Retaining Walls Offer Solutions to Landscaping Problems
© by Raymond Alexander Kukkee
Retaining Walls have been used for centuries to contain and stabilize steep slopes, to improve the appearance and utilization of limited areas in both urban and agricultural settings, and to improve safety. The ABC’s of retaining walls and how to build them are just as important today as they have been for centuries.
Areas of land that tend to subside, creep, or shift under load conditions may traditionally be left unattended or ignored as usable or unsafe for any practical building purpose unless they are first stabilized. Buildings cannot be constructed on unstable, creeping soil. Encroaching erosion and slumping lands can endanger existing buildings.Such are the practical uses of retaining walls.
Lands, Roadways and railroad beds are stabilized, lawns and marginal yard areas are made usable, and landscaped areas of stunning beauty can be easily created in the process. Areas where access was previously difficult or limited can be improved significantly -even become stellar attractions with simple planning and the careful construction of one or more retaining walls strategically placed.
Are Retaining Walls Expensive?
As in any construction project, there is cost, but with careful planning and moderate DIY skills, costs can be minimized. A contractor without ethics may recommend and an unnecessarily expensive retaining wall. In some conditions and situations, professional installation is recommended. Bottom line costs, material quality, type, and construction method should always be clarified with a fixed estimate prior to construction. Never pay more than a 10% deposit and obtain references; ask to see some previous jobs your chosen contractor has done.
For simple, low retaining wall projects, consider constructing a retaining wall using on-site naturally-available materials such as natural stone and timbers if available to increase the curb appeal of your property. There are several methods of building retaining walls with various materials listed below.
Modern technology, specially-designed retaining wall blocks, materials and designs allow other attractive options in both material and wall design for high-end, or more advanced, difficult projects where height, soil instability, or special considerations occur, such as being adjacent to a public sidewalk, roadway, or property line.
Construction of a retaining wall requires planning, thought, and work, but a correctly built retaining wall using both suitable and appropriate materials in the right application may be just the project your property needs.
Would you prefer a home that that has inaccessible, steep, eroded slopes covered with unruly vegetation, or choose a well-manicured property with a smartly-designed, attractively-built retaining wall ?
WHY DO I NEED A RETAINING WALL?
© by Raymond Alexander Kukkee
Most practical homeowners will quickly recognize why a carefully constructed retaining wall could be a beneficial project if ANY of the following conditions apply. Think about these:
- A piece of your lawn is so steep it has been allowed to grow wild and is even used for daring sports activities by all of the neighbours.
- Your yard is unattractive with irregular, rough, steep slopes, covered with unruly vegetation, weeds, untrimmed trees and long grass.
- Retaining walls been used to solve similar problem slopes on adjacent properties successfully. Their property looks great, yours looks terrible.
- Parts of your lawn are difficult or impossible to maintain. It is awkward, challenging, and too steep to mow grass safely. Vegetation is out of control. A retaining wall will make it easier to maintain those problem areas.
- You have no reasonable access to other parts of your property because of a steep, rough slope. A good retaining wall can provide an access corridor to previously inaccessible areas.
- The severity of slope is extreme. A safety issue –for both work and play. A retaining wall can make the area more user-friendly, much safer and reduce liability.
- Areas are totally unusable because of unstable ground, ground slump or slippage, water runoff and soil erosion. A retaining wall can be used to correct many problems including the natural destruction of grass areas by erosion.
If any of those conditions describe your property, carefully-designed retaining walls placed correctly can be attractive, functional, and offer better access and full utilization of the total area available to you whether it be a front, side, or back yard.
You can build a retaining wall using economical materials or natural materials commonly available in your location.
Retaining Walls Can Offer :
- Improved Aesthetics and Appearance
- Increased Safety with steep slopes eliminated
- Better Utilization of Space
- Improved ground Stability
- Increased Property Value
The BOTTOM LINE
A retaining wall may economically increase the usable safe yard area, making previously unusable areas accessible to the homeowner for lawn and garden, work, relaxation, entertainment or play.
A good retaining wall can be a great investment and offer great home value in return.
*A Casual Hint:
Using terracing with the installation of one or more less expensive, low retaining walls rather than a single, very high and expensive structure – is often an ideal solution that can create attractive, special purpose and usable stepped areas between individual or staggered retaining walls even on extreme slopes!
