Failing Timber Retaining Walls

Crosstie walls, timber walls, railroad tie walls and any other wood constructed wall may fail over time.  The failure may occur due to poor construction, poor materials or the wall has just reached it's life expectancy and needs to be replaced.  Often these walls are surrounded by structures, driveways, pools or other factors that make removing and replacing the wall practically infeasible.

How do you repair a failing timber wall?  Let's look at a couple of types of failure and briefly describe the solutions. 

Timber walls that are leaning but the materials are in good shape

For this type of wall, it may be poorly constructed (dead men are lacking or designed improperly) or the conditions have changed (floods, drainage, loading, etc).  In either case we are assuming the materials have several years of life expectancy and the main failure point is the retaining system.  In this case, helical tieback anchors can be used to support the failing wall.  In most cases we can cut through the wall, install helical tieback anchors and place steel plates on the wall.  This picture is what a tieback timber wall can look like after this type of repair.

 

Timber walls that are leaning or failing but the materials are bad or the access is bad.

When timber walls begin to lean and deteriote they often cannot be shored up because the life span of the wall and wood have reached their end.  For this type of problem, one solution involves installing helical tieback anchors (or soil nails) and then installing a concrete spray finish (shotcrete) on the exterior of the timber wall - thus creating a new wall.  Here a few photos to show the steps of this process.

 

Once the reinforcement has been installed with proper waterproofing behind the soon to be sprayed finish.  Once the finish is put on the finished wall can look more like.

If you have a situation where you have a failing timber wall there are several options to give a long term solution to this common problem.

Foundation Repair Contractor Reviews in Atlanta

There are many foundation repair companies in Atlanta.  Some state they have 20 years of experience, others say 20 years in business, and some don't say how long they have been around at all.

How do you know who you can trust, who has been around, and what the prospects are for the business to be around to warranty their work?  Great questions and one that is not that easy to answer.

When Atlas Piers of Atlanta was incorporated in 1989 there were 3 other piering companies in Atlanta.  Those other companies are no longer in business.  This model has happened year after year.  In just the past 3 years we have seen one long time company go out of business after the death of the owner, one national company leave Atlanta for business reasons, and a recognizable modular wall company who installed piers fold shop.  What happens to these warranties?

Earlier this year I had the chance (for the 2nd time in a week) to try to explain how a warranty works (or doesn't work) when a foundation repair company goes out of business.  This was a company that had given a 10 year warranty on the products they installed 3 years ago.  Unfortunately, the company went bankrupt and closed the doors.  Now the warranties are void and the homeowner, who was selling his home, was left to install another set of foundation piers in order to sell his home.  The previous companies piers seemed to be doing their job, but unfortunately with no warranty the buyers didn't want to take the chance.

Carefully read about each foundation repair company.  Do your research on Better Business Bureau, Kudzu and other review sites to find out about each company.  Many companies are "old" companies that have just gotten in to piering, while other companies are very "young" but have experienced people.  What does 20 years in business, 20 years experience, and we've been around for 20 years really mean.  There is one local company that tells people they have "been around" for 20 years.  The company they work for is less than 10 years old and the previous company (or two) they worked for/owned went bankrupt.  

Also be careful of companies who make their own piers.  Generally you can get a better price because there is no markup, but then there is generally a lack of quality control and you have increased your risk.  If something were to go wrong then having a company AND a manufacturer helps the homeowner, but if they are one and the same you have no where to turn (think of buying a car - if the dealership won't help then the car manufacturer may - but if the dealer is the manufacturer - well you see the point).

Settling and Sinking Foundations

If you are noticing your home gradually slanting to one side, you are probably aware that you have some foundation problems. However, there are some less obvious causes of foundation problems that will help you identify issues before your home structurally deteriorates.

Keep on the lookout for things like windows and doors becoming stuck or misaligned. Watch for cracks in basements, slabs, and on sheetrock walls in the living areas of the house. Water puddles that form around the base of your home may also indicate foundation problems, as can upheaval of floors or floors that gradually become sloped.

Upper level soils, 6 to 8 feet below ground level, go through wet and dry cycles due to seasonal moisture and temperature changes. When there are drastic changes like a heavy rain fall right after a drought, water moves through the soil at greater rates than normal. This water looks for the path of least resistance, if this path is through or under your foundation, settlement and cracks will start to appear. Soils with heavy concentrations of water can double in weight causing hydrostatic pressure to buildup against your foundation, or consolidate soils. This consolidation can cause your foundation to sink due to the lack of support.

