Preface:

This is the fourth edition of CSA S406, Specification of permanent wood foundations for housing and small buildings. It supersedes the previous editions published in 2014, 1992, and 1983.

This edition has been revised with the following changes of significance:
a) Tables 5A to 5L and 10A to 10L series, as well as Tables 3A and 3B and 7A and 7B and some figures, have been modified to reflect the new load combinations in the National Building Code of Canada, 2015.
b) Reference to "preserved wood foundations" has been corrected to the new industry term of "permanent wood foundations".
c) More details have been added to the concrete footings supporting walls and columns.
d) Revised details have been added to the requirements for high wind and seismic forces.

The design provisions and tables have been updated to comply with the 2014 edition of CSA O86, Engineering design in wood, and the National Building Code of Canada, 2015.

Scope:

1.1
This Standard applies to the selection of materials for, and the fabrication and installation of, permanent wood foundations.

1.2
Specific details are provided for buildings up to three storeys in building height above the foundation and having a building area not exceeding 600 m².

1.3
This Standard provides for the optional use of wood sleeper, poured concrete slab, and suspended wood basement floor systems as components of the permanent wood foundation, and for the use of permanent wood foundations enclosing crawl spaces (see Figures A.1 and A.7).

1.4
The values given in SI (metric) units are the standard. The values given in parentheses are for information only.
Note: In commercial practice, nails are commonly identified by their length in inches. Lumber sizes are expressed in terms of thickness × width, with metric values (mm × mm) referring to standard dry dressed sizes and with imperial values (in × in) referring to nominal nondressed sizes, both in conformance to CSA O141.

1.5
In this Standard, "shall" is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard; "should" is used to express a recommendation or that which is advised but not required; and "may" is used to express an option or that which is permissible within the limits of the Standard. Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material. Notes to tables and figures are considered part of the table or figure and may be written as requirements. Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application.