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BCC Ruling No. 15-35-1424

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Ruling No.: 15-35-1424
Application No.: B 2015-33

 

BUILDING CODE COMMISSION

IN THE MATTER OF Subsection 24(1) of the Building Code Act, S.O. 1992, c. 23, as amended.

AND IN THE MATTER OFSentence 9.12.2.1.(1), Clauses 9.12.2.2. (7)(c) and (e), and Clause 4.2.4.1. (1)(c) of Regulation 332/12 as amended, (the “Building Code”).

AND IN THE MATTER OF an application by Dwayne Strom, for the resolution of a dispute with Travis Rob, Chief Building Official, to determine whether the use of deck blocks as the footings for the as-constructed deck, provides sufficiency of compliance with the technical requirements of Sentence 9.12.2.1.(1), Clauses 9.12.2.2. (7)(c) and (e), and Clause 4.2.4.1. (1)(c) of Division B of the Building Code at 1301 Emo Road, Town of Fort Frances, Ontario.

APPLICANT

Dwayne Strom
Home Owner
Fort Frances, Ontario

RESPONDENT

Travis Rob
Chief Building Official
Fort Frances, Ontario

PANEL

Tony Chow, Chair
Yaman Uzumeri
Gary Burtch

PLACE

City of Toronto, Ontario

DATE OF HEARING

November 5, 2015

DATE OF RULING

November 5, 2015

APPEARANCES

Dwayne Strom
Home Owner
Fort Frances, Ontario
Applicant

Travis Rob
Chief Building Official
Fort Frances, Ontario
Respondent

RULING

 

1. Particulars of Dispute

The applicant received an Order to Comply under the Building Code Act, 1992, to remedy certain alleged deficiencies at 1301 Emo Road, Town of Fort Frances, Ontario.

The subject building is a 1 storey, Group C occupancy building. The dispute relates to the construction of a new larger sized deck, which replaces an existing wood deck. The new deck, which is located at the rear of the existing dwelling, has been constructed and is approximately 35 m² in area, 1.22 m (4 feet) high from the finished ground to the underside of the floor joists. The deck is not supporting any roof structure, and is attached to the home by way of a ledger board bolted to the rim joist of the house. Deck blocks at grade level act as the footings to support the new deck.

Sentence 9.12.2.2.(1) of the Building Code, states that the minimum depth of foundations below finished ground level must conform to Table 9.12.2.2., which requires foundations to have a minimum of 1200 mm below existing grade for clay soils.

Sentence 9.12.2.2.(7) provides an exception to Sentence (1) as it states, “The foundation depths required in Sentence (1) do not apply to foundations for decks and other accessible exterior platforms, (a) that are of not more than 1 storey, (b) that are not more than 55 m² in area, (c) where the distance from the finished ground to the underside of the floor joists is not more than 600 mm, (d) that are not supporting a roof, and (e) that are not attached to another structure, unless it can be demonstrated that differential movement will not adversely affect the performance of that structure”.

Clause 4.2.4.1.(1)(c) states, “The design of foundations, excavations and soil- and rock-retaining structures shall be based on a subsurface investigation carried out by a person competent in this field of work, and on any of the following: (c) in situ testing of foundation units such as the load testing of piles, anchors or footings carried out by a person competent in this field of work.”

The dispute for the Commission to determine is to whether the use of deck blocks as footings for the as-constructed deck, provides sufficiency of compliance with Sentence 9.12.2.2.(1) when considering Clause 4.2.4.1.(1)(c) and the exceptions provided in Sentence 9.12.2.2.(7).

2. Provisions of the Building Code in Dispute

9.12.2.1. Excavation to Undisturbed Soil
  1. (1) Excavations for foundations shall extend to undisturbed soil.
9.12.2.2. Minimum Depth of Foundations
  1. (7) The foundation depths required in Sentence (1) do not apply to foundations for decks and other accessible exterior platforms,
    1. (a) that are of not more than 1 storey,
    2. (b) that are not more than 55 m² in area,
    3. (c) where the distance from the finished ground to the underside of the floor joists is not more than 600 mm,
    4. (d) that are not supporting a roof, and
    5. (e) that are not attached to another structure, unless it can be demonstrated that differential movement will not adversely affect the performance of that structure.
4.2.4.1. Design Basis
  1. (1) The design of foundations, excavations and soil- and rock-retaining structures shall be based on a subsurface investigation carried out by a person competent in this field of work, and on any of the following:
    1. (a) application of generally accepted geotechnical and civil engineering principles by a person especially qualified in this field of work as provided in this Section and other Sections of this Part,
    2. (b) established local practice where such practice includes successful experience both with soils and rocks of similar type and condition and with a foundation or excavation of similar type, construction method, size and depth, or
    3. (c) in situ testing of foundation units such as the load testing of piles, anchors or footings carried out by a person competent in this field of work.