Foundation repair products are designed to give new support to structures that have lost their original supporting soils. Like stilts these underpinning products will not only stabilize a sinking foundation but they also can lift and hold the structure at it's originally design elevation.

If you notice that your foundation is settling bring in a foundation engineer or foundation repair contractor to analyze your situation and recommend a solution to fix it. Foundation repair contractors work directly with engineers to carry out the engineers plan he has developed to stop your foundation from sinking.

How to Repair a Settling Garage Column - Part 2

In our first part of discussing Garage Column Repair - we talked about many misnomers about the garage column itself.  Here will talk about the ways of repairing the garage column and why some of them just do not work (no matter how good the salesman is).

You can dig a hole under the column and pour concrete:

This is about the worst thing a contractor can do.  The column is generally failing because there is too much weight for the soil to support.  Soil generally weighs around 75-100 lbs per cubic foot (for loose to medium soil).  Concrete on the other hand weighs roughly 150 lbs per cubic foot.  By adding concrete you may be adding additional weight (think of an anchor on a ship) an only make the problem worse.  In addition, now that you have poured concrete it only makes repairing the column more difficult in the future.

You can just pressure grout under the column:

Maybe - in most cases you are dealing with slabjacker or mudjacker who only pumps the grout directly under the slab and on top of the soil.  In this case you are doing the same thing that the concrete guy does.  Adding more weight under the column.  It may work in the short term but long term this is not the best idea.  And you will not be able to lift in almost all cases.

This contractor says he can install 1 push pier and fix the column:

From a price perspective this is very temping to homeowners, but the cost of this repair will be greater in the long term.  In order to install a resistance pier you use the weight of the structure to push the pier in the ground.  From an engineering standpoint you cannot install just one resistance pier unless you "overdrive" or over stress the building.  This is a problem waiting to happen.

I know you can install 1 helical pier and repair the column:

Maybe.  From a capacity standpoint, Atlas Piers could easily install 1 pier to support the capacity (most of our competitors cannot make this claim).  The problem can be two fold.  One, if the brick or column sticks out past the edge of the garage slab then this would be an issue for the bracket and pier assembly.  The bracket needs to go as close as possible under the load - so the farther the brick or column sticks out the less this happens - which only weakens the pier.  The second issue is the concrete footing now has to carry the garage floor (and cars) from the side of the garage to the center of the column (generally 9ft).

Lifting a garage column will only cause more problems:

If I were a company that couldn't lift - I would say the same thing.  We lift almost all of the failed structures (including columns).  Why stabilize when you can restore?

These are only some of the misnomers and ways to repair a garage column.  At Atlas Piers - our standard garage column repair consists of 2 helical piers and we can typically lift the column very close to normal.  When you consider what the results are - the price is very reasonable.

Garage Column Settlement Repair - Part 1 - Misnomers

We at Atlas Piers of Atlanta are constantly asked about repairing garage columns, the center column between two garage doors.  This article (along with the next one titled "Ways to repair a Garage Column") will help identify solutions and misnomers with repairing garage columns.  

Garage Column Settlement is normal:

All structures settle.  So this is both true and false.  The problem arises when your garage column (or any other part of your structure) settles at a faster rate, or continues to settle.  Properly constructed garage columns do not continue to settle.

Garage Column Settlement is not a structural problem:

If it carries a load, it's a structural problem.  All garage columns carry some sort of load from the framing and/or siding of the house.  The extent that it carries a load is the question, but yes the garage column is a structural component.

The column is done settling:

Says who?  It very well may be done settling, but unless you've done extensive soil testing or you are God - chances are you are just guessing that it is done settling.  Changes in water drainage, loading or even decomposition of organic debris can change the compaction and bearing capacity of soils.  Some columns continue to settle for 20 years after the house was built.

You can just patch the cracks in the brick and it will be fine:

The only thing for certain is that your brick will be patched.  You cannot even say that the brick won't crack again, because if the brick is cracking, it most likely means your column is settling.

I'm sure the builder put a footing or grade beam under my column:

We have fixed hundreds, if not thousands of garage columns over the years.  The one thing we know for certain is there is no certainty that your builder built it with a footing.  About 50% of the garage floors and columns we repair have some sort of footing.

Foundation Repair and Bowed Basement Walls

Do You Need Professional Help with Your Basement?

