Brick walkway in Mother Nature's Backyard. Laid in decomposed granite, this path is permeable to water |
Walkways,
driveways and patios are the second largest impermeable feature(s) in many
yards – second only to the roof. We’ve
discussed capturing roof runoff over the past three months (February-April
2013). This month we consider ways to
turn other impermeable features into rain-harvesting surfaces.
Many
Southern California homes have walkways, driveways and open patios of poured
concrete. This traditional style has
definite advantages: the surface is smooth, hard, durable and relatively
inexpensive. The main drawback (from a
water conservation standpoint) is that water runs off concrete rather than infiltrating into the ground. In addition, older concrete surfaces often
develop cracks and chips, making them less attractive and functional. As water becomes scarce, many of us are rethinking
our larger expanses of concrete and asphalt.
There
are more options today than ever before, whether you’re planning a new patio or
replacing an old walkway. New materials
and methods – and some older methods that are being ‘rediscovered’ - allow us
to create permeable surfaces that retain the benefits of older, impermeable
surfaces. The use of permeable surfaces is
gaining popularity world-wide, so you’re in good company if you’re
reconsidering your impermeable surfaces.
Next
month (June 2013) we’ll discuss the topic of garden water use more generally. We’ll
even provide a ‘Water Wishes’ questionnaire to help you to define water goals
for your garden. You
might want to read that posting before you continue.
Summer
is a great time for garden planning. With many garden chores at a low point, summer
provides time to research your options and even install new hardscape if
appropriate. Below we present a brief
overview of permeable hardscape. Much
good information on permeable surfaces exists on the internet, providing
further discussion, advice and details on installation. We’ve suggested some of our favorite sites
below, but there are many other excellent internet and print resources.
Must
I consider permeable options?
If
you like your current impermeable surfaces, consider capturing the runoff in a
rain garden or vegetated swale. Study
the drainage patterns; if the walk/patio was properly installed, the water may already
drain into your garden. If water currently ends up in the storm drain,
evaluate the feasibility of capturing it using a simple swale or rain garden
(see March and April 2013 posts). Alternatively, you might want to simply cut
down on the area. A smaller patio or
driveway – or one that combines both permeable and impermeable areas – may be
just the ticket.
Another
reason to retain impermeable surfaces is if your soil drains very slowly. You can easily determine your soil drainage
(see March 2013 posting). Most local
soils have adequate drainage; but if your soil drains less than an inch an hour
it may not be appropriate for permeable hardscape. You may want to work with a landscape
professional to improve the overall drainage and infiltration in your garden.
Permeable
Walkways, Patios and Seating Areas
Walkways,
patios and seating areas can be major living areas in our climate. We’re outdoors most months of the year and patios/seating
areas make this possible. Major
walkways and paths – like the walkway to the front door – get heavy foot traffic,
while other walkways likely get occasional use.
The first step in re-thinking your impermeable surfaces is to consider
their use:
- How often are they used/how much foot travel per
week? Could they be used more if
improved?
- Are they conveniently located (or are people
always using ‘alternate’ paths) ?
- Are they too small/narrow? Too large?
- What is good about them? What could be improved?
Time
spent in thoughtful planning and observation usually pays off handsomely when
designing a garden. Rethinking your
garden allows you to seriously consider just how well your garden enhances and
supports your lifestyle. Perhaps you
don’t currently have enough space for activities like outdoor dining. Or perhaps your entry walk is inconvenient –
or just plain ugly. Now may be the time for change.
Hardscape
features like seating areas and walkways play an important role in defining how
a garden looks. But they also facilitate
the use of garden spaces. Look
critically at your current hardscape – the good and the bad. What works well? What is frustrating? Re-thinking your hardscape allows you to
enhance what is good, change what needs improvement and even add new features
to make your garden more enjoyable and useable.
Several practical
considerations are important when re-thinking your impermeable surfaces. The most important of these are:
- Appropriate location: ease of use
- Safety
- Appropriate material/design for level of use
- Local building regulations and
ordinances/covenants
- Cost /ease of installation and maintenance
- Aesthetic considerations: style/material should complement and
enhance the house and garden
- Extra points: materials that are locally produced
and/or recycled
Locating
your pathways/walkways and seating areas for easy use is extremely important. The most logical location is often the one
that appears to be natural: the informal ‘path’ that everyone takes when
crossing the front yard; or the place
where lawn chairs end up on summer days.
When planning a seating area consider how it will be used. If access to electricity, water, the kitchen
or shade are important, plan accordingly.
Remember, rethinking your hardscape allows you to re-design it, making walkways
and seating areas more convenient.
