Urban lumberjacking is a particular type of skipping

Skip (container)

A rubbish skip is usually called merely a skip or waste bin. A skip is a large open-topped container designed for loading onto a special type of lorry. Differing from dumpster, instead of being emptied into a waste vehicle onsite, a skip is replaced by an empty skip and then tipped at a landfill...

 (UK) or dumpster diving

Dumpster diving

Dumpster diving is the practice of sifting through commercial or residential trash to find items that have been discarded by their owners, but that may be useful to the dumpster diver.-Etymology and alternate names:...

 (US) where the focus is to salvage wood either for home construction

Home construction

Home construction is the process of constructing a home. Beginning with simple pre-historic shelters, home construction techniques have evolved to produce the vast multitude of living accommodations available today. Different levels of wealth and power have warranted various sizes, luxuries, and...

 projects or for home heating.

Deliberate encouragement by businesses

Waste disposal costs are increasing and so some businesses see the deliberate encouragement of this re-use as a means to reduce their own waste stream, and so to reduce their direct costs. The secondary benefits of being perceived as "green" may also be valued as a form of greenwashing. In the UK, Ikea

IKEA

IKEA is a privately held, international home products company that designs and sells ready-to-assemble furniture such as beds and desks, appliances and home accessories. The company is the world's largest furniture retailer...

 stores place a wood disposal crib near their car park and encourage shoppers to help themselves. This wood is a mixture of packaging, damaged furniture parts, and display shopfitting. As it is largely painted particle board

Particle board

Particle board, or particleboard , is an engineered wood product manufactured from wood particles, such as wood chips, sawmill shavings, or even saw dust, and a synthetic resin or other suitable binder, which is pressed and extruded...

, it's not appropriate for firewood or for external construction, but is still a popular source for indoor projects.

Carbon implications

Urban lumberjacking reduces the amount of carbon that would have been released into atmosphere compared to the amount that would have been released should it not have been performed.
This reduction is achieved in two different ways:

• Removing the wood from a skip reduces the amount of diesel burnt that would have been used transporting it to a landfill
  Landfill
  A landfill site , is a site for the disposal of waste materials by burial and is the oldest form of waste treatment...
  
  . This is only true however if the wood is taken from the site in a more efficient manner than a diesel truck. For instance multiple gas powered vehicles removing the same load actually produces more carbon.

• The proceeds of urban lumberjacking be used as wood fuel
  Wood fuel
  Wood fuel is wood used as fuel. The burning of wood is currently the largest use of energy derived from a solid fuel biomass. Wood fuel can be used for cooking and heating, and occasionally for fueling steam engines and steam turbines that generate electricity. Wood fuel may be available as...
  
   (which is carbon neutral) instead of fossil fuel
  Fossil fuel
  Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...
  
  s (e.g. coal
  Coal
  Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...
  
   or fuel oil
  Fuel oil
  Fuel oil is a fraction obtained from petroleum distillation, either as a distillate or a residue. Broadly speaking, fuel oil is any liquid petroleum product that is burned in a furnace or boiler for the generation of heat or used in an engine for the generation of power, except oils having a flash...
  
  ).