Moss And Grass Materials

Basic info is found in Chapter 10.

Many moss and grass species have considerable potential as climatic materials. Loose fill, boards, blocks and matting of different grasses give quite good thermal insulation, often comparable to the more industrialized insulation products. Most plant fibres also have good moisture buffering properties, and some even have a high resistance to rot, such as flax, hemp, eelgrass and moss. Plant materials are naturally combustible and where there are fire requirements must either be treated with a fire retardant or clad with incombustible materials.

Plant products often make suitable thermal insulation because, in a dry state, they contain a high amount of air and have an elastic structure that limits settling. Straw, eelgrass, lichen and moss can be dried and used as loose fill. With grasses such as flax, hemp and nettles the fibres are used to make mats or boards after removal of fruits and leaves. Additional glues are then most often added. Grasses can also be used as a source of cellulose based insulation (see page 289).Table 14.9

For air regulating purposes these materials are often used as felt strips or compressed loose fill for sealing of gaps between windows, doors and the building fabric. This is a critical part of the structure and needs high durability. Materials used in this way are flax, hemp, moss and fibres from nettles.

Ecologically speaking, grass materials are very attractive. They are either renewable resources that are wild or by-products of agriculture and food production. However, some of the glues, flame retardants and fungicides used have a doubtful environmental profile. In many cases, they will be as for the wood-based products (see page 280).

The energy used in the production processes varies considerably from product to product, but it is generally lower than that of similar products in other materials. Exceptions include insulation products glued with large amounts of synthetic compounds.

Pollution arising from the different levels of production, usage and waste is relatively small. The ability to store carbon should also be accounted for. During construction plant products often cause some dust and the wearing of simple masks would be advisable. Dust from hemp and cotton is problematic. In an indoor climate, plant materials

Table 14.9 Acclimatizing qualities of moss and grass materials

Material

Composition

Areas of use

Turf1

Earth with living grasses

Thermal insulation, sound insulation

Straw, loose fill2 and bales

Stalks, possibly mixed with clay

Thermal insulation, sound insulation, moisture buffering

Straw softboards

Stalks, glued by natural ingredient, often covered with a layer of cardboard

Thermal insulation, sound insulation, moisture buffering

Grass fibres, matting and felts

Defibrated plant fibres, glued with polyolefins or polyesters (melting fibres), additives3

Thermal insulation, sound insulation, moisture buffering

Linseed oil putty

Linseed oil, stone flour

Sealing of joints

Moss

Whole plant

Sealing of joints, thermal insulation, moisture buffering

Peat, loose fill

Crumbled and dried peat, lime

Thermal insulation, sound insulation, moisture buffering

Peat, matting and soft boards

Compressed peat, matting are sewed inn between sheets of paper

Thermal insulation, sound insulation, moisture buffering

Cellulose fibre, loose fill

Recycled cellulose fibre, borax, boric acid

Thermal insulation, moisture buffering, sound insulation

Cellulose fibre, matting

Recycled or virgin cellulose fibre, glued with polyolefines or polyester (melted), additives3

Thermal insulation, moisture buffering, sound insulation

Cellulose building papers and sheets

Recycled or virgin cellulose, sheets are laminated with polyvinyl acetate etc. possible additives of latex, bitumen etc.

Vapour retarders, air barriers, wind barriers

1 Discussed in Chapter 15, Surface materials.

2 Thatching is dicussed in Chapter 15, Surface materials.

3 Se page 280.

1 Discussed in Chapter 15, Surface materials.

2 Thatching is dicussed in Chapter 15, Surface materials.

3 Se page 280.

often have good moisture regulating properties and represent no known hazards with regard to emissions. However, additives may change this picture. Pure products can be either burned for energy recovery or composted after use; when composted, special care should be taken to avoid eutrophication of groundwater. For products containing adhesives, special waste treatment and incineration is required.

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