CONSIDERING PLANS, DESIGNS, MATERIALS AND METHODS
© by Raymond Alexander Kukkee
In a modern era that demands both aesthetics and utility, retaining walls must be attractive, functional and reasonable in cost to build. There are many materials and several methods you can choose from to build retaining walls that will meet your requirements, and can also be built within your budget. Materials are virtually unlimited in choice. Some may already be on your own property or close at hand, just for the asking.
MAJOR FACTORS To Consider in Building Retaining Walls
There are a number of major factors which must be carefully considered when planning to build a retaining wall, regardless of the design you choose.
- Is your design appropriate for the application? The average homeowner does not need an architecturally-designed wall for that 2′ high lawn edging. Equally, a very difficult environment may require a more sophisticated, or even an engineered solution.
- Materials must be carefully chosen for the application. There is little point in building a retaining wall with inadequate, poor quality, or the wrong materials, only to have it collapse from materials failure or wood decay in two or three years. Failures necessitate repair or replacement– once again, generating additional costs, wasting time, messing up the yard yet again–and unnecessarily disturbing the neighbourhood.
- Aesthetics-should be carefully considered. Although a sturdy, functional retaining wall 8′ high made of railway ties may do a wonderful job of stabilizing your front yard mechanically for many years, it may be considered an ugly eyesore in a high-end neighborhood.
- Beauty is in the eye of the beholder, so keep the neighbours in mind too. We are adamant that it isn’t necessary to keep up with the Joneses, but look around you. Be thoughtful and considerate of others. Make a note of the style of walls and materials in use next door and around the block. Doing so could save years of sore commentary, bad feelings and perhaps even the expense of rebuilding later.
- Is the size, height, location or style of retaining wall you need actually a project requiring professional engineering? Be realistic.
In a modern era that demands both aesthetics and utility, retaining walls must be attractive, functional and reasonable in cost to build. There are several methods you can choose from to build a retaining wall that will meet your requirements, –and can be built within your budget. Materials are virtually unlimited in choice. Some are even free.
You can build retaining walls with materials ranging from loose, flat stones to big rocks to timbers and railway ties but beware.
It is essential to select both materials and building method that are most suitable for your application. Taking extra care at the design stage can prevent retaining wall failure. Retaining walls eventually sustain damage from shifting, age, and weather. They can totally fail for a number of reasons including poorly selected materials, poor building methods, underestimation of the requirements of the structure, and other factors.
REASONS FOR POTENTIAL WALL FAILURE
Damage to retaining walls and subsequent failure or collapse of such structures after installation is a common problem. Damage and future collapse may be caused by a number of factors including:
- Lateral (sideways) soil pressure
- Vertical pressure (Weight of the wall itself)
- Stress induced by incorrect construction
- Vibration and impact (street traffic, seismic activity)
- Soil instability and creep
- Insufficient anchors or “deadmen” poorly designed support systems
- Friable, crumbling soils, inadequate, poorly built or insufficient footing area
- Water pressure buildup (static) usually caused by flood, heavy rainfall or underestimation of the drainage surface area involved, excess water from roof leaders .
- Poorly installed, plugged, or non-existent wall and footing drainage
- Frost Heaving: Inadequate footing depth
- Water penetration, freeze-thaw cycles of concrete block, brick, and poorly selected, porous types of stone
- Failure of reinforcing bar by corrosion, salt damage
- Decay and wood rot of structural members built of untreated wood
- Failure of fasteners. Fasteners may be undersized, forgotten, or badly placed.
- Structural members incorrectly specified. Such timbers are usually inadequate (under-specified for the application)
Common Building Materials Used For Retaining Walls
by Raymond Alexander Kukkee
Materials used in the construction of retaining walls are highly variable by location, cost, and availability. Consider these common materials, both natural and manufactured solutions, for your retaining wall application.
- Timbers : Squared timbers manufactured and available in various sizes, 4×4, 6×6″, 6×8, 8×8″ and larger. Usually pressure-treated for long life and commonly available.
- Logs: Natural logs can be used for a natural rural or western appearance, but should be cedar, locust, or another rot-resistant variety of wood. Logs should be peeled and treated to prevent deterioration from rot and insects.
- Railway Ties: May be new or used. Railway timbers are creosoted for long life.
- Switch Ties: Creosoted timbers that are railway-related, but are longer lengths. Offered in 10′, 12′, 14′ and 16′ lengths
- Concrete Block: May be typical, plain concrete building block or custom shaped, coloured and textured cement blocks specifically designed for retaining wall applications.
