INFORMATION BULLETIN
October 2006
97-IB-042
Page 1 of 5
ADJUSTABLE STEEL COLUMNS
IN RESIDENTIAL OCCUPANCIES
DISCUSSION
The use of adjustable steel columns (also known as “teleposts”) and engineered
columns has become a widespread practice in the homebuilding industry.
An adjustable steel column means any column that has been certified to meet the
prescriptive requirements of CAN/CGSB 7.2-M, "Adjustable Steel Columns" (maximum
working load greater than 8000 lbs., dimensions of materials meet specific
requirements, etc.).
An engineered column means, for the purposes of this STANDATA, an adjustable steel
column that does not meet the prescriptive requirements of CAN/CGSB 7.2-M,
"Adjustable Steel Columns."
Recently, confusion has arisen among suppliers, contractors and Safety Codes Officers
(SCO) concerning the acceptability of engineered columns as well as the footings that
support the columns.
This Information Bulletin describes how an SCO may accept the use of engineered
columns without requiring the direct involvement of a professional engineer for each
specific project (see also STANDATA 97-IB-020).
This Bulletin only addresses single family dwellings and multiple family dwellings that
contain 4 dwelling units or less and are 3 storeys or less in height. These residential
occupancies fall within the scope of the exemption from professional involvement as
described in Clause 2.3.3.1.(2).(b). of the Alberta Building Code 1997.
This Bulletin also details the requirements for the design of the footings associated with
adjustable steel columns and engineered columns.
ISSUE OF THIS INFORMATION BULLETIN IS
AUTHORIZED BY THE DIRECTOR/
ADMINISTRATOR.
[Original Signed]
C.M. TYE
Alberta Municipal Affairs, 16th Floor, Commerce Place, 10155 – 102 Street, Edmonton, Alberta, Canada, T5J 4L4
Safety Codes Council, Suite 800, 10707 – 100 Avenue, Edmonton, Alberta, Canada, T5J 3M1
This Bulletin is not applicable to other types of columns that may be used in one- and
two-family dwellings (i.e. engineered wood, cold-formed structural steel, laminated
lumber, etc.).
COLUMNS
Adjustable steel columns are required by Sentence 9.17.3.4.(1). of the Alberta Building
Code 1997 (ABC) to conform to CAN/CGSB 7.2-M, "Adjustable Steel Columns."
Columns manufactured to that standard have a maximum allowable working load
greater than 36 kN (8000 lbs), and have a minimum and maximum outside diameter of
63 mm (2.50 in.) and 86 mm (3.38 in.), respectively. This is to allow for the installation of
the columns in 51x100 mm (2x4) frame-constructed walls.
Engineered columns and their associated connections and fittings must be designed
according to the provisions of Part 4 of the ABC, which requires professional
involvement for the design and conformance to CAN/CSA-S16.1, "Limit States Design
of Steel Structures."
Traditionally, this would mean professional involvement on a case-by-case basis for
each project that includes engineered columns. However, it would be acceptable for
manufacturer’s to submit pre-engineered packages of column drawings to the authority
having jurisdiction (AHJ) to be retained on file. These packages must be imprinted with
the stamp of a professional engineer registered to practice in the province of Alberta.
At the time of application for a building permit, the applicant must submit evidence to the
AHJ detailing which engineered column will be used (manufacturer, model #, etc.). If the
AHJ does not already have the pre-engineered package, the applicant must submit a
set of column drawings imprinted with the stamp of a professional engineer registered to
practice in the province of Alberta.
Additionally, it would be acceptable for contractors to use engineered columns that have
been evaluated by the Canadian Construction Materials Centre (CCMC) and are
deemed to be acceptable alternatives to the prescriptive requirements in the Code.
CCMC evaluations will include the design of the engineered column, including all
associated fittings and connections. It is possible that the CCMC evaluation could
include the design of the footing as well. Engineered columns that have been evaluated
by CCMC and include the design of the footings must be installed exactly according to
the terms of the evaluation regarding loads, installation conditions and soil conditions for
the footing.
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FOOTINGS
Footings supporting adjustable steel columns or engineered columns can be designed
in one of two ways.
1. Unreinforced concrete meeting the requirements of Subsection 9.15.3.
2. Reinforced concrete designed according to Part 4 in compliance with CSA A23.3,
"Design of Concrete Structures."
