There are a number of different types of underlay for laminate and wood floors. Selecting the right kind for your particular situation is of great importance so we've put together this guide to assist you in making the correct choice.
Dreamwalk Heatflow Underlay has been designed specifically for use with underfloor heating systems and wood or laminate flooring. The underlay is 2mm thick with small holes punched through at regular intervals allowing the heat to rise and penetrate through. Also attached to the underfloor heating underlay is a plastic vapour barrier layer that prevents any moisture coming through to the wood or laminate flooring.
Polyfoam underlay is the cheapest, entry level underlay available but this does not mean that it is a poor option. So long as your project meets certain criteria, there is no reason why Polyfoam underlay should not be used and fulfill its purpose perfectly. Polyfoam underlay is usually white, approximately 2 mm thick and is intended for use on perfectly level, wooden sub-floors. It should not be used on concrete sub-floors.
If you have a concrete sub-floor and intend to install your flooring using the floating method then you will almost certainly want to use a foam underlay with a built in vapor barrier. This prevents moisture from the concrete sub-floor rising up into your flooring and causing problems related to expansion and movement. If you think about it, any floor that is to be installed using the nail down method i.e. onto a wooden sub-floor would compromise any vapor barrier properties of an underlay and so a regular foam or rubber underlay would be all that is required ensuring that any issues regarding damp and moisture are dealt with by other means.
We repeatedly stress the importance of preparing your sub-floor so that it is as flat and even as possible before laying your floor and as such, in theory, an underlay should never be used to account for unevenness in your sub-floor. However, we understand that in reality, this is not always possible and in some cases, so long as the imperfections are minimal i.e. no more than 2 mm in every meter, Fiberboard can be used to correct this slight unevenness. Fiberboard also has excellent sound reduction qualities which can be of great benefit if the room in question is above ground floor and has rooms or another property below. Fiberboard will also provide a degree of thermal insulation though bear in mind that a 2 mm expansion gap should be left between the staggered boards as well as a 10 mm gap around the perimeter of the room.
Made of green, high density sponge rubber, this underlay is a step up from Polyfoam underlay and will provide greater sound and thermal insulating properties. It is suitable for nail down and floating installations and though it could be used in conjunction with a damp proof membrane on concrete sub-floors, it would make more sense to use a rubber underlay with combined foil vapour barrier in these situations.
Rubber underlay with combined foil vapor barrier is ideal for laminate flooring and engineered floors that are to be installed using the floating method over concrete sub-floors. As mentioned above, it is pointless to use any underlay with a combined vapor barrier where the nail down method of installation is to be used as the nails will simply perforate the vapor barrier layer.