- Cinder Block: Block cast from cinder, lighter than concrete block. Not commonly available in some areas.
- Artificial Stone: Look-a-like “Stones” that have been cast in random shapes to imitate natural stone
- Natural Stone: Stone that occurs naturally in the environment. Stone used for retaining walls is usually limestone, a sedimentary or any other rock type that is easily split into flattened pieces. May be dry-laid or of mortared construction. Avoid porous stone if possible.
- Brick: May be burned clay brick or made of concrete. Clay brick is subject to moisture and is therefore less weather resistant and less durable than cement brick.
- Ballasted Concrete Blocks: Are specially designed, may be interlocking, but are hollow, lighter, and may be designed to be filled with crushed rock or coarse gravel for ballast.
- Cast concrete: Used by building a form as desired and pouring concrete. Should be reinforced with steel reinforcing bar for enhanced strength.
- Wire Mesh and Ballast Rock/Rip-rap: Roughly crushed angular stone, larger size 3-12″ and larger, Used along highways where ground and bank stability is problematic. Considered to be the least attractive option for the homeowner.
VARIOUS BUILDING METHODS
One of the most common materials for retaining walls is also one of the least expensive. Both new and used railway ties are commonly available across North America, the latter becoming available as national and private railways replace thousands of ties annually or substitute modern concrete ties. To build your retaining wall with railroad ties, go here.
Cinder blocks are tough, relatively light weight, and therefore can be easier to use than concrete blocks. Filling the hollows with ballast rock can provide additional weight if required in this application. Concrete blocks can be used in precisely the same manner. They are, however, much heavier to work with. To build with cinder blocks or concrete blocks, go here.
Pressure-treated landscaping timber is affordable and a good choice, being commonly available, light and easy to work with. Landscaping timbers are attractive and considered to be cleaner environmentally than creosoted railway timber. To build with landscaping timbers, go here.
A ‘dry’ or ‘mortarless’ retaining wall is assembled without using cement mortar, and is therefore free of the challenge of working with mortar or the expense of hiring a bricklayer. Because the mortar-free wall is also more flexible, it is unnecessary to pour a rigid concrete foundation. To build a mortarless retaining wall, go here.
A Geogrid reinforced retaining wall may be required where the ground is “slipping” or unstable. The application and inclusion of Geogrid fabric, when used correctly, not only stabilizes the slope but provides an anchor for the retaining wall itself in the process. Geogrid reinforcing is an excellent choice where where soil is loose and unstable. To build a Geogrid Reinforced retaining wall, go here.
If you need a retaining wall, why not build it of dry stone and turn it into an eye-catching, fabulous rock garden feature that provides much additional curb appeal ? This is how to do it. To build a dry-stone retaining wall, go here.
Got a yard full of huge boulders? Use this quick, eye-pleasing, but not so easy method to assemble them into a permanent, functional retaining wall. You’ll need a backhoe, power equipment, or 300 slaves with ropes for this project. For how to do it, go here.
Live next to an old stone quarry that has lots of reject, dimensioned stone? Use this inexpensive stone to build a retaining wall with timeless beauty. For tips on building with dimensioned stone, go here.
Is money no object? Retaining wall block design has come a long way in the last decade or two. These precast engineered blocks go together like toy Lego® set, except that a lot more exercise is required. If you’re doing a high-end retaining wall project, this may be the right choice for you. For building with precast, engineered interlocking retaining wall blocks, go here.
SAFETY ISSUES Encountered in building Retaining Walls
© by Raymond Alexander Kukkee
Safety is always a concern on any construction site. Construction of retaining walls is not an exception, even though it may be a small project. Always be careful and work safely! Personal liability may be involved if necessary precautions are not taken to protect passer-by, visitors, and onlookers.
On YOUR Retaining Wall Construction Zone, be AWARE that:
- Trenches : dug too deeply even in soil that appears to be stable can collapse without warning, causing physical harm or even fatalities. Take appropriate safety measures, cutting the sides of deep trenches back as recommended.
- There is always danger where excavators, backhoes or other heavy equipment is in use. Provide barriers for onlookers and always be aware!
- Keep children out of harm’s way at all times. Hint: Provide a safe and secure supervised “official”viewing area for curious youngsters.
