Question 1

What water-cement ratio does the Code set for an Ontario patio?

Accepted Answer

The 2024 Ontario Building Code sets a maximum water-to-cementing-materials ratio of 0.45 for garage floors, carport floors and all exterior flatwork, under section 9.3.1.7(1). That is the Code number for exterior concrete. Whether that ratio binds a patio built without a permit is a different question. The City's list of projects not requiring a building permit includes landscaping, and the words patio, walkway and concrete do not appear on that list.

Question 2

Should my Orleans patio quote mention control joints?

Accepted Answer

Control joints are not mentioned in the 2024 Ontario Building Code sections we researched for exterior patios, and we found no City of Ottawa rule requiring them in a residential patio specification. That said, asking your contractor to describe their joint plan in writing is reasonable, and here is why it matters for your Orleans job.

Question 3

Should a concrete patio go over a septic area in rural Ottawa?

Accepted Answer

Placing a concrete patio over a septic system or its leaching bed is something we found no City of Ottawa concrete rule addressing directly, but it raises concerns under Ontario's septic and environmental rules that sit outside the scope of concrete flatwork. The short answer on the concrete side is: we found no City statement permitting or prohibiting it, and the decision is not primarily a concrete question.

Question 4

What base should go under a concrete patio in Kanata?

Accepted Answer

For a floor-on-ground, Ontario's 2024 Building Code sets not less than 100 mm of coarse clean granular material beneath floors-on-ground generally, though the Code says that layer need not be installed under slabs in garages, carports or accessory buildings. For a patio, we found no Code thickness or base depth requirement; the Code standard for exterior flatwork is 32 MPa concrete, and we found no statement on whether that provision binds a patio built without a permit.

Question 5

What should the base be for a hot tub pad in Kanata?

Accepted Answer

We found no specification in the 2024 Ontario Building Code for the base beneath a free-standing concrete pad, and no City of Ottawa rule that sets a gravel depth or base type for a hot tub pad specifically. The base depth and composition come from the contractor's written specification, and you should ask for those details in writing before work starts. That said, a few Code provisions are relevant context.

Question 6

Do I need a locate before digging for a patio in Kanata?

Accepted Answer

Yes, a locate is required before digging for a patio in Kanata. Under the Ontario Underground Infrastructure Notification System Act, 2012, anyone who digs, grades or excavates is an "excavator," and that includes a homeowner breaking ground for a patio. You cannot start digging until you have submitted a locate request and each member has responded. Submit the request through Ontario Dig Authority at least five business days before you expect to start.

Question 7

When can patio furniture go back on new concrete in Kanata?

Accepted Answer

We found no published source that gives a specific number of days or hours before patio furniture can go back on new concrete. The right answer depends on the mix, the weather and what the contractor specifies, so follow the contractor's written instructions for your particular pour. What the 2024 Ontario Building Code does say is that when the air temperature is below 5 °C, concrete must be kept at not less than 10 °C for 72 hours after placing.

Patios & Pads