3. Applicant’s Position

The Applicant submitted that he received a building permit to construct a new deck at the rear of his home which would replace his old deck. He advised that the new deck, although somewhat larger, had been constructed in the same manner as his old deck. He stated that both decks were constructed using deck blocks as footings for the deck. In describing the construction of the deck, the Applicant advised that the deck was approximately 35 m² in building area, 1.22 m (4 feet) high, attached to the home, and supported by deck blocks.

The Applicant informed the Commission that numerous decks Fort Frances have been constructed using deck blocks as footings. To support his position, the Applicant submitted multiple photos of various decks reported to be constructed in the area with deck blocks as footings.

The Applicant reported that the previous Chief Building Official, since retired, had approved the construction of several decks with deck blocks as footings in the area. The Applicant advised that it was a common past practice to use deck blocks as footings, and as such numerous decks in the area have been constructed in this manner over the years and were considered to be in compliance with the Building Code at the time of their construction. The Applicant reported that the decks so constructed are not known to have caused any damage to the dwellings or structures to which they have been attached. The Applicant advised that to his knowledge there has only been one deck failure in town, and that happened to be a deck built using sono tubes, which lifted due to frost.

In support of the Applicant’s statement and in response to questions, the retired Chief Building Official of Fort Frances and witness for the Applicant reported that he had previously approved the use of deck blocks as footings for several decks in the subject area. The witness further reported, that it was his opinion that deck blocks are a viable building tool if located and installed correctly and further, to his knowledge, no decks constructed with a permit, using deck blocks, over his 15 years as a Building Official, had caused damage to the structures to which they were attached.

The Applicant maintained that there was little to no ground movement in the area on which his deck has been built. He further maintained that digging up the rock and clay soil under the deck would prove very difficult and unnecessary, as his previous deck had been constructed on the deck blocks without issue or damage to his home. The Applicant advised that as a compensating measure he had installed jacks at each of the deck blocks in an attempt to demonstrate to the Chief Building Official that any potential damage to the deck or house caused by ground movement could be mitigated by adjusting the installed jacks.

In summary, it was the Applicant's position that based on past practice, and the vast number of existing decks in Fort Frances constructed using deck blocks that have shown not to have caused damage to the structures to which they were attached, demonstrates that the use of the deck blocks as footings provides sufficiency of compliance with the Building Code.

4. Respondent’s Position

The Respondent submitted that the Applicant constructed a deck at the rear of his existing single family dwelling. He reported that the deck was attached to the house by way of a ledger board bolted to the rim joist of the existing house, and that the deck joists hang off the ledger board with joist hangers. He further reported that away from the house, the deck joists rest on a beam that sits on posts, which stand on concrete blocks placed at grade.

The Respondent submitted that the typical soil in Fort Frances is silty clay type soil, which is susceptible to frost action and movement. In support of this claim, the Respondent submitted a geotechnical report from a third party engineering firm. This report confirmed that the common soil type in Fort Frances was silty clay and further, that the frost penetration in unprotected areas such as roadways and parking areas could be as deep as 2.6 m.

The Respondent maintained that in light of the common silty clay type soil present in Fort Frances, the proposal to use concrete blocks as footings for the deck, is not in compliance with Article 9.4.4.4. of the Building Code related to soil movement or the requirements of Article 9.12.2.2. related to the minimum depth of foundations. The Respondent advised that the winters in Fort Frances can be severe and that the freeze/thaw conditions can cause movement of the soils, and as a result, a deck attached to a structure, without the proper foundation, could cause damage to a structure to which it is attached.