Unreinforced Concrete
If the column footings are designed using unreinforced concrete, the minimum
allowable thickness is 100 mm (4 in.) according to Sentence 9.15.3.6.(1). This
thickness may have to be increased to be not less than the projection of the
footing beyond the column base plate.
Note that there are conditions on the use of unreinforced concrete, as detailed in
Article 9.15.3.3. (See CODE REFERENCES at the end of this document.)
See also STANDATA 97-DI-010 for more information.
Reinforced Concrete
If the design of the footings include the use of reinforced concrete or if the design
cannot meet the requirements for unreinforced concrete detailed in Article
9.15.3.3., then the design of the footings must conform to Section 4.2.
Concrete under Part 4 must be designed by a professional engineer and must
conform to the design requirements of CSA A23.3, "Design of Concrete
Structures."
According to the requirements of CSA A23.1 and A23.3, the minimum thickness
of footings for reinforced concrete would be 225 mm, accounting for concrete
cover above and below the reinforcement. This minimum thickness may have to
be increased due to local soil conditions, applied loads or size of reinforcing.
An applicant for a building permit that includes reinforced concrete footings
supporting adjustable steel columns or engineered columns must submit
evidence to the AHJ that the design of the footings has been performed by a
professional engineer registered to practice in the province of Alberta. Evidence
must also be supplied to show that the footing design is appropriate for local soil
conditions.
Pre-engineered footing designs would be considered to be acceptable, provided
the designs can be shown to be appropriate for local soil conditions.
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CODE REFERENCES
2.3.3.1. General
…
2) Except as required in Sentence (8), architect and engineer seals and stamps
are not required on plans or specifications for the following buildings:
…
b) a building classified as residential occupancy that,
i) is a single family dwelling, or
ii) is a multiple family dwelling, that contains 4 dwelling units or less and is
3 storeys or less in height;
4.2.3.5. Concrete
1) Plain, reinforced or prestressed concrete used in foundations or in support of
soil or rock shall conform with the requirements of Subsection 4.3.3.
4.3.3.1. Design Basis for Plain, Reinforced and Prestressed Concrete
1) Buildings and their structural members made of plain, reinforced and
prestressed concrete shall conform to CSA A23.3, "Design of Concrete
Structures." (See Appendix A.)
9.15.3. Footings
9.15.3.1. Footings Required
1) Footings shall be provided under walls, pilasters, columns, piers, fireplaces
and chimneys that bear on soil or rock, except that footings may be omitted
under piers or monolithic concrete walls if the safe loadbearing capacity of the
soil or rock is not exceeded.
9.15.3.2. Support of Footings
1) Footings shall rest on undisturbed soil, rock or compacted granular fill.
9.15.3.3. Footing Sizes
1) Except as provided in Sentences (2) to (8) and in Articles 9.15.3.4. and
9.15.3.5., the minimum footing size shall be as shown in Table 9.15.3.3.
provided the span of supported joists does not exceed 4.9 m and the
specified live load on any floor supported by the footing does not exceed 2.4
kPa. (See Table 4.1.6.3.)
2) Where the specified live load exceeds 2.4 kPa, footings shall be designed in
accordance with Section 4.2.
Table 9.15.3.3. Minimum Footing Sizes
3) Except as provided in Sentence (4), where the span of the supported joists
exceeds 4.9 m, footings shall be designed in accordance with Section 4.2.
4) Where the supported joist span exceeds 4.9 m, footing sizes are permitted to
be determined according to the calculation provided in Appendix A.
5) The strip footing sizes for exterior walls shown in Table 9.15.3.3. shall be
increased by 65 mm for each storey of masonry veneer over wood frame
construction supported by the foundation wall.
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6) The strip footing sizes for exterior walls shown in Table 9.15.3.3. shall be
increased by 130 mm for each storey of masonry construction supported by
the foundation wall.
7) The minimum strip footing sizes for interior walls shown in Table 9.15.3.3.
shall be increased by 100 mm for each storey of masonry construction
supported by the footing.
8) The footing area for column spacings other than shown in Table 9.15.3.3.
shall be adjusted in proportion to the distance between columns.
9.15.3.6. Thickness
1) Footings shall be not less than 100 mm thick except when greater
thicknesses are required because of the projection of the footing beyond the
supported element.
9.15.3.7. Footing Projection
1) The projection of an unreinforced footing beyond the supported element shall
be not greater than the thickness of the footing.
9.17.3.4. Adjustable Steel Columns
1) Adjustable steel columns shall conform to CAN/CGSB 7.2-M, "Adjustable
Steel Columns."
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