Has your basement become a source of worry over the years? Have you noticed water or high moisture content in your basement? Are you aware of the fact that weak or wet basements can actually cost you your home?

Basement wall foundations are the most important element of a stable home. However, often foundations fall victim to a number of factors and become weak and troublesome. Foundation walls and basement floors crack and bow due to external pressure soil pressure and seasonal changes.

In many areas like Georgia, where the soil is damp in nature and the climate is moisture-laden, it is evident that Georgia homeowners are constantly troubled with wet basements and cracked or bowed walls. With the hydrostatic pressure and expansive soil issues, foundations in Georgia homes weaken considerably over time.

Signs of Foundation Failure

You can identify that you need foundation repairs from the following signs that develop within a couple of years of initial foundation failure:

• · Windows and doors do not close easily
• · Floors are uneven
• · Gaps are created between trim and windows/doors
• · Interior wall plaster and basement walls develop cracks and fissures
• · Nail pops appear on the ceilings and walls
• · Bowed or leaning walls and chimneys
• · Sinking foundations

To counter these problems, many homeowners rebuild the damaged walls or floors of their foundation, or rebuild the entire basement. However, there are more effective and affordable options available to homeowners in Georgia today. We, at Atlas Piers of Atlanta take pride in providing you a cost-effective and financially feasible solution for fortifying your basement. We provide quality, long-term solutions that are advised by the most experienced and skilled basement repair experts and engineers in the country today!

What We Do!

Carbon Fiber Reinforcement – We use Stronghold brand carbon fiber reinforcing strips.  These strips epoxy to the surface of your wall to prevent further bowing and cracking.  The strips can be used when the wall is bowing less than 2” from plumb.  This installation is done within one-two days, with the help of our team of basement foundation repair professionals.

Helical Tiebacks – Heavy steel anchors are screwed into the ground and then attached to a heavy steel plate on the inside of basement walls. This installation is done within a couple of days, with the help of our team of basement repair professionals.

Push Piers – Robust heavy steel piers are hydraulically driven down to the load-bearing soil with high-pressure hydraulic equipment. Each pier is individually load tested to assure long term support of your basement walls. With all piers installed below ground level, the external beauty of your home is also left untouched. This installation is done within a few days, with the help of our team of basement repair professionals.

We install all these foundation repair systems at any time of the year anywhere in Georgia! Some of the cities that we serve are Atlanta, Roswell, Marietta, Sandy Springs and many others.

So what are you waiting for? Call us for a free estimate today at 770-740-0400!

Seasonal changes may cause problems with your homes foundation. Hydrostatic pressure or puddles of water may cause bowed, buckled or cracked basement walls. Rebuilding of the wall is not always necessary and generally doesn’t solve the problem but installing anchors and/or piers, along with solving drainage issues, can lead to long term success.

Generally installation is complete in a couple of days by our trained basement repair professionals without long term disturbance of landscaping. All anchors and piers are manufactured by Earth Contact Products from high quality steel and are hot dip galvanized for long life. The system is designed and engineered to develop holding strength several times the strength of a basement wall.

 

Not all Helical Piers are the same

the article below is a reprint from another foundation repair site.

 

From a distance, helical anchors from manufacturer to manufacturer look similar, but are they? In simplest terms – No they are not the same. As a matter of fact, there can be huge differences in helical anchors. Some suppliers use old oilfield pipe (known as J55 pipe) and this can make a huge difference in longevity and structural safety of the helical anchor.

First of all, the used oilfield pipe available for the helical anchor market is pipe that is deemed no longer fit to be used in the oil rig. With the high oil prices and the pipe shortages, the oil rig operators are wearing it out before they sell it.

Let's talk about salt water in oil production. Most of the existing wells in Texas, Oklahoma and the Midwest are classified as stripper wells. These are wells that produce a 90% / 10% mix of fluid on a daily basis. This means that if the well produces 10 barrels of oil a day, it also produces 90 barrels of saltwater per day. The affects of saltwater on steel pipe does not need explanation. Furthermore, periodically, acid is drawn down the wells to help the flow of fluids into the well bore. Once again, not much explanation needed.