The Respondent submitted that when reviewing the Applicant's permit drawings, which proposed the use of the deck blocks, he had advised the Applicant that a minimum depth of 1.2 m below grade would be required for the deck's foundation for protection against frost movement and to satisfy the Building Code requirements. The Respondent reported that living in the area close to the Applicant; he has witnessed firsthand significant movement of the accessory buildings, located on his own property, each winter.

The Respondent submitted that he disagreed with the Applicant's position that the soils in the area are not susceptible to frost movement. He advised that in discussions with the Building Officials in Fort Frances and other communities in northwestern Ontario, through their own past experiences, they also agreed that this is not the case in areas with heavy clay soils.

In response to the Applicant’s argument that the past performance of deck blocks used in the area make them appropriate for the subject construction, the Respondent submitted that it was his opinion that the proposed construction of the deck’s footings, does not satisfy the Building Code requirements of Article 4.2.4.1. "Design Basis” for the design of foundations. The reason, the Respondent advised, is that the Applicant has not provided any evidence to demonstrate that this soil type at this location is different than what is typical in the area nor has he submitted sufficient evidence that the movement of his deck would not cause damage to the structure to which it was attached. Consequently, it is his opinion that a minimum foundation depth of 1.2 m is required.

In response to questions, a structural engineer, appearing as a witness for the Respondent, supported the Respondent's position that the proposal to use deck blocks for the foundation of the subject attached deck, does not comply with the Building Code and further, that a below grade foundation would be required for a deck built in this area that is attached to a structure.

In response to questions, a second witness, an engineer and Chief Building Official, stated that it was his opinion that a foundation depth of 1.2 m might even be insufficient due to the frost depth witnessed in the area. In response to questions, the witness indicated that he had approved the use of deck blocks where the deck was not more than 61 cm (2 feet) high off the ground and not attached to any structure. He concluded that in his opinion the Applicant's proposal does not comply with the Building Code.

In summary, it was the Respondent's position that in order for the subject deck to comply with the Building Code, it would require a below grade foundation to a minimum depth of 1.2 m due to the silty clay soil present in the area and due to the fact that it was attached to a structure.

5. Commission Ruling

It is the decision of the Building Code Commission that the use of deck blocks as the footings for the as-constructed deck, does not provide sufficiency of compliance with the technical requirements of Sentence 9.12.2.1.(1), Clauses 9.12.2.2. (7)(c) and (e), and Clause 4.2.4.1. (1)(c) of Division B of the Building Code at 1301 Emo Road, Town of Fort Frances, Ontario.

6. Reasons

  1. Article 9.12.2.1. of Division B of the Building Code requires that excavations for foundations to extend to undisturbed soil. Further, Sentence 9.12.2.2.(1) of Division B of the Building Code states, “Except as provided in Sentences (4) to (7), the minimum depth of foundations below finished ground level shall conform to Table 9.12.2.2.”

    Sentence 9.12.2.2.(7) states, “The foundation depths required in Sentence (1) do not apply to foundations for decks and other accessible exterior platforms,
    1. that are of not more than 1 storey,
    2. that are not more than 55 m² in area,
    3. where the distance from the finished ground to the underside of the floor joists is not more than 600 mm,
    4. that are not supporting a roof, and
    5. that are not attached to another structure, unless it can be demonstrated that differential movement will not adversely affect the performance of that structure.

    The Commission heard that the finished ground to the underside of the deck floor joists is more than 600 mm, and further heard that the as-constructed deck was attached to the house. Consequently, two of the five conditions contained in Sentence 9.12.2.2.(7) have not been satisfied. Based on the evidence and testimony provided, the Commission was not convinced that differential movement would not adversely affect the performance of the structure, therefore, it is the Commission’s opinion that sufficiency of compliance with Sentence 9.12.2.1.(1) and Sentence 9.12.2.2. (7) have not been achieved.

  2. Clause 4.2.4.1.(1)(c) states, “The design of foundations, excavations and soil- and rock-retaining structures shall be based on a subsurface investigation carried out by a person competent in this field of work, and on any of the following:

    in situ testing of foundation units such as the load testing of piles, anchors or footings carried out by a person competent in this field of work.”

    In this case, insufficient documentation and evidence was presented to demonstrate compliance with the requirements contained in Clause 4.2.4.1.(1)(c).

Dated at the City of Toronto this 5th day in the month of November in the year 2015 for application number B 2015-33.

Tony Chow, Chair

Yaman Uzumeri

Gary Burtch