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unsupported basement height OBC part 9: 9.15.4.2

sunyaer

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Joined
Apr 21, 2022
Messages
338
Location
Toronto
For Ontario building code part 9:

In tables 9.15.4.5.A. to 9.15.4.5.C. , there is "maximum Unsupported Basement Wall Height". In the meanwhile, there is this sentence: "9.15.4.2.(3) Foundation walls made of flat insulating concrete form units shall be laterally supported at the top and at the bottom". Further, as for lateral support at the bottom, 9.15.4.4. lists conditions accepted for flat insulating concrete form foundation walls being laterally supported at the bottom:
9.15.4.4. Foundation Walls Considered to be Laterally Supported at the Bottom
(1) Flat insulating concrete form foundation walls shall be considered to be laterally supported at the bottom where the foundation wall,
(a) supports backfill not more than 1.2 m in height,
(b) is supported at the footing by a shear key and is supported at the top by the ground floor framing, or
(c) is dowelled to the footing with not less than 15M bars spaced not more than 1.2 m o.c.

Questions:

1). Is the requirement of 9.15.4.2.(3) for the construction stage or for the completed condition of the foundation walls?

2). What is the use of tables 9.15.4.5.A. to 9.15.4.5.C.? For determining the backfill height before installation / completion of the lateral supports at the top and at the bottom required by 9.15.4.2.(3)?

3). What is the use of clause 9.15.4.4.? To be used for conditions to meet the requirement of 9.15.4.2.(3) for support at the bottom?

4). To satisfy 9.15.4.4. (c), minimum 15M bars shall be used, but there is no 15M bars in tables 9.15.4.5.A. to 9.15.4.5.C., therefore, assume a foundation wall is designed by using tables 9.15.4.5.A. to 9.15.4.5.C, the foundation wall would not satisfy 9.15.4.4. (c), then if backfill is more than 1.2 m in height (usually it is), only 9.15.4.4. (b) would be a condition to provide the support at the bottom of the completed condition of the foundation walls. Am I looking at these clauses in a wrong way?
 
1. It would be construction completion. The code regulates the building after construction is complete, It provides no guidance on temporary bracing of shoring during construction.

2. Correct.

3. Correct.

4. Reinforcement detailed in the tables is the minimum requirement. Other clauses can dictate more restrictive requirements based on specific circumstances.

For instance, a constructor may choose to install 15M bar to meet 9.15.4.4., rather than have the wall considered unsupported at the bottom.
 
...

4. Reinforcement detailed in the tables is the minimum requirement. Other clauses can dictate more restrictive requirements based on specific circumstances.

For instance, a constructor may choose to install 15M bar to meet 9.15.4.4., rather than have the wall considered unsupported at the bottom.
Just happened to find some information from the web.
--------------------------------------------------------------------------------------------------------------
Once the 2020 code goes into effect, builders will no longer be limited to using only 15M
rebar dowels for lateral support at the bottom of ICF foundation walls. Thanks to the change,
there will also be an option to use 10M rebar with narrower spacing; this is welcome news,
since 10M bar is more typical in the field and is easier to handle. Here are the new code’s
rebar and spacing requirements for lateral reinforcement of foundation ICF walls:

15M rebar dowels spaced no more than 1.2 m on center
10M rebar dowels spaced no more than 600 mm on center
-------------------------------------------------------------------------------------------------------------
 
MAGA Code has both metric and imperial measurements....so much easier to understand.
 
Just happened to find some information from the web.
--------------------------------------------------------------------------------------------------------------
Once the 2020 code goes into effect, builders will no longer be limited to using only 15M
rebar dowels for lateral support at the bottom of ICF foundation walls. Thanks to the change,
there will also be an option to use 10M rebar with narrower spacing; this is welcome news,
since 10M bar is more typical in the field and is easier to handle. Here are the new code’s
rebar and spacing requirements for lateral reinforcement of foundation ICF walls:

15M rebar dowels spaced no more than 1.2 m on center
10M rebar dowels spaced no more than 600 mm on center
-------------------------------------------------------------------------------------------------------------
That may just refer to the national version of the code. That page of my Ontario Building Code is mysteriously missing...
 
Just happened to find some information from the web.
--------------------------------------------------------------------------------------------------------------
Once the 2020 code goes into effect, builders will no longer be limited to using only 15M
rebar dowels for lateral support at the bottom of ICF foundation walls. -------------------------------

Note that in some situations, designers may want to use the ICFMA manual, which is essentially an engineered design guide for ICF in certain situations (inc. high winds, seismic areas, openings near corners), and that in those cases, the design manual may lay down more stringent dowelling tie-in requirements.
 
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