Because glued-laminated timber is readily manufactured in large sizes, it is often used in Heavy Timber construction to meet minimum size and fire-resistance rating requirements of North American building codes.
For more information, please refer to the Fire Safety Design in Buildings book which provides basic information on the minimum sizes and arrangement of glulam members necessary to meet code requirements for Heavy Timber construction. Information is also provided on the means for calculating the fire resistance of glulam beams and columns.
- Select the section with the smallest cross-sectional area or the least weight required for the job.
- Use 38mm (1-1/2″) laminations and standard depths whenever possible.
- Use 38mm (1-1/2″) laminations in straight members and in all curved members with radius of curvature of 8400mm (27′) or more.
- Limit the size of glulam members to those which can be shipped economically and legally. This applies to both lengths and heights, since local overall shipping height limitations, usually about 4 to 6m (14′ to 20′), may restrict arch sizes.
- Use the proper appearance grade for the project by matching the appearance and thus the cost premium to the requirements for appearance and visibility.
- In some instances, using larger than necessary members may simplify overall economy by simplifying connection details. Consult manufacturer.
- Minimize the number of concealed or semi-concealed connections which require costly shop fabrication.
- Outline protection measures to be taken during erection to protect the members from damage, including provision for temporary bracing.
- Steel connections should be painted to prevent rust from staining the wood.
- They should be galvanized for high humidity service conditions.