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Retaining Walls – Books & Publications
Segmental Retaining Walls
Segmental Retaining Walls
There are many parts of the nation that are blessed with level or slightly sloping ground. Other parts are hilly and mountainous. If you want to make a hilly area flat, you need retaining walls. This simple building practice has been around for thousands of years. Farmers in southeast Asia have incorporated retaining walls for years to grow rice and other staples on hillsides. The retaining walls allow them to create steps or flat areas as they climb a hillside.
We tend to use retaining walls here in the USA to create level play areas, parking areas or terraces in a yard or garden. They can be as simple as a two foot high stacked rock wall or a highly engineered poured concrete wall 40 or 50 feet tall.
Construction Materials
You can build a retaining wall using any solid material. Earth is used as a "retaining wall" or dam to hold back lake water; wooden timbers are used in garden landscaping. Concrete, concrete block and stone are used effectively as common retaining wall materials. The newest and most interesting materials, however, are segmental retaining wall systems. These building materials are individual concrete block masonry units that are made to stack and interlock with one another. They require no mortar to hold them together.
These segmental systems can be used to create a two or three foot wall, or a wall in excess of 25 to 30 feet. They can be installed either by a homeowner or by a professional. However, walls in excess of four feet high should be designed or engineered before installation. Why, you ask? Well, it has something to do with wedges and weight.
The Sliding Wedge
The fill material behind a retaining wall is anything but stable. If it were stable, the wall would be unnecessary! Each backfill material (soil type) has its own angle of declination. This is the angle at which it would normally develop if left to weather. In other words rain and gravity would pull a certain amount of this material down. Retaining wall engineers call this material the sliding wedge. The mass of material gets wider at the top as the height of the wall increases. This means that the higher a retaining wall is, the stronger it must be.
This relationship, however, is not on a one to one basis. In other words, a retaining wall eight feet tall is not just twice as strong as a wall four feet tall. The eight foot wall needs to be four times stronger!
Batter but no Cake.....
Traditional retaining walls and the new segmental walls can be battered. This term refers to a backwards tilt. If you decide to build a retaining wall plumb, you are maximizing the sliding wedge of material behind the wall. If, instead, you tilt the wall back towards the hillside, you reduce the amount of material in the sliding wedge by an amount equal to the degree of tilt.
Segmental wall systems take advantage of this opportunity. In fact, many manufacturers of these products offer you different degrees of batter.
Year Round Material
Segmental wall systems allow year round construction possibilities. We already discussed that mortar is not required between the masonry units. And rarely are thick concrete footers required. The block wall usually rests on a level bed of gravel. These requirements mean that these walls can often be built in the dead of winter. As long as you make sure the ground below the wall is not frozen, you can usually proceed. Traditional materials require special protection so that freezing weather does not harm the poured concrete or mortar between stones or block.
Design Possibilities
Curves, stepped terraces, serpentine walls, steps, waterfront walls and plain old straight walls are a breeze with the new segmental retaining walls. Each manufacturer makes a wide variety of special interlocking blocks that allow you to make just about any shape you desire. Blocks of different colors are sometimes available. This allows you to incorporate a design or colored bands within a wall system.
Weight - BIG Differences
Not all of the segmental blocks weigh the same. This may impact you if you decide to build a wall yourself. Some wall blocks are heavy because they are solid or nearly solid. Other manufacturers use a hollow block that you fill with gravel as you construct each course.
These hollow block are as strong as solid block. The gravel fill, especially angular gravel, actually helps to interlock the blocks with one another. In addition, the gravel inside the block provide a quick way for water to exit the wall system.
Segmental walls are here to stay. These new mortarless systems can work for you. I suggest you give them serious consideration.
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Segmental Retaining Wall Manufacturers
Segmental Retaining Wall Manufacturers
- Allan Block
The Allan Block system incorporates lightweight blocks that are filled with gravel. They are ideal for homeowner projects. They also have a full line of different blocks and systems. The blocks are manufactured by independent distributors to rigid specifications. - Anchor Wall Systems
- Keystone Retaining Wall Systems
The Keystone system incorporates a more solid block that uses fiberglass pins to interlock the blocks. You can adjust the batter or setback of the wall system by inserting the fiberglass pins into different holes. - Loffelstein
This is the original segmental wall from Europe. It is widely available throughout the USA. - RisiStone Retaining Wall Systems
This is a Canadian product. These blocks interlock using a cast tongue and groove configuration. - Versa-Lok
The Versa-Lok system uses nearly solid block and fiberglass pins.
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Retaining Walls Construction Tips & Suggestions
Retaining Walls - Construction Tips & Suggestions
Planning
Before you even begin to build or design your retaining wall you need to get a handle on the site, soil conditions, water drainage patterns and final grading. These elements play a critical role in the actual design of the wall system. Make a drawing or sketch of what you have and take it with you to the local company that sells your block system. Numerous 'before' photos of your yard would be of great value as well. Take them from multiple angles so that you can communicate just how your yard looks.
Design
Now is the time to plan exactly where your wall(s) will go. This will allow you to determine the height and the wall's batter as well. Quite possibly you will need to develop terraces to make your plan work.
