Unseasoned Hardwood Shrinkage

Such as hardwood floor joists figures relating to the shrinkage from unseasoned to 12 moisture content are of greater importance.

Unseasoned hardwood shrinkage.

Allowance should therefore be made for shrinkage in unseasoned bearers joists and decking and for the gaps that will develop between the decking boards. Seasoning refers to the process of removing moisture from timber or drying timber. Shrinkage in unseasoned members. Hardwood species of high shrinkage eg.

For the hardwood species blackbutt spotted gum and ironbark an average shrinkage rate of approximately 6 8 should be assumed note. Shrinkage rates for some common australian species are provided in table 1. Wood shrinkage calculator width. Enter the actual measured width of the lumber in inches and fractions of an inch centimeters if metric.

Solid seasoned hardwood timber tends to have a superior dimensional stability to unseasoned hardwood timber and is much less prone to warping and splitting. The amount a piece of wood will shrink lengthwise called longitudinal shrinkage is so small typically about 0 1 to 0 2 that it is usually inconsequential to the volumetric shrinkage however plywood greatly benefits from the low longitudinal shrinkage of wood layers of wood veneer are glued together with the grain direction of each ply oriented perpendicular to the adjacent ply. Enter the initial moisture content mc. The figures in each class represent the average shrinkage that occurs from unseasoned to 12 moisture content.

An indication of shrinkage rates for individual species is given in technical data sheet 16 species properties and uses. Unseasoned timber can be expected to shrink as its moisture content reduces. Some other hardwood species can shrink in excess of 10. Seasoning hardwood timber enhances the basic properties of the timber increasing the stiffness bending strength and compression strength.

Consideration must be given in design construction to allow for shrinkage where unseasoned timber is used. This does not mean unseasoned timber is unsuitable for any use it just means you need to be aware of and maybe detail for any shrinkage that may occur. Shrinkage 6 mm per 100 mm should be expected for unseasoned hardwood. Once timber has dried to the moisture content of its environment called its emc it can and will of course continue to swell and shrink as it s environment changes.

Do not enter decimals or fractions and do not enter the percentage sign after the value. Partially seasoned timber can come from unseasoned timber that has partly dried or from seasoned timber used in a moist environment so that it has taken up moisture and increased in moisture content above 15 mc. Also included in the table.