Last but not least, the most destructive effect on oil field pipe is known as rod wear. Inside the oilfield pipe, which is known as drill stem, are the sucker rods. Now very quickly, a brief lesson on oil production. The pumping unit sits on the surface. Attached to the horse head on the pumping unit is the bridle. Attached to the bridle is the polish rod. Attached to the polish rod are the sucker rods. Down deep in the hole is the rod pump. To pump this fluid (saltwater & oil) out of the hole, the horse head, the polish rod, the sucker rods and the pump have to go up & down constantly. These rods, going down through this pipe are rubbing against something and that something is the used casing pipe (J55 pipe). Oilfield operators generally will not stop using this pipe until they have determined that 30% or more of the wall thickness is gone.

To spell it out, these super hard rods, rubbing constantly against the casing pipe, causes some very thin spots inside the pipe. So, pipe that was nice and thick when it was new, has salt-water corrosion, acid corrosion and very thin spots due to "rod wear". Does this sound like pipe that should be used to manufacture helical anchors that provide structural support?

Obviously not all helical anchors are the same. Manufacturers that use old oilfield pipe may be putting your structure at risk. Why would they do this? Cost is the only reason. New structural steel pipe cost a bit more but is certified to specifications and is designed to provide years of structural support. Not all helical anchors are the same, as a matter of fact, there are major differences between helical anchors.

Foundation Repair Information and Advice

This article reprinted from myfoundationrepairs.com 

 

Repairing potential foundation problems should be a priority for every homeowner. Foundation repairs prevent little problems from becoming bigger, keep your home safe, and protect the value of your property. Fortunately, foundation problems tend to develop and worsen slowly, giving you time to make a thorough evaluation and decide on the proper action for the repairs.

Foundation Cracks

Foundation wall cracks that are less than .064” wide typically do not leak. Any crack repair performed on these cracks is cosmetic only. Larger foundation cracks or ruptures do need to be addressed. These cracks are signs that you have, or had, foundation movement.Each type of crack gives you a clue to what is happening with your foundation. Stair step cracks, cracks that follow the grout lines between blocks or bricks, generally indicate settlement. Cracks that are wider at the top also indicate settlement. Horizontal cracks generally indicate bowing or inward movement. Repairing cracks and patching cracks should not be confused. Patching a crack is merely Band-Aiding a possible problem. Crack repair is much more involved and require special training and specialized equipment. Before structural crack repairs are performed contact a professional engineer for guidance.

Foundation Drainage

A common culprit is water accumulation in the soil around the foundation, which expands the soil and puts pressure on walls and foundation footings, causing cracks to appear. Check to make sure all gutters and downspout drains are in good working order, and that the soil around your foundation is properly graded—it should slope at least 6 inches for every 10 horizontal feet.

Most foundations are required to have a perimeter drain system that channels sub-surface water away from the foundation. The drain system is made of concrete tiles or perforated plastic pipe buried in a gravel bed. It usually drains externally (a pipe that opens onto a low spot in your yard), or connects to your sewer system.

It’s possible for this drain to become blocked, causing water to accumulate in the soil and putting pressure on your foundation walls. If you suspect a blocked perimeter foundation drain, seek the advice of a licensed foundation contractor. 

Buckled or Bowing Walls

A foundation wall that has tipped, bowed, or severely cracked requires substantial reinforcement to prevent further deterioration. Repairing basement walls from the inside is usually accomplished carbon-fiber mesh or wall anchors spaced 4-6 feet apart along the entire wall.

Carbon fiber wall repair involves placing vertical strips of high strength carbon fiber in a bed of an epoxy compound. These carbon fiber strips will strengthen the wall far beyond its original strength. While it will not straighten a wall, carbon fiber repair will greatly strengthen basement walls that have not bowed more than 2”. 

Wall plate anchors are also strengthen basement walls along with being able to straighten them. They consist of metal plates placed in your yard (installed by excavating), and metal wall plates on the inside of your foundation walls The plates are connected by steel rods that can be tightened to pull the wall back outward. Helical tieback anchors perform the same functions as wall plate anchors. Helical anchors have tremendous strength and require engineering calculations to install correctly. The largest difference between helical tieback and wall anchors is the amount of excavating required. Helical tiebacks require full excavation on the outside of the basement wall opposed to wall anchors that only requires spot excavation.

Professional Engineering

Trustworthy advice comes from a professional engineer. An initial visit should reveal the severity of your problem and tell you what to do next. In the end, you should get a written report that makes specific recommendations and lays out pros and cons of each option. If you need a complicated fix, you might want to hire the engineer by the hour to inspect while work is underway.

Using Carbon Fiber to repair Bridges in Georgia

Below is an article describing how carbon fiber is used to repair bridges in Georgia.  

