Spring thaw basement flooding in Ontario

Why spring is the risky season

Several things happen at once in an Ontario spring:

• The ground is frozen or already saturated, so meltwater runs across the surface instead of soaking in
• A winter’s worth of snow melts in a few days when temperatures jump
• Rain falls on snow, adding its own volume and speeding the melt
• The water table rises, pressing against foundation walls and up under the floor slab
• Ice blocks the way. Frozen downspouts, eavestroughs and discharge lines send water to the wrong places.
• Storm sewers and ditches are overloaded, and catch basins may still be buried under snowbanks
• Rivers and creeks rise, sometimes with ice jams

A basement that stays dry all summer can take in water during these few weeks.

How the water gets in

• Through cracks in foundation walls and the floor
• At the joint where the floor meets the wall
• Through window wells that fill up
• Over the sill of a basement door or walkout
• Up through the floor drain, when sewers are surcharged
• Into the sump pit faster than the pump can remove it

Before the melt: outside

Move the snow. Shovel snow back from the foundation, a metre or more where you can, and especially away from window wells, basement doors and the low side of the house.

Clear a path for the water. Open a channel through snowbanks so that meltwater can reach the street or the swale.

Find the catch basin. If there is a storm drain in front of your property, clear snow and ice from the grate.

Check downspouts. Make sure they are attached, extensions are in place and the outlets are not frozen or buried. Water should discharge at least a couple of metres from the house onto ground that slopes away.

Check the sump discharge line. A frozen or buried outlet makes the pump run without moving any water. Clear the end of the pipe.

Look at the eavestroughs. Ice-filled troughs overflow next to the foundation.

Clear window wells of snow, ice and leaves.

Before the melt: inside

Test the sump pump. Pour a bucket of water into the pit. The float should rise, the pump start, the water level drop and the pump stop. Listen for the check valve closing. If the pump is old or noisy, replace it before you need it.

Consider a backup. Power cuts and spring storms go together. A battery backup pump, or a water-powered one where permitted, keeps the pit emptying. A high-water alarm warns you early.

Check the backwater valve, if you have one. It should be clean and move freely. See backwater valves in Ontario.

Get things off the floor. Use shelves and plastic bins. Move valuables and anything irreplaceable upstairs.

Know where your shut-offs are, including the electrical panel.

Clear the floor drain so that water on the floor can leave.

Check your insurance now

Different kinds of water are insured differently, and the endorsements have to be in place before the loss.

• Overland water: surface water and overflowing rivers and lakes entering the home
• Sewer backup: water coming up through drains and the sump
• Ground water: seepage through the foundation is often excluded, though some insurers offer coverage as part of a broader water package

Ask your broker which you have, and what the limits and deductibles are. Coverage availability depends on your address.

During the thaw

• Walk round the house daily and look for ponding against the foundation
• Keep channels and downspout outlets open
• Check the basement, including behind stored items and in the corners
• Listen for the sump pump. One that runs constantly is working hard. One that is silent while the pit is full has failed.
• Avoid heavy water use during peak flows if your area has combined sewers or a history of backup

Many Ontario conservation authorities issue flood watches and warnings for their watersheds. If you live near a river or creek, sign up for alerts.

If water gets in

1. Stay out of standing water until the power to the basement is off. If the panel is in the wet area, call your electricity distributor.
2. Work out where it is coming from. Clear water seeping at the walls is ground water. Dirty water at the floor drain is a backup, and is contaminated.
3. Photograph it.
4. Call your insurer or broker.
5. Start removing water if it is safe, or call a restoration contractor.
6. Move what you can to dry ground.
7. Do not wait to dry. Mold begins within one to two days on wet drywall and carpet.

Full steps: what to do when your basement floods.

If it happens every spring

Repeated seepage means the drainage around the house is not coping. Longer-term fixes, roughly in order of cost:

• Regrading so that the ground falls away from the house
• Extending or redirecting downspouts, and disconnecting them from the sewer where the municipality allows or requires it
• Repairing foundation cracks
• Installing or replacing a sump pump, with a backup
• Installing a backwater valve
• Repairing or replacing weeping tile and waterproofing the foundation from outside
• Interior drainage systems where exterior work is not practical

Several Ontario municipalities offer subsidies for backwater valves, sump pumps and downspout disconnection. Programs, amounts and eligibility change, so check your municipality’s current terms before starting work.

More: basement flood cleanup.