It can be easy to forget your home’s rain gutters. They may seem solidly attached and appear to be doing their job properly, but are they? And incidentally, do you know what that job is?

Mission: protect your home

At first glance, everything may seem to be flowing along just fine:

  • The rain gutters (also known as roof gutters or eavestroughs) show no signs of leakage at their joints.
  • They are perfectly aligned.
  • There are no muddy splash stains on the foundation parging or exterior cladding at the base of the walls (which would indicate surface soil erosion).

All these are good signs. But they don’t necessarily mean that your gutters and downspouts are fulfilling their primary mission: to collect all water running off the roof and channel it a sufficient distance away from the house and thus protect the foundations from excessive groundwater pressure. Homeowners sometimes misunderstand this essential function, and neglect gutter maintenance.

A rain gutter must have one or more downspouts that direct water at least 2 m (6 ft. 6 in.) away from the foundations—into a drainage pit, for example. Otherwise, excess stormwater is likely to flow into the foundation drain.

When things stop working…

Overloading of the foundation drain results in the following problems:

  • Inside, humidity levels will rise, leading to discomfort, but also water infiltration and efflorescence (whitish deposits) on exposed concrete walls—or, worse, mould.
  • Outside, the soil near the surface of the lawn will be soaked.
  • The foundation drain system will also wear out prematurely: it can be infiltrated and clogged by fine particles or by ferrous ochre (in some sand-soil mixes that are rich in iron).

For more information on these issues, see the Tips & Tricks instalment Foundation drains: Problems and solutions.

Preventing problems at the source

Your house is a system, and roof gutters must properly play their protective role in that system. The following sections provide details of options you can consider to prevent problems at the source.

Plan A: Connect the downspout to a drainage pit

This method is very useful for ensuring that rain gutters are fully effective.

Also known as a dry well, drainage well, or soakaway pit, a drainage pit is an excavated section of soil partially filled with 20 mm (¾ in.) crushed stone. The pit is connected to the downspout by a length of underground pipe (make sure it is non-perforated). The crushed stone must be covered by geotextile membrane before being backfilled with soil and grassed over.

Eaux de pluiePDF file – 241 KB  (Source : City of Québec)

Conditions for installation

  • The bottom of the pit must be above the groundwater level.
  • The soil around the pit must have high water-absorption capacity.
  • The distance between the pit and the foundation wall must be at least 2 m (6 ft. 6 in.).
  • The pit dimensions must be calculated based on the volume of water that will be channelled there from the downspout.

In all cases, you must check with your municipality regarding the residential stormwater management standard—for example, compliance with lot lines.

Many municipalities strongly recommend that property owners install drainage pits. They cite the following benefits:

  • Less risk of problems for homes;
  • A reduced burden on wastewater treatment plants and municipal sewer systems;
  • Incentives to build in compliance with sustainability principles.

Plan B: Direct water from the gutters away from the house by other means

If a drainage pit is impractical, there are other ways to divert water from your rain gutters and channel it a sufficient distance away from the foundations—to a hedgerow, a vegetable garden, or a flowerbed, for example. These include:

  • Connecting a vinyl extender to the end of the downspout

This can be a rigid but flexible length of tubing, similar to a clothes-dryer exhaust hose. Another option is a length of plastic tube that retracts, but opens out as soon as water flows down the downspout (the mechanism is similar to that of a children’s party horn).

  • Installing a plastic or concrete diverter, also called a splash block

Water flowing out of the downspout strikes the diverter, which is placed on the ground, and splashes a sufficient distance away from the building.

  • When possible, extending the downspout by means of an elbow and sloping section that directs water farther away onto the lawn

A fence running away from a corner downspout can be used to support such an extension.

  • Connecting a downspout to a rainwater collection barrel

The water can then be used to irrigate flowerbeds, a vegetable garden, etc.

Gradual damage caused by water infiltration or repeated flooding is not covered by your home insurance policy. If your gutters are improperly installed and they cause, for example, mould that damages your home’s interior walls, you will not be compensated by your insurer. You will have to do the repairs at your cost. Another reason why preventing problems makes the most sense!

Our thanks to Vincent Boivin of Gouttières Boivin, a CAA-Quebec Approved Supplier, for his contribution to this instalment of Tips & Tricks.