Sawdust and wood shavings

Loose fill of sawdust and wood shavings is timber in a very pure form, and can be used as thermal insulation in walls, floors and ceilings (Table 14.8). Sawdust and wood shavings are fine-particled, hygroscopic materials that take up moisture and release it into the air in

Table 14.8 Thermal properties of sawdust and wood shavings

Material

Weight (kg/m3)

Specific thermal conductivity [W/m K]

Sawdust

Compressed

120

0.071

Well compressed

200

0.081

Mixed with sand (2:1)

750

0.100

Wood shavings

Slightly compressed

80

0.120

Compressed

130

0.080

Well compressed

150

0.070

Highly compressed

180

0.060

Rinsed and slightly compressed

80

0.045

Rinsed and compressed

125

0.055

(Source: Granum, 1951; Baufritz, 2007)

(Source: Granum, 1951; Baufritz, 2007)

14.16

Wood shavings as thermal insulation in industrialized building. Carrying out the insulation work at the factory secures complete filling of the building elements. Source: Baufritz.

14.16

Wood shavings as thermal insulation in industrialized building. Carrying out the insulation work at the factory secures complete filling of the building elements. Source: Baufritz.

the same way as timber, but at a slightly higher rate. They also have the same resistance to fungus and insects as timber.

Commercial products based on wood shavings have had a certain success in the central European market. There are two main versions, differing in the type of fire and insect protection used. Most common is a product where whey and soda are added for these two purposes, respectively; the other adds up to 25% liquid cement for both purposes.

Production of these materials requires little energy - except where cement is added - and they are benign in the finished building. Experimental buildings investigated by Professor Bugge at the Norwegian Institute of Technology demonstrated that after 30 years the sawdust was in perfect condition, with no sign of deterioration. The buildings stood on the very damp west coast of Norway (Granum, 1951). Loose fill can fairly easily be taken out and re-used.

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