Preface

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

This edition has been revised with the following changes of significance:

a) 3-storey construction is now permitted, with revised design tables;

b) building widths have been increased from 8 m to 12 m;

c) revisions have been made to sealant and damp proofing requirements, and optional drainage layers have been added;

d) variable granular bed depths are now specified;

e) nail diameters and spacing have been included;

f) the minimum stud size has been increased from 38 mm x 89 mm to 38 mm x 140 mm; and

g) details for wall openings and walkouts have been revised.

The tabulated framing and plywood sheathing requirements have been recalculated based on the latest edition of CSA O86, Engineering design in wood.

Scope

1.1
This Standard applies to the selection of materials for, and the fabrication and installation of, preserved 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 preserved wood foundation, and for the use of preserved wood foundations enclosing crawl spaces (see Figures A.1 and A.6).

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 x mm) referring to standard dry dressed sizes and with imperial values (in x 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 (nonmandatory) to define their application.