When
considering a permanent patio, major walkway – or anything in the front yard –
review your local building codes, ordinances and/or covenants to be sure that
your plans conform to regulations. This is important whether you have a
contractor do the actual work or you plan to do it yourself. The codes/regulations are there for a reason
– often related to safety. Better to design
according to code than have to remove a structure built ‘not to code’.
Perhaps
the most important planning determinant is the amount and type of use your
walkway or seating area will need to support. All aspects of design – from width and slope
of walkways to the materials/installation methods used – impact the suitability
and safety of a hardscape surface. Major
pathways and heavily-used seating areas should provide a firm footing and be
easily traversed by all – including those with physical handicaps. Occasional-use paths (such as those providing
access for garden maintenance) can be less robust. The emphasis is on appropriateness and safety
for the amount and type of use.
The main
walkway to your house must provide safe, easy access. Check your local regulations – nearly all
municipalities have codes that cover specifications for major access paths and
driveways. The same is true for
paths/walkways in parking strips and verges.
A
surface that supports high level usage need not be covered with concrete or
asphalt. There are many good permeable options for high, medium and
low use areas; the range of materials continues to expand with increasing
demand. The options vary widely in their cost of
installation and maintenance; be sure to consider routine maintenance and
longevity when choosing a material. Some
materials and designs are best installed by an experienced professional while
others can be easily done by the home owner.
That may also figure into an
appropriate choice.
Arizona Sandstone and Brick Walkways: Mother Nature's Backyard |
Permeable
hardscape materials range from brick and stone to organic mulches. Some materials (brick, stone; some types of
gravel, crushed rock and pavers) are appropriate for more formal garden designs
while others (bark mulch or decomposed granite) are more informal in appearance. All
other things being equal, choose a material that complements the garden/house
in color and design; hardscape features (walkways and seating areas) have a
strong visual impact.
We’ve
listed the most common materials used in Southern California gardens – grouped
by use level - at the end of this article.
The list covers the costs, limitations and best uses for the different materials.
We hope you find this useful. You don’t necessarily need to use new; recycled
bricks, pavers, concrete chunks and other materials can sometimes be obtained
at low cost from Craig’s List and other recycling resources.
Arizona Sandstone in high-use areas of Mother Nature's Backyard |
In
Mother Nature’s Backyard we’ve installed several types of walkways. The more formal – and highly trafficked - central
areas of the garden demonstrate the use of brick (lead photo), Arizona Sandstone
(rock; photo above) and ‘urbanite’
(recycled concrete; photo below). These
materials differ in looks and cost, but all provide a firm surface that
infiltrates water well. All contribute to the semi-formal ‘look’ of
our central garden area.
'Urbanite' (Recycled Concrete) Walkway set in decomposed granite |
Professional mason lays Sandstone Pathway on a base of decomposed granite |
Our
brick, stone and urbanite walkways were laid on a bed of decomposed granite
rather than being mortared in on a concrete base (see above). This method – sometimes called dry-laid construction
– requires an under-layer (base) of construction sand, gravel and/or decomposed
granite which provides a firm base that will infiltrate water. The sand or decomposed granite is also filled
between the bricks/stones to hold them firmly in place, making a study and attractive
surface. To learn more about installing this
type of permeable walkway or seating area see:
- http://www.landscapeandgardentoday.com/How_To/SustainablePermeablePaverPatio.php
- http://www.youtube.com/watch?v=14ce0wzqzOo
The
lesser trafficked (and more informal) north part of the Mother Nature’s
Backyard garden features a path of decomposed granite (photo above) that also provides a firm, permeable walking
surface. The informal look of decomposed granite
complements the ‘natural’ look of this part of the garden. In areas that are even less frequently
accessed (for example, around the rain garden) our garden features ‘stepping
stones’ (photo below) and paths of
chipped wood mulch. These
surfaces are not as easy to traverse, but still provide useable access during
most of the year.
Stepping Stones of Arizona Sandstone: Use of single material adds visual continuity |
In
choosing the hardscape for Mother Nature’s Backyard, our primary consideration was
appropriateness for the level of use and safety. As a public garden, many areas of the garden
must be readily accessible – much like a front yard walkway. For these areas, we chose materials primarily
from the high/mixed use list, below.
A
secondary (but important) factor was aesthetics. Among the appropriate choices, we carefully considered
materials that looked nice but were also affordable. Garden visitors are surprised to learn that
our bricks were donated – for the price of hauling them away. The bricks add a striking visual note to the
garden entry and complement the greenery of the foliage; and the price was
right. Another surprise is the
appearance of our ‘urbanite’ walkway.
This path has the semi-formal look of native stone at about ¼ the price!
