What’s Down Under?
I play the bagpipes, so that question gets asked all the time but when it comes to what goes under the floor you choose, the answer is more important.
Whether you are laying Laminate, Bamboo, Cork or Timber there are several important factors that must be right.
Preparation of your sub floor is the first consideration. Renovators are frequently faced with different levels in the house caused by different old floor coverings. For example tiles in the Kitchen and Carpet in the Living area. Common sense dictates your new floor covers all these areas at the same height without ramps.
Companies are emerging that specialise in just preparing your sub floor. Alternatives include raising the lower levels with ply. Seek advice on what is best for your place.
The next challenge is to get the sub floor level. Manufacturers’ recommendations are that flooring be installed on a subfloor with variation in levelness (not smoothness) no greater than 3mm over a 3m span. Failure to do this will result in soft spots and possible creaking.
Low spots are filled with Ardit (think self levelling concrete) or Arditex (a latex based Ardit) to smooth any imperfections which would affect the installation and subsequent performance of the floor covering. The installer could also plane and sand the high spots of a timber subfloor to reduce the need for levelling compound.
Next comes an appropriate underlay. This provides a water barrier and a smooth surface to lay on. It can also add significant sound proofing. In recent months, the European Federation of Producers of Laminate Flooring (EPLF), the most recognised and respected body on laminate flooring in the world, released a technical bulletin regarding underlay specifications.
Of important note was a new “minimum benchmark” for moisture vapour transmission (the ability of subfloor borne moisture vapour to transmit through the underlay and into the underside of the flooring). The report in question specifies that all underlays should reach an SD Value ≥ 75. The higher the SD Value, the better the underlay is at blocking moisture vapour. This can eliminate the potential for cupping, peaking, noisy floors and excessive expansion as a result of rising moisture vapour from the subfloor.
By Guy Thornycroft