Most of the manufacturers have great design guides. However, I found Allan Block's to be one of the best. It is available on their web site for free downloading in a PDF file. Most of the other manufacturers also have some type of design guide on their site. Perhaps you will find that the diagrams of one are easier for you to understand. All of the guides offer fine color diagrams and cross sections.
Construction
Segmental retaining walls begin at the lowest part of your lot. A trench is required in order to install the gravel base to a sufficient depth. The gravel also is the leveling medium. You install and compact the gravel in a level fashion so that the wall will be level side to side. If the courses of the wall begin to bury themselves into a rising slope, that is no problem. You simply begin a new trench as soon as the first row disappears below grade.
As each course of the wall is installed, you install the gravel backfill and compacted earth. An old mason taught me how to keep the gravel and dirt separated. Simply use a piece of plywood that acts as a form. Position gravel on one side and dirt on the other. After you install the materials level with the top of the block course, lift the plywood up. Compact the materials and start with your next course.
This popular column was shared in the March 29, 2011 AsktheBuilder Newsletter.
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Lights Dim When AC Comes On
At 11:28 PM on 8/21/2004, Ron Elliot asked me:
DEAR TIM: I built a new home about two years ago. I have the electrical pole next to my barn, not next to the house. The pole has a transformer, meter and a 200 amp service. I had the contractor dig a trench (200 ft) from this pole to the house. This is how the electrical service comes to the house. Each time the air conditioning unit comes on, I notice a slight dip in the lights within the house. The electric company that supplies power says its because the pole is not adjacent to the house. I do not believe this, can you shed any ideas as to why my lights dip when the air conditioning unit kicks in. Thanks.
Ron Elliott
DEAR RON: Air conditioners, refrigerators, freezers, furnaces, etc. that have large motors require enormous amounts of power when the motor first starts to spin up to speed. I am talking huge amounts of energy. Once the motor is spinning, the energy requirement drops way down.
This instantaneous need for motor shaft speed is what causes that momentary dimming of your lights. AC units come equipped with start-up capacitors. These give the motor an electric boost when it first starts up. But over time, these capacitors can get weak and become ineffective. Eventually the power draw can become so enormous, the actual circuit breakers protecting the wiring to the units can pop from the current.
Your air conditioning system may also be overcharged with too much refrigerant. When this happens it puts lots of stress on the compressor and in turn the motor when it tries to get the compressor engine moving.
Relocating the pole would do little to solve the problem. I would ask your AC service man to look to see if your AC unit is overcharged or if it needs new start-up capacitors.
Tim
I received this email on 12/05/05:
DEAR TIM: The answers to this problem can also be that the conductors pulled in by the homeowner are too small to prevent the voltage drop being created over 200 feet. The problem could also be with additional homes having been added to the high voltage lines. That will also cause the dips. If surges get serious enough it can affect modern day electronics.
Eric David
Forensic Electrical Specialist
Whole House Surge Protection
Whole House Surge Protection
Whole house surge protectors that connect to your electric panel are generally tougher to find. The two primary sources are your local utility company and supply houses that sell electrical equipment / supplies to electricians.
I located one manufacturer of these important surge protection devices. They are Panamax. They make a very compact - yet effective - surge protector. They have two versions of the same protector. One has the wire leads that come out the back of the unit and the other has side outlet connection capabilities.
The two devices offer UL 1449 clamping voltages of 500 volts. The total joules available are 1,920. The units have an audible alarm and warning lights. They also offer a $10,000 connected equipment warranty AND a generous labor allowance in the event of catastrophic failure. I have connected one of these units on my electric panel.
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Surge Protector/Suppressor Protection Guide
Surge Protector/Suppressor Protection Guide
Wait till you study the table below! You already know that if you want protection, you need joules. There is a wide variance in the amount of joules for each surge suppressor. The all important clamping voltage is fairly consistent in many of the models, but the joule rating is all over the map.
Sears has everyone beat hands down. They have an affordable suppressor that has all the bells and whistles AND offers a 2,500 joule rating! It is also affordable with a retail price of $59.99. These suppressors offer the highest protection of all the ones I could readily find. If you can't get a Sears suppressor, the Belkin top-of-the-line model will give you great protection as well.
| Manufacturer | Model # | Joules | UL 1449 Clamping Volts | Alarms | Connected Equipment Warranty | |||||
| APC | Power Manager | 480 | 330 | Yes | $25,000
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| APC | Pro 7 | 320 | 330 | Yes | $10,000
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| Belkin | F5C895TEL | 1,950 | 330 | Yes | Unlimited
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| Belkin | F5C795 or TEL | 1,650 | 330 | Yes | $50,000
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| Belkin | F5C595 or TEL | 905 | 330 | Yes | $15,000
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| Electricord | H1566-006-WH | 1,350 | 330 | Yes | $50,000
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| Electricord | A-1548-006-BL | 800 | 400 | Yes | $15,000
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| Power Sentry | 374 | 1,020 | Not listed | No | $50,000
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| Power Sentry | 177 | 520 | Not listed | No | $25,000
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| Sears | . |
#83540 | . |
2,500 | . |
330 | . |
Yes | . |
$10,000 |
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Surge Protector Manufacturers
Surge Protector Manufacturers
Recently, I attended the 1998 National Hardware Show in Chicago, Illinois. I saw numerous surge suppressor vendors displaying product. Most of the suppressors were low powered units. I was shocked to see some of these inadequate units being marketed as OK for computers and such. They simply had way too few joules to do any good. I have listed below just some suppressor manufacturers / sellers (Sears).