Like us, you might want to use more
expensive materials in ‘high visual impact’ areas and lower cost materials
elsewhere.
It’s
sometimes difficult to visualize how a hardscape project will look once
completed. Pictures on the internet can
be extremely useful and are readily available for many materials. Visit local gardens and take pictures of
ideas you like. Home landscaping books
from the library can provide a wonderful source of information. If you live locally, we urge you to visit our
garden for some hardscape inspiration.
We’ll be happy to answer your questions about pathways and seating
areas.
Permeable
Driveways
More people
are installing permeable driveways than ever before. There are several options available, most of
which require professional installation. The following resources will get you
started on the topic of permeable driveways.
- http://garages.about.com/od/buildingagarage/a/Permeable-Paving-Options-For-Residential-Driveways.htm
- http://www.sierraclubgreenhome.com/go-green/landscaping-and-outdoors/permeable-paving/
- http://www.houzz.com/ideabooks/query/permeable-driveway
- http://www.coastal.ca.gov/nps/lid/PermeablePavement-What'sitDoingonMyStreet.pdf
Suggested
Materials for Permeable Hardscape (walkways; paths; seating areas)
Suggested Materials for High and
Multiple Use Areas – These areas include driveways, parking areas, high-use walkways and
patios. All materials provide a firm
permeable surface.
Material
|
Costs/Limitations
|
Best Uses
|
Brick
|
Installation:
Moderate/
high
Maintenance: low/ moderate
Limitations: cost; more
complex jobs best done by professional masons
|
Infiltration: Low to high, depending on spacing
Best Uses: Tight brick
can be used for all residential needs; loose (dry set) brick is good for
areas less frequently used.
|
Decking
(wood or wood substitute)
|
Installation:
High
Maintenance: High
Limitations: Expense; usually needs replacing every 15-20
years. Wood substitutes (Trex, etc) are often plastics.
|
Infiltration: Moderate to high, depending on gaps between
planks
Best Uses: While
expensive, decks can provide a beautiful surface for outdoor seating, dining,
etc. Can be combined with other
materials.
|
Pavers
|
Installation:
Moderate
Maintenance: Low
|
Infiltration: Low to high, depending on gaps and degree
of slope.
Best Uses: Seating
areas & walkways. Easily installed/ repaired; lots of different ‘looks’ -
wide variety of shapes, sizes, and
colors.
|
Porous
Asphalt
|
Installation:
High
– must be professionally installed
Maintenance: Low. Need to
clean out pores with water occasionally.
Limitations: ?Shorter life
than regular asphalt.
|
Infiltration: Low to moderate.
Best Uses: Good
replacement for current asphalt driveways. Petroleum based and produces tainted
run-off.
|
Porous
Concrete
|
Installation:
High
– must be professionally installed.
Maintenance: Low. Need to
clean out pores with water occasionally.
Limitations: ?Shorter life
than regular concrete.
|
Infiltration: Low to moderate.
Best Uses: Can be used
instead of conventional concrete anywhere around a home.
|
Stone –
Natural, Recycled, or Manufactured
|
Installation:
Low
to high depending on the type of stone and base material.
Maintenance: Low/moderate depending on plants and/or materials used
to fill the gaps.
Limitations: Cost
|
Infiltration: Moderate to high, depending on size and
spacing.
Best Uses: Seating
areas, walkways. Usually laid on a
sand/gravel base; can sometimes be sunken into the soil instead, if soil is
well-drained and plants are planted between stones.
|
Recycled
Concrete (‘Urbanite’)
|
Installation:
Low
to moderate depending on source of ‘urbanite’ and base material
Maintenance: Low/moderate depending on plants and/or materials used
to fill the gaps.
Limitations: not quite as
attractive as stone – but not bad!
|
Infiltration: Moderate to high, depending on size and
spacing.
Best Uses: low-cost
alternative to stone – can be used in any situation where sandstone or other
stone might be used. If you are
replacing old concrete, recycle the
old concrete chunks in your own yard.
|
Paving
Grids / Permeable Paver Grids / Porous
Pavers/ Gravel Cells
|
Installation:
Moderate
Maintenance: Moderate to
high (if the grass has to be mowed and regularly irrigated).
|
Infiltration: Moderate to high.
Best Uses: Paving grids can be filled with gravel or
crushed rock to form a firm driveway or pathway. For lower-use areas they can be planted
with study grasses. Grids are plastic,
cement or cinder-block.
|
Suggested
Materials for Medium Use Areas (like the part of the driveway that is
driven on, but not parked on and the sides of houses; paths that get frequent
use) allow a greater flexibility in the materials used. Appropriate materials
include all those listed under ‘High and Multiple Use’ as well as those listed
below. Consider using locally-produced
and/or recycled materials where ever possible.
