Case Studies of the Structural Aspects of 7 Recent

Purlins butted between rafters to provide lateral restraint. 

Consider equilibrium moisture content which depends on the control of the internal space conditions. Typical economicconditions for indoor pool controlled atmosphere is 70%RH and 28ºC for which EMC approx 13%. But for uncontrolled conditions, for example a translucent covered pool you could get average 90%RH and 15ºC which would give EMC of about 21%. For this you need to interpolate between dry (16%) and green stresses (25%). (Ref. TimberConstruction Manual, AITC). Consider heat effects. At 28ºC and 70%RH timber will lose about 7% of its strength. 

Sawn timber members

The same effects will occur. Creep is more of an issue because the timber is likely to be fixed at much higher moisture content than the EMC it will finally reach in service. Laminated members are fabricated at low moisture content and are also larger sections and creep is less of an issue.