Amount of Shrinkage

Amount of shrinkage: - Study Article 162. Wood in an air-dry condition has reached about one-
ha1f of its possible shrinkage. Length wise shrinkable is ngligi1e because the thickness of the
end walls of the wood elements is very snail hen compared to the length of these elements.
Shrinkage in a direction tangential to the annual rings is about twice as great as in a radial
direction. Considerable force is evoked when confined wood sells due to the absorption of water.

This is strikingly shown in an illustration in Engineering news, 70,615, September 25, 1913. Slab
of oak veneered with maple were taxied in a basement to within 1 inch of the lower side of a 12
by 24 inch reinforced concrete bean which formed Part of the first floor framing. The wood was
saturated during a flood which caused it to swell. The force developed, raised the beam 3 inches
at the point of contact making its replacement necessary. The shrinkage from green to over-dry
condition for different species of wood is given in Table 1, which faces page 196.

Principal native woods: - Study Articles 167, 168, 173, 174, 185,