Three-layer window board

Nowadays wooden windows are seldom made of solid timber. Due to modern technologies, wooden windows are made of so-called laminated board. Such production ensures timber defects elimination and preservation of its positive characteristics.
What are the main shortcomings of an ordinary wooden frame and how does it differ from the laminated window board?
Timber is a natural material and as all living things it gradually gets older and displays its shortcomings:

•  absorbs atmospheric humidity and vapor (swells);
•  when it dries out it warps and cracks.

It’s definitely pointless to install a double glazed unit into so an unsteady structure. Thus, specialists have found out how to restrict such ‘unsteadiness’ of  timber by using glued beams in manufacturing. Most defects of an ordinary wood window are removed within difficult production process.
At any timber crosscut one can see annual rings. If two boards are glued in such a way that their annual rings are attached at a certain angle, some fiber resistance appears (it seems as if boards back up each other). Only due to this a wooden structure doesn’t change it shape. If three boards are glued, the structure becomes even more solid. This process is used for wooden window manufacturing these days.
Timber elements are made of layers, by means of gluing two or three boards (lamellas). Lamellas are also glued of a few boards, which have undergone culling: removing knots, pitch pockets, cracks.
This multilayer timber won’t split as for its gluing adhesive of D4 standard is used. This adhesive firmly bonds elements penetrating into the texture of timber. The bonding is so secure that lamellas can also be joined lengthwise. Such window elements can bear load of 320 kg.
Of course, wooden windows made of glued laminated timber have higher strength and durability as compared to the usual ones made of solid bar. Glued timber ensures stability of the window to the weather conditions and prevents it deformation. Due to all these wooden windows again are gaining popularity, but unfortunately they are comparatively expensive too.