Skip to content
You are here > Home > Your Ministry > Ontario Building Code > Appeals & Approvals > Building Code Commission > Rulings of the Building Code Commission > 1998 > BCC Ruling No. 98-29-634

Follow us

BCC Ruling No. 98-29-634

Email this page


IN THE MATTER OF Subsection 24 (1) of the Building Code Act, 1992.

AND IN THE MATTER OF Articles and Article of Regulation 403, as amended by O. Reg. 22/98, 102/98 and 122/98 (the "Ontario Building Code").

AND IN THE MATTER OF an application by Ms. Wendy Leach, home owner, London, Ontario for the resolution of a dispute with Mr. Rocky Cerminara, Chief Building Official, City of London, Ontario to determine whether the existing sewage system with a working capacity of 6,819 Litres/day serving the proposed renovated house with a total finished area of 819.9 m2 provides sufficiency of compliance with Articles and of the Ontario Building Code at 1880 Kilally Road, London, Ontario.


Ms. Wendy Leach, home owner
1880 Kilally Road
London, Ontario


Mr. Rocky Cerminara
Chief Building Official
City of London


Mr. Roy Philippe (Chair)
Mr. Doug Robinson
Mr. Frank Wright


Toronto, Ontario


July 29, 1998


July 29, 1998


Mr. Archie Leach
London, Ontario
Agent for the Applicant

Mr. Robert Palin, Director
Upper Thames River Conservation Authority
London, Ontario
For the Respondent


  1. The Applicant

Ms. Wendy Leach, home owner, has applied for a building permit under the Building Code Act, 1992 to construct an addition on an existing, detached dwelling at 1880 Kilally Road, London, Ontario.

  1. Description of Construction/Site Description

The Applicants are proposing to renovate an existing 2 storey, Group C occupancy, dwelling unit with a current finished area of 573.2 m2 (6,167.6 ft2). The proposed construction will add a further 246.7 m2 (2,654.5 ft2) to the residential structure for a total finished area of 819.9 m2 (8,822.1 ft2) . The proposed house will contain five bedrooms and 38.5 fixtures units. The renovation will add a limited number of extra fixture units. The estimated daily design flow is 8,699 L/d.

Regarding their sewage system, the Applicants are proposing to use the existing one for the renovated house without modification. The existing system is a conventional, gravity-based Class 4 system consisting of a 6,819 litre septic tank with a 232.3 m2 (2,500 ft2) leaching bed containing nine absorption trenches, comprising a total of 137.2 linear metres (450 ft). The trenches themselves are .92 m (3 ft) deep and are filled with 19 mm (3/4 in) stone. The distribution pipe is 3 in. trade size in diameter.

The site is flat. A spring runs across the property. The soils are described as gravel and sand material with some silt. The percolation rate was measured at 2 min/cm. The topsoil is approximately 30 cm (12 in) deep.

  1. Dispute

The issue at dispute between the Applicant and Respondent concerns whether the existing septic tank with a working capacity of 6,819 L/d serving the proposed renovated house with a total finished area of 819.9 m2 provides sufficiency of compliance with Sentences and of the Ontario Building Code. Sentence sets out how to determine the design flows of a sewage system. According to the Table found in this provision, the calculated daily design flow for the proposed renovated house would be 8,699 L/d. Sentence stipulates that a septic tank must be designed so that it can accommodate at least twice the calculated daily design flow. This requirement would mean that the septic tank would need to have a capacity of 17,398 litres. The current, and proposed septic tank, has a volume of 6,819 litres.

  1. Provisions of the Ontario Building Code

Sentence System Design Flows

(1)For residential occupancies, the total daily design sanitary sewage flow shall be at least the value in Column 2 as determined from Table (See Appendix A.)

Sentence Tanks

(1)The minimum working capacity of a septic tank shall not be less than twice the daily design sanitary sewage flow, except that in no case shall the working capacity of the septic tank be less than 3,600 L.

  1. Applicant's Position

The Applicants submitted that the existing septic tank, as well as the entire sewage system, has functioned without known problems. As they noted, the soil conditions are excellent. The Applicants argued that the existing system has adequate capacity and that the sewage flows will not change as a result of the renovation because a limited number of additional fixture units are being added.

It was their contention, in fact, that a larger tank may not function properly. They felt that the water may stagnate in the tank and would not flow into the existing leaching bed properly. They feared that this may cause harmful gases to escape, or would at least create a nuisance by the excessive odour.

In their view, the existing system, including the septic tank satisfies the intent of the OBC and would adequately serve the enlarged house.

  1. Respondent's Position

The Respondent submitted that when considering both Sentences and of the OBC the septic tank for the proposed renovated house should have a working capacity of 17,398 litres. Since the proposal sought to allow an existing system with a 6,819 litres tank to continue to serve the new structure, they refused to issue a building permit. The Respondent also added that the system required under the Building Code would probably be too large to service the proposed house.

  1. Commission Ruling

It is the decision of the Building Code Commission that the existing septic tank with aworking capacity of 6,819 litres serving the proposed renovated house with an addition of approximately 246.7 m2 provides sufficiency of compliance with Article of the Building Code provided that additional septic tank capacity of 5,000 litres is provided.

  1. Reasons

i)The current tank capacity is only subject to modification when Clause of the Building Code applies, because of the size of the addition.

ii)Articles and of the Ontario Building Code contain requirements for residential dwellings with an increase in finished floor area of 246.7 m2. The design sanitary flow is increased to be 2,467 L/d requiring an additional 4,934 litres of septic tank capacity.

iii)The increased septic tank capacity to accommodate the addition as outlined in Articles and is significant (approx. 83% increase in capacity) and no alternative proposals or supporting data was presented for consideration by the Commission, other than only a guest room and additional 8 plumbing fictures were to be added and that the existing system is working.

iv)It is the opinion of the Building Code Commission that the increase in septic tank capacity will improve the quality of the septic tank effluent.

Dated at Toronto this 29th day in the month of July in the year 1998 for application number 1998-37.

Mr. Roy Philippe, Chair

Mr. Doug Robinson

Mr. Frank Wright