engineered/multilayer floors manufacturers and publication information

Contract Flooring Journal (CFJ)

Article by Terry Wolfe, Flooring Forensics. CFJ August 2008 Issue page 20 “Delamination: No need to split hairs”

“Over the past couple of years, I have encountered a new problem that I had not met previously. It is the delamination of engineered (multilayered) boards. This problem seems to occur in installations over underfloor heating (UFH) “

Contract Flooring Journal (CFJ)

Article by Peter Kaczmar, Trada CFJ July 2008 Issue pages 24 & 26 nb: Mr Kaczmar is an independent expert on wood flooring problems with Trada Timber Research & Development Association

“I was called out recently to several successive inspections to investigate the development of cracking within the wear layer of engineered wood strip flooring”

“the construction of the boards in all these cases was shown to consist of a hardwood wear layer bonded to a conventional 11 veneer plywood base, complete with balancing veneer. In each case though, the flooring was made by a different manufacturer”

“the floors were all installed into high value properties with underfloor heating and showed characteristic cracking and fissuring of the surface which extended through the full depth of the wear layer”

“the sheer consistency with which they occurred led me to believe that the problem was more systemic than circumstantial”

“the moisture and movement dynamics of, say a floor engineered with a core constructed from laminated softwood billets running counter to the direction of the grain of the wearlayer will be fundamentally different to one where the core consists of plywood which will therefore respond differently to changes in climatic condition”

“this is reflected in the above examples where the wearlayer consisted of a medium movement species and where the plywood base effectively holding it rigid, could not respond to, or accommodate, the natural movements of the wearlayer” “Consequently, any internal stresses created by natural shrinkage could not easily be dissipated, resulting in fissuring of the wearlayer”

Contract Flooring Journal (CFJ)

July 2008 Issue: Pages 24 & 26 Author: Peter Kaczmar, Timber Research & Development Association (Trada) Please refer to complete article attached.

Junckers

“Wood is a living material. Wood will contract when heated from an underfloor heating system and during the heating season larger gaps than normal will form between the boards”

Source: Junckers web site

Technical Advice Link K10.0 Engineered Flooring General Information

Underfloor Heating

Residential/Commercial KAHRS “Beech and Hard Maple multi layer floors expand and contract more than other wood species” “Underfloor heating causes the wood to dry out more, which results in additional shrinkage” “In a cold dry climate. (eg. Sweden), cracks between strips and slightly concave boards are to be expected”

Wooden Flooring Sale Website

Multi Top Floors

“In practice, Multi Top Floor XL flooring is almost certain to shrink when used with UFH, and there will be some movement of the floor. This is due to the relatively high moisture content; the solid wood wear layer is about 10% and the ply core about 14% when the planks come out of the factory, and these levels cannot be reduced in advance through re-kilning, for example, without affecting the integrity of the plywood” etc “After a months use with UFH, these levels can drop to 6-7%; this loss of moisture manifests itself as shrinkage. If the moisture loss is severe, there can also be a breakdown in the cellular structure of the wood, leading to splits in the wear layer”

“lively” species – hard, brittle woods such as Maple, Jatoba, and Larch tend to react by splitting and moving more readily. We recommend theses species are not used with UFH”

“The use of standard, micro-bevelled planks will minimise the visual impact or shrinkage”

Source: Multi Top website