Civil Engineering Reference
In-Depth Information
Scandinavia this method is becoming very popular, especially as a way of recy-
cling printed paper. Predecessors of this method, piles of old newspapers and
magazines in walls and floors, often fall out of old houses when they are demol-
ished. Newspaper has relatively good moisture-regulating properties and ther-
mal insulation properties. It works well as insulation as long as it is not exposed
to water or condensation as a result of settling or leakage into the wall. Untreated
newspaper, is however, a fire risk.
Some tree barks can also be of use as climatic material. Bark from cork-oaks is
very suitable for thermal insulation, as is the bark from birch, which has been one
of the most important waterproofing materials throughout history, especially as
an underlay for roofs covered with turf.
Tar extracted from coniferous and deciduous trees can be used for water-
proofing and impregnation.
All timber materials even moisture in the structure and indoor air. Wood
fibreboards have good wind-proofing properties. Cellulose fibre, when well
compressed into a wall, can have a wind-proofing effect, but a wind-proofing
system cannot be based on cellulose fibre alone, as the fibre may well settle after
a while.
Woodwool, wood shavings and shredded porous wood fibreboards can be used
as sealing around windows and doors. They are pushed in between the building
frame and door or window frame in the same way as linen strips, for example.
Timber resources are renewable. Many products are based on waste such as saw-
dust and cellulose, which in many parts of Europe is often burned or dumped.
Additives in some products have a bad environmental profile, e.g. boron salts in
cellulose fibre insulation and glues in some boards.
The primary energy used varies from product to product, but it is generally
much lower than similar products in other materials. Exceptions include wood
fibreboards which require high process temperatures and woodwool slabs which
use a lot of cement.
The problems of pollution through the different levels of production, usage
and waste are relatively small, except for a few additives in certain products.
Boron salts in cellulose fibre can pollute the soil and ground water if they are not
taken care of properly as waste.
Timber-based climatic materials can be generally considered extremely
durable and stable. Hardboard products should be re-usable. This is principally
the same for cellulose fibre and sawdust, which can be sucked out and then com-
pressed again in another situation.
With the exception of woodwool slabs and cellulose fibre with boron salts (fire
retardant), all products can become an energy source through burning. Pure tim-
ber products can be burned without specific smoke-cleaning systems, or they can
be made into compost.
