion' is primarily used in the US, while the term 'underlay' is used in the UK. There are a few misconceptions about underlay, some people say that you must buy the most expensive underlay you can afford, while others don't think underlay is that important at all - so save your money! Well, neither view is correct. The truth is that carpet and underlay should compliment each other.

Carpet padding is one of those products that gets cheaper the more you buy - so some retailers will happily "recommend" you underlay that, while it might be cheap, doesn't necessarily offer you or your carpet the right option. Always make sure that your retailer can offer you a variety of underlay and also is able to explain the difference between them. This is always the sign of a good quality retailer.

What is Carpet Padding for?

Most carpet purchasers think that carpet underlay is simply to make the carpet feel softer underfoot. While this is one of the benefits, the main reason is to protect the carpet from premature wear. Underlay acts as a sort of shock absorber, absorbing foot traffic and allowing the fibers to bounce back rather than being trodden hard into the sub-floor surface. This has the effect of prolonging your carpet's life and in the long run, saving you money!

Buying (or being advised to buy) carpet underlay that is too thick is probably the most common mistake made buy carpet buyers. Underlay that is too thick has the effect of "stretching" the carpet fibers and causes premature wear. Also, carpet that sits higher than the recommended maximum of 7/16" will be harder to fix around the perimeter of the carpet.

What types of carpet underlay are there?

Rubber waffle underlay
Rubber Underlay for Carpets These days rubber waffle carpet padding is good quality and can be chosen with confidence that it won't break down and disintegrate like the underlay of old used to do. The construction includes an air space and is very soft underfoot. There are various thicknesses and weights, but generally the heavier the better.

Urethane underlay
Urethane and Bonded Urethane padding is constructed from waste products of old furniture, which is bonded to form a carpet underlay that has proved to be very popular with consumers today. It is measured by its density, in pounds per cubic foot and there is a recommended minimum density of around 5lbs. However, many carpet retailers will tell you that their minimum should be around 8lbs. Probably somewhere in between is more than adequate and will give you a good quality, long lasting underlay. Of course, always take into consideration the amount of traffic that your carpet will get.

Flat Rubber Underlay
flat rubber underlay Probably the best underlay you will find is flat rubber. Its availability really depends on where you live. You may have to do a bit of digging, but will the advent of the Internet you should be able to find it without too many problems. While this type of underlay is relatively expensive, you can be sure that it will last at least as long as your carpet. This type of underlay may even last longer than your carpet and not need replacing when your carpet does. However, my Mother's 30-year-old carpet with flat rubber underlay still looks pretty good, considering the wear it's had over the years!

Under floor heating
When you have or are considering under floor heating ( and who wouldn't!), you will need to consider a different type of underlay, one specifically designed for the purpose. You want one that will not absorb too much heat. This resistance to heat flow is measured in "togs*" and the lower the value the better for under floor heating purposes. Tog values less than 1 are recommended to compliment under floor heating systems.

Flooring Fact


For those that need to know! - A "tog" is a measure of resistance to heat flow through a material. 1 tog = 0.1mēK/W. For example, your bedding duvet (quilt) may be rated "6 tog", while your shirt may be "0.7 tog"

The table below shows examples of floor finishes and their Tog values, taken from BS EN 1274.

Tog ValueThermal ResistanceTypical Examples
0.0 0.00 mē K/W Ceramics, stone, slate, marble
0.5 0.05 mē K/W Synthetic blocks, linoleum, laminates
1.0 0.10 mē K/W Carpets, underlays, 13mm hardwood, parquet
1.5 0.15 mē K/W Deep pile carpets, 22mm hardwoods and laminates

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