Question 1

How big must foundation drain tile be under Ontario's Building Code?

Accepted Answer

Ontario's Building Code requires foundation drain tile or pipe to be at least 100 mm in diameter (clause 9.14.3.2). The pipe is laid so its top sits below the bottom of the floor slab. Butt joints are left open between 6 mm and 10 mm. The pipe must be covered on the top and sides with at least 150 mm of crushed stone or other coarse clean granular material, where no more than 10 per cent of the material passes a 4 mm sieve (clause 9.14.3.3).

Question 2

Are foundation drains present in every older Ottawa house?

Accepted Answer

No, foundation drains are not present in every older Ottawa house. The City of Ottawa says that in some older homes they may not be present at all, and in others they may exist but be connected to the sanitary or combined sewer rather than the storm sewer. Ontario's Building Code (clause 9.14.2.1) requires drainage at the bottom of every foundation wall that encloses the building interior, unless it can be shown to be unnecessary.

Question 3

Can a granular layer under the footing replace drain tile in Ontario?

Accepted Answer

Yes, Ontario's Building Code provides an alternative to drain tile at the base of the foundation wall. Instead of perforated pipe surrounded by stone, clause 9.14.4.2 allows a granular layer at least 125 mm deep placed under the footing and extending at least 300 mm beyond its outside edge.

Question 4

Will Ontario's Code allow a dry well where Ottawa groundwater sits high?

Accepted Answer

Ontario's Building Code permits a dry well for foundation drain discharge only where natural groundwater is below the bottom of the dry well, and the well is at least 5 m from the foundation (clause 9.14.5.3). If groundwater in your area sits high, that first condition cannot be met, and the Code does not allow a dry well. What the Code requires instead Where a dry well is ruled out, clause 9.14.5.1 says foundation drains must discharge to a sewer or a drainage ditch.

Drain Tile & Foundation Drains

How big must foundation drain tile be under Ontario's Building Code?

Are foundation drains present in every older Ottawa house?

Can a granular layer under the footing replace drain tile in Ontario?

Will Ontario's Code allow a dry well where Ottawa groundwater sits high?