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RETAINING WALLS

Walls can be used to increase the size of level areas or to create special terraced effect

Hilly terrain in Pennsylvania creates the need for retaining walls. Walls can be used to terrace slopes, and enlarge usable areas for outdoor recreation, patios, walks and driveways. Retaining walls are also used to define landscaped beds and retain mulch products.

Stone wall

Walls are commonly constructed with natural stone, timbers, or precast blocks. While railroad ties were commonly used in the past, their creosote content discourages present day use. Natural stone creates a beautiful wall, but building with irregular stone can rapidly discourage an amateur stone mason. 

natural wall stone on a pallet
Natural wall stone palletized for shipment

  
Precast wall stone has become more available in recent years, and provides homeowners and professionals with a uniform-sized product that is easier to build walls with than irregularly shaped stone. Precast products provide several color choices to match existing home construction and suit your individual taste.


 


WALL DESIGN & CONSTRUCTION CONSIDERATIONS

  • Really need it?  Don't build a wall unless you really need it. There's considerable expense with initial wall construction and most walls will eventually need to be rebuilt due to soil and wall movement. 

  • Got the muscle?  Wall stones and timbers are typically very heavy, so be sure you have the physical strength to handle a wall project. Wall construction is hard, heavy work for strong individuals in good physical condition. 

Natural boulder wall

  • How steep is your slope?  Proper wall design becomes more critical as slopes get steeper, and as drainage and soil conditions worsen.  Basically, the taller the wall, the more critical it is for proper construction. Extremely high walls need to be designed by an engineer. 

  • How's your access?  Wall construction usually requires the removal of large amounts of soil and fill, so be sure to allow for removal and disposal of this "fill dirt." It's not unusual to hit rock while excavating for a wall, so heavy equipment and a jackhammer may be required. Do you have good access for a backhoe to reach the work area? How much damage will excavation work cause and what will be involved with repairing damaged lawn areas? 

Garden Wall

  • Got storage space?  Walls need good drainage behind them. This requires the delivery, movement and placement of tons of 2b crushed limestone, or similar product, behind the wall. Do you have a place to store the gravel and a way to move stone into the work area? This storage space is needed in addition to your storage area for wall product. 

  • Using quality products?  More people than you know have made the big mistake of buying inferior wall products, primarily wood timbers that weren't properly pressure treated for soil contact. Some wooden "landscape timbers" will start to rot in 3 to 5 years, requiring their removal and replacement. Check guarantees.

  • White haze?  Unfortunately, some precast stone products begin to show efflorescence after a few years. Efflorescence is the growth of salt crystals, appearing as a white powder on the surface of some precast walls as well as other masonry products. While it can be easily removed with power washing, it will usually reappear within a year. 

Efflorescence on a precast wall
Efflorescence on a precast wall. Sometimes 
you'll also see this problem on brick walls


 


WALL CONSTRUCTION BASICS

  • A good foundation.  The foundation and first course of your wall is most critical. Most wall manufacturer's specifications call for excavating at least 12-inches below the ground surface, and tamping-in a layer of crushed stone for good drainage on firm ground. 

  • First and foremost!  How well you lay your first course of wall stone or timbers determines how well the rest of the wall will turn out, so take your time and do it right! 

  • Pancake batter?  ...no, wall "batter." For every 4 feet of vertical wall height, it's usually recommended that your wall "lean back" 1 foot horizontally. This keeps some of the wall's weight against the slope, helping to hold back the slope. Many of the new precast wall products have wall batter built into the product, helping you step the wall back as it is being built. 

  • Deadmen tell no tales...  In timber wall construction terminology, a "deadman" is a timber tie-back into the slope to help maintain the wall's structural integrity. The more deadmen you use, the stronger the wall becomes, so don't scrimp. 

  • Watch your back!  Whether you're lifting wall stones, timbers, or shoveling crushed stone, practice proper lifting techniques. If you aren't physically able, consider hiring a professional.

  • Need a fence at the top? High walls should have a fence or other barrier along the top to prevent someone from falling over the edge and getting hurt. 

Fence along the top of a high wall
An aluminum fence along the top of this wall
acts as a safety barrier to prevent falls


VIDEO
HOW TO: Build a timber wall

 


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