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Underlay for Laminate Flooring? What’s Essential and What’s a Waste of Money?

There is a huge surge of consumers opting to install laminate flooring as a more cost effective substitute for real wood flooring. And along with that come a large number of questions on how to install the product so that it survives all of life’s abuse.

We have all heard our neighbour’s stories about a floor gone bad. The boards have shifted and ugly gaps have appeared between planks. Water gets into the seams and causes the floor to swell and delaminate, and the annoyance of the hollow clicking of the floor following you into the basement. Well selecting the right laminate underlay might go a long way in solving some of these issues.

First it is important to understand what the purpose is of laminate underlayment. It is really designed to even out the minor imperfection of the sub-floor so no one spot on the laminate floor is taking excessive pressure. Most laminate floors are made from medium density fiberboard (MDF), and as such can only take so much pressure before the fibers breakdown. Thus, the underlayment acts as a cushion. This is its first and foremost responsibility.

A good underlay supports the floor so as not to put too much undue pressure on the click, interlocking system!

Secondary to that the laminate underlay acts to dampen the noise of daily traffic. I found this particularly obvious with my dog in the house and his late night pacing. Industry has responded with product and a testing method called Impact Sound Transmission testing. It uses a multi headed hammer to tap on a floor and then measures sound transmission to the floor below. It is called an IIC rating. A rating of over 55 is required to pass current building regulations for multi level housing. The higher the rating the more noise it blocks.

In addition to noise transmission from walking on the floor, industry has moved to create an underlayment that will reduce the noise that is airborne from radios, TVs etc. The testing procedure for this is referred to as a Sound Transmission Class (STC). A rating of over 51 is commercially acceptable. Again the higher the rating the more noise it stops.

It used to be that the only way that you could get a laminate underlay that offered these sound dampening advantages was to go to a cork or rubber commercial underlay adding more that a dollar per square foot to the cost of your flooring. Today industry has created a range of foam underlay products that attain these commercial rating at a much lower cost making it a more reasonable choice for residential applications.

The last real issue, although there are many more trivial features like R value and antimicrobial additives, is the need to have a vapour barrier. Moisture is a laminate floor’s worst enemy. If moisture penetrates into the MDF core it destroys the accuracy of the interlocking joint. This is after all only a bunch of dust particles compressed into a plank. If water migrates up from the slap into the floor the joints will not be able to hold the flooring together. Thus on concrete sub-floors it is always essential to lay a vapour barrier first. Some manufacturers have now begun to laminate a polyethylene film to the foam underlay.

So lets go back to the original question. What is the best laminate floor underlay? It depends! If all you need is an underlay that will cushion your floor, buy the basic roll of foam for less the twenty cents a foot. If you are at all concerned with sound transmission into your basement then check out the list of noise reduction laminate underlay and their ratings on our website.

If you are laying a laminate floor on a cement slab inquire about a number of products that have a built in vapour barrier laminated to the back of the foam underlay. This offers a 2-in-1 installation for little added cost. Check out the list of more sophisticated designs that include a built in overlap for more effective moisture protection.

For further information on laminate floor underlayment, the various brands, their sound transmission ratings and vapour barrier designs visit our website at