Advantages of KVH® structural timber
- Dried structural timber components available in cross-sections of up to 14/26 cm
- Dimensionally stable because they are kiln-dried to 15 ± 3% and cut on a split-heart basis (free-of-heart on request)
- Two qualities available:
- planed for exposed areas (Si)
- leveled for non-exposed areas (NSi) - Meets higher requirements than those specified in grading standard DIN 4074-1
- Suitable for structural timber in timber frame buildings and timber house construction
- Minimum tender specification work because of a clear agreement on quality
- Resistant to insects thanks to kiln drying; preservative treatment can be dispensed with
- Economical preferred cross-sections and lengths of up to 13 m available for immediate delivery from stock; longer lengths available on request
Better than state-of-the-art
The requirements imposed on KVH® structural timber exceed the usual requirements set out in national grading regulations and are aimed at achieving not only reliable strength values but also a defined visual appearance. The maximum permitted moisture content of 18%, for example, is lower than the limits set out in most national product standards, while the definition of surface quality is both more stringent – if defined at all in the national regulations – and covers more criteria. Reference can be made to a European standard to find out how KVH® structural timber graded by strength in accordance with German grading regulations equates with the relevant European strength classes. Individual points are addressed in more detail below.
Kiln-dried and systematically cut
For modern timber buildings (residential buildings), a wood moisture content any higher than 18% is far from ideal and in some European countries it is no longer even permitted. KVH® structural timber is kiln-dried to a maximum moisture content of 15 ± 3%. When the finger-joints are made, the moisture content of every single piece of wood is checked.
Another special feature of KVH® structural timber is the method of cutting used. The square-sawn timber is cut on either a free-of-heart or split-heart basis, depending on the surface quality class. In split-heart cutting the log is sawn lengthwise along the ideal course of the pith, thereby minimizing the propensity for cracking. In free-of-heart cutting the heart plank, which is particularly susceptible to cracking, is also removed from the cross-section. This special method of cutting ensures that KVH® exhibits outstanding dimensional stability and has little propensity for twisting.
Strength graded in accordance with European regulations
KVH® structural timber is strength graded according to grading standard DIN 4074. This German grading standard complies with the requirements of the European standard EN 14081 for strength grading. In this regard the normal German grading class for KVH® structural timber, which is S10 TS, corresponds to European strength class C24 as defined in the European standard EN 1912.
Graded according to appearance
Depending on whether KVH® structural timber is to be used purely for its dimensional stability and low moisture content or whether a high-quality appearance is also desired, two different surface quality classes - KVH®-Si (exposed applications) and KVH®-NSi (non-exposed applications) - are available to choose from. For exposed applications there are certain limits set for such features as knot size, knot condition, ingrown bark and crack widths. The grading criteria are set out on site Requirements of KVH® structural timberRequirements to be met by KVH.
Both types are finger-jointed as a rule. The use of color-neutral adhesives means that the finger joints are barely visible. The look of the natural surface is preserved.
