Wood fiber insulation board

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Wood fiber insulation board
STEICO flex Natural Wood Fiber Insulation.jpg
origin
raw materials Wood, e.g. T. rubber , paraffin , bitumen
Primary energy consumption (production) 600-785 kWh / m³
Material properties
Thermal conductivity  λ fixed: 0.040 W / (m · K )
flexible: 0.040–0.060 W / (m · K)
Specific heat capacity  c 2100 J / (kg K)
Bulk density ρ fixed: 110–250 kg / m³
flexible: 40–60 kg / m³
Vapor diffusion resistance  μ fixed: 5–10, flexible: 1–2
commitment
material costs 40–50 € / m² at 0.2 W / (m² · K)

Wood fiber insulation boards , sometimes wood fiber panels or soft wood fiber boards called, a kind of are fiber plates , namely, made of wood fiber panels insulation materials , mostly for thermal insulation are used Außenhüllflächen of a building. Some of them are also used in drywall construction for the construction of internal building parts (walls, floors). They are among the oldest industrially produced natural insulation materials and were already produced in the first half of the 20th century.

They are not to be confused with the wood wool lightweight panels .

production method

Wood fiber insulation boards are generally at least 85% of wood fibers from Sägeresten in wet or dry process ( rind , splinters ) and wood chips are obtained. Softwoods are preferred as the starting material because of their higher fiber quality. In the wet process, the fiber content can be up to 100%, as there is no need for any binding agent.

Wet process

In the wet process, the raw materials are first ground and then mixed with up to 98% water to form a paste. This slurry, after the intermediate storage in deckle formed on the molding machine for so-called fiber cake. After the water has been largely pressed out mechanically, the fiber cakes are cut to size and dried in a drying tunnel at temperatures between 160 and 220 ° C. The addition of binders is usually not necessary, as the lignin portion of the wood, which is liquid when heated, binds the particles together when it cools. For special purposes (increased strength, water-repellent properties ), substances containing resin or bitumen may be added to the paste . The panels are then cut, stacked and packaged; for thicker panels, they are glued in layers. If the production conditions are good, all dust or panel remnants flow back into the production cycle.

Dry process

In the dry process, the fibers are dried immediately after digestion and then mixed with around 4% PUR resin . In order to produce flexible insulation boards, synthetic textile fibers or fibers made from corn starch are added to the wood fibers. Then they are sprinkled on in the desired thickness, pressed, hardened by a mixture of steam and air and the panels are then cut, stacked and packaged.

Technical characteristics

Wood fiber insulation boards (HDP) have a WLG value of up to 040 and are therefore comparable in terms of insulation performance to cellulose , hemp fiber , sheep wool , rock wool . Polystyrene is available in WLG 040, 035 and occasionally (as of 2010) also 032. Mineral insulating materials are clearly superior to HDP in terms of specific heat capacity ; At 2100 J / (kg · K), this is significantly higher than that of mineral insulation materials and thus enables good thermal insulation in summer .

Wood fiber insulation boards are classified in building material class B2 or E, i.e. they are normally inflammable. Wood fiber insulating materials can absorb a lot of moisture and only lose their insulating properties when the water content exceeds 20 percent by weight.

In terms of sound insulation, they achieve sound insulation levels of up to R w, P  = 56 dB for external walls, up to R w, P  = 62 dB for light partition walls, and even up to R w, P  = 79 dB for wooden beam ceilings . With impact sound insulation, standard levels of up to L n, w, P  = 34 dB are achieved.

Areas of application

Subsequent thermal insulation of a house roof with wood fiber insulation panels in combination with cellulose blow-in insulation

Wood fiber insulation boards are suitable for all applications in which no permanent increased moisture penetration is to be expected. They have a particularly high market share in roof insulation and interior insulation , as they offer economic and structural advantages here.

