6 Drainage PROBLEMS you may have and not know about

Offering reliable landscaping services to homeowners in British Columbia since 2013

Picture of Sam Maerz

Sam Maerz

Owner/Site Foreman

If we haven’t met before allow us to introduce ourselves. We are Back 40 Landscaping and our expertise is in retaining walls, hardscaping and drainage. We also like to bring education to those looking for retaining wall and drainage solutions.

A basic drainage system has 3 components

  1. Land specifically sloped away from designated areas.
  2. A pair of pipes buried at the bottoms of your foundation called Perimeter and downspout drains. The perimeter drain pipe has holes in it to collect ground water, while the downspout pipe is solid so it doesn’t lose any water it collects.
  3. A discharge location with unlimited capacity for all of the water collected throughout every season.

Additional systems are available to drain lower grade areas, collect surface runoff from driveway and patios, handle water behind retaining walls, and drain any other place you can think of.

Problem 1: Not having at LEAST a basic 3-component system

  1. All properties are susceptible to not having properly sloped land away from structures. Most operators grade by eye, which leaves room for error. Near flat landscapes should be graded by laser to ensure water will only flow away from designated areas.
  2. Older homes and buildings are most likely to not have a perimeter and downspout drain systems. This mean that all of the water from the ground, and roof will be kept close to the home or structure. This can be problematic for basements, and crawl spaces as this water will create standing water, mold, an unpleasant musty smell, and rot if left uncorrected.
  3. New and older construction can all share the same challenges as to where all this collected water goes. Some streets may have a “Storm water” connection point provided by the city, while other may have a ditch system to use. In the case that neither of these options are available a leach field or rock pit may be used. HOWEVER, it must be built large enough as the Fraser Valley’s clay soil doesn’t dissipate water very quickly.

Problem # 2: Improperly built 3-component system

Site grading:

Even if it appears you have all 3 components, parts of it could be poorly designed, or installed. It’s very common for areas of a yard to be flat which prolongs the drying time after a heavy rainfall. In the past it was normal for an operator to grade by eye, but time after time operators got it wrong. With the advancements of lasers, sites are now laser graded to a perfect preset slope. Proper grades move water away from higher areas by using gravity; A scientific principle that doesn’t fail.

Perimeter and downspout drains:

Unfortunately, it’s all too common that perimeter drains and downspouts are tied into together. From the surface you would never know this, as they both use the same white pvc pipe. This allows all of the collected water from your roof to escape underground at the base of the foundation. Eventually the perimeter drain will collect this, but not before the water has made your foundation footer wet, and potentially entered your basement or crawl space.

Discharge area

All of the pipes around your building as well as any other drainage systems (French drains, retaining wall drains, driveway drains) should tie into what’s called a sump. This is usually a large 3-4’ diameter concrete container that sits flush in the ground. There are inlet pipes, and outlet pipes connected to the sump. The outlet pipes carry the water to its designated discharge area (storm drain, ditch, leach field, rock pit, pond, etc.).

The sump is a great connection point as well as a great debris filter. As rain falls on your roof asphalt shingles lose their granules. This makes its way to your gutters, and down the downspouts into your system. Without a sump collection area, this debris clogs pipes deep underground. Instead of having to clean or unearth pipes, the debris ends up in the sump, where it can easily be shoveled out as needed.

Problem 3: How difficult is it to add drainage after construction?

Site grading:

Regrading a site after finished landscaping has been installed is a big undertaking.

It’s not always the entire area, but whichever area needs to be regraded will be like starting over.

The process for this in a residential setting involves stripping, trucking and disposal of the grass, excavating the soil to raise and lower areas as to form a downward slope away from all structures.

Another method that does a much better job, and lowers disposal costs of the grass is to use a Harley rake. A Harley rake is a tractor attachment that is similar to a rototiller.

It chews up the grass and top 3” of the soil. It grades the soil, sorts rocks and debris all in one pass.

It’s almost automatic, eliminating operator error.

Perimeter and downspout drains:

Adding a perimeter and downspout drain system requires excavating down to the bottom of your foundation, this is often in the range of 2-8 feet deep and 3-4 feet wide.

Unearthing this area requires the use of an excavator and requires digging all the way around your building.

Large piles of soil the size of cars are placed away from the open area so workers in the trench are protected.

Temporarily placing this soil away from your home creates a wide working area that will affect grass, and any plants in the area.

Special care can be taken in certain areas such as around decorative concrete, trees, and valuable areas.

However, it’s important to note this is a major undertaking and extensive landscaping will need to take place afterwards.

Problem 4: The building code drainage systems are not enough

This is a very common issue that we see because of how much rain the Fraser Valley gets annually.

It’s an uncorrected problem in a lot of cases because of two reasons.

The first is that in most cases it is not required to be addressed when building a new home, and the second being its wrongfully accepted as something you just have to live with.

Here is a list of times you should add an additional drainage system.

  1. Non permeable soils: clay (retains water for longer)
  2. Wanting to use your yard sooner after a rainfall (mowing, playing, relaxing)
  3. Large surface collection area: Patio, driveway, parking lot
  4. Gravel driveways that wash or rut out
  5. Not practical to grade / slope yard away from structures and sensitive areas
  6. Nearby hill that is draining onto your property
  7. Neighboring property causing localized flooding
  8. Home / building that is lower than the surrounding area
  9. Older homes without waterproofed foundations
  10. Basement / crawl space in a high-water table area

Additional drainage systems can include:

  • French drains
  • Driveway drains / Channel drains
  • Collection sumps / Inlets
  • Drainage swales
  • Vegetation or Mulch to aid the soil in absorption

Problem #5: Problems with French drains

French drains are a fantastic way of bolstering your homes defense against water. They are a great add on solution IF built correctly.

A French drain is a U-shaped collection area. It is made by excavating the soil and lining the area with filter fabric, placing a drain pipe in the bottom and filling the trench back in with round rock. The top few inches can be filled with soil so lawn or landscaping can be grown on top.

The problems we see most often is these drains are:

  • Built with thin, low quality pipe which collapses shortly after burying
  • They are not built using filter fabric, so the surrounding soil clogs the pipes inlet holes, OR if they are built with fabric, the fabric is UNTESTED and doesn’t actually allow water to pass through it.
  • and in most cases the trench is backfilled with soil, and not round drain rock. This prevents water from easily entering into the system, and evacuating the area.

A properly built French drain will move a lot of water, and cost $5000 – $35,000 for a typical residential yard.

Typical process:

  • It is very common to use plywood to protect concrete and lawns from excavator damage.
  • Haul and dispose of excavated soil.
  • Line trench with tested filter fabric and a CSA rated drainage pipe,
  • Connect pipe to sump system or city storm connection
  • Cover pipe with clear round rock for maximum void space and water flow,
  • Finish by covering with soil for planting grass or flowers afterwards

Completely hidden from above a French drain maybe a perfect solution for you.

Problem #6: You can’t fix drainage when you need it

A complete drainage solution includes proper planning, excavation, building, grading, and finished landscaping. It is very difficult, and in some cases impossible to clean up a full project in winter.

Therefore, in order to have the best experience and limited interruption to your life we recommend bolstering your drainage systems between spring and fall.

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