Wood types for exterior components
Although there are no real technical reasons for it, demand for knotless timber now holds sway. Therefore, triple-laminated wooden window profiles are increasingly being used. These consist of three layers and have knotless top layers. From a technical point of view, such profiles are to be classed as equivalent to solid wood profiles. The following wood types have proved to be particularly suitable for window manufacture.
| Wood type | Origin | Colour | Property | Resistance class |
| Hemlock | USA Canada | Whitish grey to light greyish brown | Brittle, good stability | 4 |
| Pine | Europe | Heartwood reddish brown, sapwood light | Resinous, good stability as a laminated square section | 3-4 |
| Spruce | Europe | Light | Less resinous, good stability as a laminated square section | 4 |
| Larch | Europe | Heartwood reddish brown, darkens intensely, sapwood yellowish | Somewhat brittle, resinous, good stability as a laminated square section | 3-4 |
| Oregon pinie | USA Canada | Heartwood yellow to reddish brown, sapwood white | Resinous, good stability | 3 |
| Oak | Europe | Sapwood grey, heartwood greyish yellow to light brown | Hard, average stability | 2 |
| Meranti | South-East Asia | Sapwood grey, heartwood greyish yellow to light brown | Highly dependent on raw density, good stability | 2-4 |
| Teak | Burma Java | Heartwood golden brown, darkens later | Very good resistance, very good stability | 1 |