They are also used for external wall , ceiling and floor insulation as well as in cavities (between rafters , partition walls , layers of beams ). Special, soft wood fiber insulation boards are also suitable for airborne sound and footfall sound insulation even with increased requirements (apartment separating ceilings).

processing

When used outdoors, it can lead to moisture from driving rain or high humidity. The same applies to improper storage of the panels. We recommend plastering the panels only if the moisture content is below 13% in order to avoid cracking due to shrinkage and discoloration due to the penetration of wood constituents. If no measuring device is available, an area of ​​around 70 × 70 cm can be masked with a film to determine whether condensation has formed on the inside of the film within 24 hours. In this case the panels are too damp. In addition, manufacturers of thin plaster systems recommend the application of a primer as a primer with the purpose of a burn-on barrier , adhesive bridge or a barrier primer .

The panels are typically glued with a fine clay plaster (e.g. clay finishing plaster or clay adhesive). The use of a pure lime plaster is usually not recommended because of the risk of scorching , unless the surface is not very absorbent or a newly built wall whose masonry moisture is still very high. Instead of a clay mortar, a commercially available adhesive and reinforcement mortar can be used, which, however, can significantly reduce the water vapor permeability and capillarity depending on the synthetic resin content and layer thickness .

Another prior to the application layers on the insulation boards is a coating of adhesive or in different cases RFP and fabrics recommended:

  • Outside areas where moisture and heat expansion due to driving rain and solar radiation is to be expected. Adhesive clay mortars are not suitable for regular exposure to moisture.
  • If, as with the usual thermal insulation composite systems, only a thin layer of high-grade plaster is applied instead of the base and finishing plaster , the reinforcement layer increases the crack resistance and the strength of the system against impact loads.
  • When installing wall heating or when using less elastic, highly hydraulic plasters that tend to form a layer (e.g. plaster with more than just a small amount of cement), the application of an adhesive mortar improves the bond with the insulation board.
  • In the case of interior insulation in rooms with high levels of moisture, such as bathrooms and kitchens, the application of a mortar with an increased synthetic resin content can prevent the accumulation of moisture in the insulation boards. Adhesive mortars, reinforcement adhesives, thin-layer and finishing plasters as well as other dry mortars that are intended for application in layers of less than 7 mm (and are not clearly declared as "pure lime" products) usually have a vapor diffusion resistance μ of at least 25. This does not apply to clay adhesive mortars.

The fabric should not lie directly on the insulation material. Usually it is provided that it is located in the upper half or in the upper third of the adhesive layer. A two-layer application is recommended to smooth an uneven insulation layer, to increase strength or if staining substances in the wood are feared to penetrate through, e.g. by first applying a 3 mm thick layer (" basic filler ") and then applying another 5 mm after it has hardened The layer thickness follows, in which the reinforcement fabric is coated. In some cases, a thin layer of wet-on-wet with a layer thickness of about 1 mm is recommended after the fabric has been applied. The mesh size of the fabric is usually 4 × 4 to 8 × 8 mm. A standing time of at least one day is recommended for every millimeter of application thickness before the next layer is applied. In the case of clay plaster, the drying process must be roughened up after each intermediate layer, for example by spreading it with a hard brush, street broom, steel brush or notched trowel.

To limit the moisture ingress into the insulation boards from the room air, the manufacturer Gutex generally recommends an sd value of the surface coatings of 0.2 to 0.5 m in total. The higher value should be selected in rooms with increased humidity.

Market importance

Wood fiber insulation boards have been produced since the 1930s and are therefore among the oldest industrially produced natural insulation materials. One of the first major manufacturers in Germany was the Groß Särchen cardboard paper factory . Wood fiber insulation boards currently have a share of just over 1% in the overall insulation market. In the market segment of insulation materials made from renewable raw materials , they have a market share of 28% and are therefore the dominant natural insulation material alongside cellulose with a market share of 32% .