- Avoid damaging existing infrastructure and buried Services : . Services such as gas lines, power lines or communication lines can easily be damaged and result in dangerous situations. Verify locations of all services prior to construction. Local utilities will gladly identify and flag locations of concern.
- Materials Handling: Wet concrete, stone, railway ties, and timbers are heavy. Use lifting devices and ensure you have adequate help where heavy lifting is involved. Worth repeating, stone, brick, concrete, and railway ties, and timbers are very heavy–especially when soaking wet.
- Safety Gear : Always wear safety footwear, gloves, and protective clothing. Wear approved goggles, safety glasses and a face shield when cutting creosoted wood or when sawing or breaking stone and brick.
- Stack building materials in safe, level areas prior to use. Never pile timbers, logs or railway ties on a slope. Rolling and sliding timbers can be deadly. Move them individually up slope as required and set them securely into place .
- Creosoted Timbers ! Caution! Be aware that cuts and slivers of wood from handling creosoted railway ties can cause slow-healing wounds because of the chemical nature of creosote.
- Slopes are slippery when wet, whether grass, mud, or gravel. Extra caution is warranted.
Above all, Plan for Safety, Work Safely and Be a Professional; remember, Safety comes FIRST.
Good to Go?
All done deciding what kind of retaining wall you want? Got the right materials, safety equipment and necessary help?
Now it’s time to go back to the how-to tips for the project of your choice–get out the shovels and call the helpers….it’s time to get to work! Or is it? Look at that sky!
Bad Weather Delaying your Project?
What about that weather? Wait! It can be problematic too! Black clouds are gathering and the rainstorm of the century is heading your way. Maybe you have just newly finished excavating 80 feet of trenching 3′ deep to install a footing for your retaining wall. You know you’re in trouble as the first raindrops hit and rivers of muddy water start running down the long slope into the trench … if only you had known. Planning can save you a lot of time, aggravation, and even doing the same work twice!
Always be informed and consider the weather before starting your project, especially if extensive excavations are involved and heavy rainfall is expected.
A heavy downpour in some soil conditions can collapse or even completely fill in a new excavation for footings. A judicious delay of a day or even a week for more favorable weather can be a very wise decision and save much duplication of work and additional expense.
Choosing the right timing for a big project can be tricky! Good luck with the weather!
*Hint: “Weather is not an exact science”, so if bad weather is expected, spend time planning your retaining wall project instead. Tomorrow is always another day….
RETAINING WALL TERMINOLOGY
©2008 by Raymond Alexander Kukkee
- Retaining Wall: Any structural wall that is installed to prevent soil from slipping downhill, or for aesthetic purposes to allow fill to be placed to create usable level areas where a slope existed naturally.
- Free-draining Back fill: Clean, uniformly-sized gravel or crushed rock that water will pass through quickly to promote drainage.
- Slope: Any surface area that is not level. Slope can be measured with a clinometer or a surveyor’s level and is expressed as a percentage ie. a 2 % slope, or in degrees, as in a “10 degree slope”
- Sleeper: A timber buried deeply, uphill and at right angles to the retaining wall, often connected to a retaining wall directly or by a cable to provide stability to the wall. Also called deadmen or deadman timbers.
- Deadmen timbers: are timbers buried at right angles to the retaining wall. Deadmen may be attached directly to the wall by building one end into a lower course, or attached from a distance using a galvanized cable. Also called “sleepers”.
- Switch timber: A long, creosoted timber ordinarily used in constructing switching systems in a rail yard but increasingly adapted to landscaping purposes including retaining walls.
- Railway ties: Short, heavy creosoted timbers used to construct railway tracks. Ties are the cross-bed timbers the long steel rails lay directly upon
- Foundation: A poured concrete base or compacted crushed rock located and built to carry the weight of a retaining wall or other structure. A concrete foundation may be reinforced with ‘reinforcing rod’.
- Reinforcing Rod: Special steel rod that is included in poured concrete structures to provide tensile strength.
- Tensile strength: Resistance to tension. Required at the bottom of a structure bearing much weight
- Compressive strength: Resistance to weight by compression.
- Ballast: Crushed rock, coarse gravel or stone used as a filler for weight in hollow structures.
- Rip-rap Very coarse 3 to 12″ (or bigger) crushed rock used for ballast and stabilizing of roadside and railway slopes.
- Geogrid Fabric: A fibreglass, plastic, or metallic woven mesh, used to stabilize loose ground.
Is that Incoming I hear?