Whether the element is open or closed at the top is determined by the area of application. If, for example, the element is to be filled with fill on site as a storey ceiling or roof terrace (LIGNO Rippe Q3-x), its cavities are open at the top (feature _r0). To guide pipes at the top of the element, a cross grid (_r25, _r50) can be added to some superstructures. For roof superstructures, there is usually a flat closed finish _rg0 (LIGNO Block Q-x, LIGNO Block Q3-x or corresponding versions of LIGNO Akustik klassik).
Wooden roof panel
dampens noise level
Industrial noise reduced by 6 dB
The client of this first commercial project carried out with LIGNO® Acoustics is a specialist in the production of airbag fabrics. The company operates production sites around the world, some of which are noisy. An essential requirement is therefore the effective attenuation of noise levels - as was the case with the new construction of this hall for the expansion of the site in Murg.
The various solutions used to reduce noise levels in the company's previous halls were not completely satisfactory. In some cases, acoustic ceilings had to be retrofitted under conventional sheet metal roofs at great expense and effort.
Wood for statics and acoustics
For the new building, the planners went a new way with the timber construction company and the manufacturer Lignotrend: the load-bearing roof panel was to take over the acoustic task at the same time. This was made possible by a cross-laminated timber rib element in which an absorber was inserted between the ribs and which was provided with joints in the soffit.
Statically, these cross laminated timber elements can also take on slab forces. Connected directly to the upper chords of the steel trusses, they also take on the stiffening effect instead of diagonal braces or wood-based panels.
In laboratory tests on the acoustic effectiveness, wood fibre rather than mineral wool proved to be the most efficient absorber. 3000 m² of roof surface made of LIGNO® Akustik Q klassik thus reduce the interior sound level in the hall by up to 6 dB instead of the required 3 dB, so that even the hearing protection for the workers could be reduced. The aW value of the construction is 0.55.
Based on this first object, the Lignotrend acoustic elements were further developed: Today there are several profiles (e.g. a fine strip look), knotty wood types for modern design, with absorption values aW of up to 0.80.
Sound insulation to the outside
The building authorities also required a high level of sound insulation to the outside.
A RW value of 50 dB was achieved.
In terms of installation time, the cross-laminated timber solution is in no way inferior to the trapezoidal steel sheeting: it took 2½ days to close the pane, and the sealing was carried out parallel to the installation so that the elements were not exposed to the weather.
The acoustically effective roof pane provides a working environment in the BST hall that promotes concentrated work with a higher quality of quiet and thus also the quality of work and ultimately occupational safety. The employees also feel more comfortable in the hall with the "wooden roof" for purely visual reasons.
LIGNO® Acoustic Q classic | Roof componentProduct code:LIGNO® Akustik Q klassik_Q3_150-210_rg0_s0_k50l_p0_al40g_625-95-30_WTL_gb_b0
_rg0 Closed, without crossgrid
The height of the load-bearing webs of the element is variable and determined according to static requirements from load and span. Within the framework of this configurator, the selection is limited to four height ranges. A more precise definition is made later during pre-dimensioning or verification with the LTB-x calculation programme. Bulk volume and/or necessary space for installations can also be decisive for the height.
_150-210 Small span
If fire protection is required, an additional layer is added below the web area (for elements with strip profiles _z26, _z53, _z80, for elements with board profiles Akustik klassik _k50g). Their height determines the fire resistance duration of the cross-section from 30 to 90 minutes. The fire resistance must be statically verified. If there are no requirements, the standard versions _z0 or _k50l are to be selected.
Panel designs with slat profiles and additional layer can be configured with an additional cavity (_p26, _p53) below the additional layer for installation guides, fixtures or to improve sound absorption. Cables laid there then do not penetrate the fire-protection layer. If required, the cavity is filled with insulating material (_p26mw, _p26ha) to improve acoustic absorption. If no cavity is necessary, the characteristic _p0 is selected.
_p0 No cavity
If the soffit of the element is to have a good sound-absorbing effect, the penultimate layer is configured as absorber _a50g. Otherwise, this layer is configured as a solid wood layer _a0.
_k50l Integrated absorber
The visible layer is profiled with joints. The code for profiling indicates in millimetres: Element width, strip width (rounded, from/to if applicable) and joint width (rounded) as well as a letter identification for variants, e.g. with chamfered strip edges or with additional height gradation.
Note: Some profiles indirectly cause exclusions for other configuration options.
_625-95-30 Slat profile
Various wood species are available for the visible layer. For quality reasons, individual wood species cannot be configured for all profiles; for technical reasons, surface treatments are excluded for some wood species.
_WTE Silver fir knotless, patterned
Depending on the type of wood, the optional application of a surface treatment is possible ex works. Individual colour finishes are always sampled for coordination. For elements in individual lengths, colour treatment is limited to max. 5 m length.
The face is subjected to a brushing _gb as standard, which produces a stronger or weaker structure depending on the type of wood and makes the surface less sensitive to scratches. Alternatively, a smooth sanding _gs can be carried out, or on request a bandsaw cut _grimitated.