Norms

  • EN 13171 Thermal insulation products for buildings - Factory made wood fiber (WF) products - Specification .

literature

  • Holzbau manual wood fiber insulation materials . In: Informationsdienst Holz , Series 4, Part 5, Volume 2, 2007, Informationsverein Holz eV (PDF)

Web links

Individual evidence

  1. ↑ Insulation materials made from renewable raw materials . Agency for Renewable Resources, 2008, p. 9
  2. ↑ Constructions with building materials made from renewable raw materials . Competence Center for Building with Renewable Resources, 2006, p. 20.
  3. ↑ Ingo Gabriel, Heinz Ladener (ed.): From old buildings to low-energy and passive houses . Ökobuch-Verlag, 2008. pp. 74-75, ISBN 9783936896329
  4. ↑ a b c wood construction manual wood fiber insulation materials . In: Informationsdienst Holz , Series 4, Part 5, Volume 2, 2007, pp. 4–5, Informationsverein Holz eV (PDF)
  5. ↑ a b J. Spritzendorfer: Sustainable Building with "healthy living" building materials . Heidelberg, 2007, ISBN 978-3-7880-7802-7 , p. 58
  6. ↑ Insulation materials made from renewable raw materials . Agency for Renewable Resources, p. 9
  7. ↑ Steico: Summer thermal protection . P. 4 (manufacturer information)
  8. ↑ W. Eicke-Hennig: Insulation materials made from waste paper or natural fibers - (not) an alternative? In: Bauthema Naturdämmstoffe, 2006, ISBN 3-8167-6916-0
  9. ↑ Holzbau manual wood fiber insulation materials . In: Informationsdienst Holz , Series 4, Part 5, Volume 2, 2007, p. 10, ISSN  0466-2114
  10. ↑ a b wood construction manual wood fiber insulation materials . In: Informationsdienst Holz , Series 4, Part 5, Volume 2, 2007, pp. 8–9, ISSN  0466-2114
  11. ↑ Processing instructions: STEICOprotect ETICS, plaster-coatable wood fiber insulation board STEICOprotect dry , p. 9., In: Steico.com; accessed in May 2019
  12. ↑ The manufacturers recommend the following reinforcement mortars: Baumit multiContact MC 55 W, 6-8 mm. Dracholin universal plaster UP 2000, 5–8; Dracholin universal plaster UP light, 5–8 mm; Dracholin UP 700 construction adhesive (for the plinth area), 5–8 mm. Gräfix 71 lite, grain size 0–2 mm, layer thickness 8–10 mm; gräfix 76 adhesive and coating mortar, min. 5 mm. Knauf Lustro, 5–15 mm; Pommel Luis, 4-5 mm; Knauf SM700, 5-7 mm; Knauf SM700, Pro 5-10 mm. Maxit multi 292, light adhesive u. Reinforcement mortar, MG P II, CS III, 5-7 mm; maxit multi adhesive and reinforcement mortar E, 5-7 mm. Quickmix leveling and adhesive mortar light SKS-L. Sakret adhesive and reinforcement mortar white KAMw, mortar group GP CS IV W2, in 5-8 mm. SCHWENK SK light reinforcement mortar / filler adhesive. Unger Diffutherm Udi base filler, 5 mm. VWS adhesive and reinforcement mortar light HS white. Weber.therm 300, 5-8 mm; weber.therm 301, 4-7 mm; weber.therm 302, 5-8 mm; weber.therm 304, 5–8 mm.
    And only for indoor and protected outdoor areas: Claytec clay adhesive and reinforcement mortar 13.555, from 3 mm; Claytec clay finishing plaster fine, from 3 mm. maxit purcalc 315, thin-layer lime plaster.
    Some of the recommended layer thicknesses are given. In the case of a two-layer application, the first layer of filler can usually be from approx. 3 mm thick.
    Source u. a. Claytec worksheet interior insulation - inner shell made of insulation boards - inner shell made of light clay - inner shell made of light earth bricks , as of January 2019; Pavatex exterior plastering systems , as of April 2018.
  13. ↑ Michael Carus et al .: Study on the market and competitive situation for natural fibers and natural fiber materials (Germany and EU). Gülzower Expert Discussions, Volume 26, Fachagentur Nachwachsende Rohstoffe e. V., 2008, p. 180, nova-institut.de (PDF; 4 MB)