Material
|
Costs/Limitations
|
Best Uses
|
Crushed
Aggregate (Crushed Rock; ‘Crusher Fines’)
Crushed concrete
|
Installation:
Low
Maintenance: Low.
Limitations: May be tough
on bare feet/children and some consider it unattractive. Weeds can become a
problem.
|
Infiltration: High
Best Uses: Makes a
compacted walk or patio area - used extensively in Europe. Many grades
(particle sizes) & colors.
|
Pea
Gravel; Small Pebbles
|
Installation:
Low
cost for Pea Gravel; moderate cost for pebbles
Maintenance: Low.
Limitations: Does not
compact into solid surface. Weeds can become a problem.
|
Infiltration: High
Best Uses: Softer on
feet. Probably best for children’s
areas, utility areas, vegetable garden paths.
|
Decomposed
Granite (DG) including stabilized DG
|
Installation:
Low
cost; more expensive than pea gravel, mulches.
Maintenance: Low. Add more DG as needed (every 3-5 years).
Limitations: particles
stick to the bottom of shoes.
|
Infiltration: Moderate to high.
Best Uses: Casual/natural
appearance. Excellent for garden paths, casual seating areas, side yards.
|
NexPave
|
Installation:
Moderate
(higher than DG; usually professionally installed);
Maintenance: low
Limitations: must order
large quantity – best for large area; edges can erode
|
Infiltration: Little; water runs off the waxy surface
Best Uses: Good for
trails, paths in public areas or with moderate use.
|
Turf Block
(grass pavers) - concrete blocks with holes filled with soil and planted.
|
Installation:
Moderate
Maintenance: Moderate to
high (if the grass has to be mowed and regularly irrigated).
Limitations: Maintenance
|
Infiltration: Moderate to high.
Best Uses: Drive-over/non-parking areas of driveway;
utility areas that get moderate traffic.
|
Suggested Materials for Low Use Areas (such as garden access paths) allow for the most flexibility in choices. Any of the materials used in high- and medium-use areas can be used in low-use areas. In addition, common mulches make natural, environmentally appropriate choices for these uses.
Material
|
Costs/Limitations
|
Best Uses
|
Chipped Bark
|
Installation:
Low
Maintenance: Low
Limitations: Needs to be
renewed yearly; less easy to walk on than high- and medium-use choices
|
Infiltration: High
Best Uses: Casual/natural
appearance. Fine grade bark makes a good walking surface (medium to large grades can
be difficult to walk on – better used as mulch).
|
Shredded
Bark (‘Gorilla Hair’)
|
Installation:
Moderate
Maintenance: Low/moderate
Limitations: Moderately
expensive for mulches; needs to be renewed yearly
|
Infiltration: High.
Best Uses: Casual/natural appearance. A better walking surface than most mulches. Best in moist and non-windy areas.
|
Tree Chippings
|
Installation:
Free/low
Maintenance: Low
Limitations: Needs to be
renewed yearly; less easy to walk on than high- and medium-use choices
|
Infiltration:
High.
Best Uses: Casual/natural
appearance. Best for low-use areas
like access paths for garden maintenance.
Can be used as a mulch/mulch path.
|
Rock;
Pebbles; Lava Rock
|
Installation:
More
expensive than organic mulches
Maintenance: Low
Limitations: Cost; color
choice; hard to walk on if used alone
|
Infiltration: Moderate to high, depending on spaces
between rocks and surface below.
Best Uses: River rock
is not a good walking surface – better as mulch in windy, exposed areas. Can be used as decorative filler around
pavers, for walkway edges.
|
Recycled
brick chips, glass chip mulch
|
Installation:
May
be expensive
Maintenance: Low
Limitations: Cost; color
choice; hard to walk on if used alone
|
Infiltration: High.
Best Uses: Excellent
as accents in smaller areas, for example around pavers; many colors, sizes
|
Additional
Resources on Permeable Paving
- http://www.slideshare.net/cvadheim/permeable-surfaces
- http://www.seattle.gov/util/groups/public/@spu/@usm/documents/webcontent/spu01_006286.pdf
- http://www.houzz.com/ideabooks/query/permeable-path
- http://www.houzz.com/photos/patio/permeable-pavers
- http://www.sunset.com/garden/landscaping-design/great-patio-ideas-photos-designs-plans-00400000049429/page43.html
Feel free to add a comment below. You can also e-mail your permeable hardscape
questions to: mothernaturesbackyard10@gmail.com
|
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