You may find a great surge suppressor on a store shelf that I have not listed. You are looking for four things as far as I am concerned: A joule rating near or in excess of 2,000, a UL 1449 clamping voltage of 330 or less, an audible and visible alarm if the suppressor has been exhausted, and a generous, enforceable connected equipment warranty.
You should also read the fine print on many of the packages. Some manufacturers will replace their units if they fail in the field. All you need to do is make a simple phone call. You may need to keep some paperwork. If you are organized, this should be an easy task. Pay attention to the length of the surge suppressor power cord. Some come with a generous length such as 6 or more feet. This can come in very handy. Look for surge suppressors that protect your phone equipment and cable TV equipment as well. Call the following manufacturers and get some literature right now!
- American Power Conversion (APC)
877-272-2722 - Belkin
800-223-5546 - Pacific Electricord
310-532-6600 - Panamax (Whole House Surge Protector)
800-472-5555 - Power Sentry
800-852-4312 - Sears
Simply drive to your local Sears store!
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Surge Protectors
Surge Protectors
Computers, printers, fax machines, stereos, calculators, copying machines, you name it - if it has an electric cord, it very likely has one or more computer chips that control some function. Chips are everywhere and they are multiplying like rabbits. They make our lives less complicated but when a chip burns up because of a voltage surge, our lives can become miserable about as fast as the surge roared down the power line.
Small Spaces
One reason electric surges are becoming more of a problem is because computer chips are becoming more efficient. In other words, the distance between the electrical pathways on the chips is shrinking. This means that it takes less electricity to arc across the borders between the pathways.
Surges are also becoming a problem because of the deregulation of the electric industry. Electric utility companies are now having to deal with electric coming from many different sources. This wasn't such a problem years ago when just your electric company generated power. If they needed more juice, they would simply make the buy and prepare for the delivery. I believe it is much more complicated today with the net result being an increased possibility of electrical surges sneaking into your local electric distribution network.
CLICK HERE to get FREE & FAST BIDS from local electricians who can protect your home from surges.
Lightning and Ground Wires
Lightning strikes near your house or in your neighborhood can cause all sorts of problems. The huge voltage surge can travel down electric lines, telephone and cable TV lines. This rush of current is hunting for a place to go. It wants to go to the ground, but if it can't get there quickly enough, it will search out and destroy things in its path until it does find adequate pathways to the ground.
You can stop much of this damaging current with protection at your electric panel. This protection may include a surge protector, sacrificial lightning arrestors, oversized grounding wires and ground rods to dissipate the massive quantities of electricity. Think about it - imagine trying to drain a swimming pool through a drinking straw. That is not a good fit. Standard sized ground wires work fine for regular dead fault short circuits. They are no match for the massive amounts of amperage / voltage contained in a lightning strike. Never, ever underestimate the power of Mother Nature.
Plenty of Protection
If you want solid protection for your household electronic equipment, I feel you need to install two levels of protection. A whole house surge suppressor will absorb many - if not all - surges that originate outside your home. The point-of-use surge protectors that connect behind your computer and stereo will do that as well. They will also capture larger surges the might originate inside your home.
The surge suppressors you buy must have the highest joule rating possible. These ratings represent how many metal oxide varistors (MOVs) are inside the suppressor. The MOVs are sacrificial. Each surge no matter how large or small eats away at the MOVs. Eventually, the MOVs inside the suppressor will be destroyed. You want as much protection for as long a period as possible.
Super Safety
I have always been a Doubting Thomas. I have used surge protection equipment for years, but in the event of electrical storms, I always unplug my protector from the wall outlets. This automatically isolates all of my computer equipment from any possibility of damage.
I suggest you think about doing this as well, especially if you plan on leaving your house for vacation or some other reason. It seems to me that this plan offers the highest level of protection. I know what lightning can do as my house suffered a strike or near strike 10 years ago. We came home and all of the smoke detectors were blaring, the garage door openers were fried, the VCR was toasted, 5 circuit breakers were ruined, and all of the GFCI outlets were burned up as well.
Connected Warranties
Virtually every surge suppressor sold today comes with a connected equipment warranty. This is good coverage, but be sure you know what is covered and how you can make a valid claim. I urge you to create a file folder that you keep all product packaging, receipts, instructions, etc. You may need these things to make a claim.
Also keep in mind what the warranties don't cover. Think how many hours you might have invested in electronic files on your computer. You need backup data storage for this, not a warranty! Don't forget, tapes in computer tape backup drives can be fried if they are left inside your computer!
CLICK HERE to get FREE & FAST BIDS from local electricians who can protect your home from surges.
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