Various research projects and the long-term use of laminated, finger-jointed window scantlings confirm their excellent suitability as products for window construction.
As part of the AUSTROKANTEL PLUS research project, Holzforschung Austria and FH-Bern conducted strength and stiffness tests to create a characteristic performance profile for window scantlings. In the course of the investigations considerably higher strengths for AUSTRKANTEL PLUS window scantlings could be proven, whereby a more economical dimensioning of windows becomes possible, which is particularly with larger dimensions of enormous advantage.
High-performance profiles for wood window and facade construction (2002 - 2005)
One research focus of Holzforschung Austria was the development of high-performance profiles for wood window and façade construction. Within the framework of the Competence Centre Wood Technology, the suitability of new wood species combinations for window scantlings was researched. Resistant wood species such as robinia, modified wood (thermowood,...) or oak, walnut and birch are used. In addition to the bonding quality and the durability, various surface treatments were also part of the research work. The suitability of different wood species combinations could be proven.
Bonding of surfaces with different surface conditions or pretreatments (1999 - 2000)
In addition to spruce wood, larch, Oregon pine and oak are frequently used in Austria for the production of scantlings. According to the technical guidelines of the Austrokantel association "Massive, finger-jointed and laminated profiles for wooden windows", proof of suitability is required for wood species that are difficult to glue.
Especially with oak wood there are often problems with the gluing quality, with the usual PVAc gluing systems a durable gluing is difficult to achieve. The aim of the project work of Holzforschung Austria was therefore to find solutions with PVAc adhesives for satisfactory gluing with unchanged technology and usual pressing time.
Different solutions were investigated in the project work. The adhesives themselves were modified by the addition of urea resin or hardener and crosslinker systems were added to the glue.
For the permanent bonding of oak wood, it was found that this can be achieved with PVAc adhesives and monomeric isocyanate crosslinkers. For the bonding of oak and spruce it was shown that this is possible with PVAc adhesives and isocyanate crosslinkers or also with salt curing adhesives.
Finger-jointed spruce window scantlings (1991 - 1994)
Holzforschung Austria and ift Rosenheim jointly carried out the research project "Finger-jointed spruce window scantlings". The aim was to prove the suitability of finger-jointed spruce window scantlings for window construction.
In 3 project sections (inventory, quality research, outdoor weathering) the influencing factors glue type, annual ring position, wood moisture difference, tine type and surface coating were investigated. After evaluating a total of several million individual data, the sufficient quality of finger-jointing of solid wood cross sections and laminated finger-jointed scantlings could be demonstrated.
The present research project confirmed that "finger-jointed spruce window scantlings" are ideally suited for window construction if the valid processing guidelines are adhered to.
Laminated wooden window profiles (1986)
In the mid-1980s the use of laminated profiles in window construction was investigated by ift-Rosenheim in a project work.
It was proven that all types of wood that are suitable for solid wood cross-sections can also be used for laminated cross-sections. The cross-sectional shape of the raw scantling can be rectangular or already adapted to the future window profile shape. From the results of the research project, the first "Guideline for the Lamination of Profiles for Wooden Windows" was developed.
Holzforschung Austria, DI (FH) Karin Hauer
Institute for Window Technology, Dr. Moarkas