From Tech Transfer Newsletter, Summer 2003 »

Repairs with High-Performance Materials Make Bridges Stronger, Last Longer

By Rick Deaver, Abdul-Hamid Zureick and Brian Summers

Field and laboratory studies in Georgia show that carbon fiber composites can be used efficiently and cost-effectively --increasing bridge strength and service life --with minimal or no disruption to traffic.

In the late 1950s, aerospace applications began to use carbon fibers to create high-performance materials with enhanced strength and stiffness, lightness, and heat dissipation. Carbon fibers are 8 to 10 times stronger than steel, but 5 times lighter, and the reinforced composite does not corrode like aluminum or steel.

For the past 11 years, European nations, Japan, and the United States have used polymer composite material technology for strengthening, repairing, and rehabilitating bridge components. The composite materials in bridge applications are either shop-manufactured or field-manufactured.

PROBLEM

Many U.S. bridges are near the end of their design life and require repair or replacement. Both options are expensive and cause disruptions and delays to road users. Finding cost-effective and better ways to extend bridge life while causing the least amount of traffic disruption is a necessity.

SOLUTION

Application of Carbon Fiber Fabric on Georgia SR 2

In 1996 the Georgia Department of Transportation (DOT), in cooperation with the Federal Highway Administration and Abdul-Hamid Zureick of the Georgia Institute of Technology, commenced field and laboratory studies to examine carbon fiber composite rehabilitation of bridges and to recommend design and construction guidelines. The laboratory studies involved testing rehabilitated full-size bridge decks, beams, and pier caps. Results from one study showed that, on average, rehabilitated cracked bridge-deck panels with carbon composites were 33 percent stronger than bridge decks without carbon composites.

Georgia DOT decided to evaluate the use of carbon fibers to repair highway bridge decks, caps, and girders. The first field study was carried out on the State Route (SR) 2 bridge over the Conasauga River Overflow, east of Ringgold in north Georgia. The two-lane bridge, constructed in 1957, is 350 feet long and has 10 piers.

Two contractors repaired six of the pier caps in the spring of 1997 using field-manufactured composites. One contractor used carbon-reinforcing fabric that weighed 9 oz/yd2, and the second contractor used a thicker, mechanically epoxy-impregnated, carbon-reinforcing fabric that weighed 18 oz/yd2. After surface preparation of the concrete, some epoxy injections, and spall repairs, the first coat of epoxy was applied, and the carbon fiber fabrics were mounted by hand.

In laboratory studies, the strength of the similarly repaired pier caps far exceeded the original strength by an average of 25 percent, and the anchor bolts yielded before any failure in the pier caps. Static load tests on SR 2 showed that the repair was effective in confining the concrete and in transferring loads. Laboratory tests also determined the optimal fabric wrapping patterns for the pier caps.

The repair on SR 2 cost $42,000 and was completed in 4 days without lane closures. An intermediate conventional repair would have cost $170,000 and required one week of lane closures and traffic controls. Eventually the bridge would have required replacement at an estimated cost of $700,000. The carbon fiber repair therefore has saved the bridge from repair with helper bents and has extended its service life by 20 years.

The second bridge repaired with shop-manufactured carbon composite is on Lee Road over I-20 near Atlanta; the 258-foot-long bridge was built in 1962. A quarry and several light industries in the area produced heavy truck traffic, causing moderate deck cracking. Most of the cracking reached full depth and likely would have developed into a severe condition. Only the worst deck section was repaired as preventive maintenance.

The surface area was prepared for the installation of shop-manufactured carbon plates 0.05 inch thick, 2 inches wide, and varying lengths. Cracks were not sealed with epoxy, so that the examiners could verify how long the repairs lasted. However, a two-part epoxy adhesive was applied to the plates, which then were hand-rolled into place under the deck. Data analysis later showed no significant changes in the crack openings.

This repair to only one quarter of one end span was completed in fall 1998 and cost approximately $4,000. Conventional repair would have involved partial deck replacement by hydroblasting to a depth of about 2.5 inches and then re-pouring the deck. This would have cost $290,000 and would have required 4 days of lane closures. The carbon fiber repair, if used on the whole deck, would require no lane closures and would cost $170,000 --saving $120,000.

APPLICATION

The study findings guided repairs to a bridge on SR 120 over Interstate 85 near Atlanta. In 1998, an over-height truck had damaged the bridge, exposing the reinforcement steel of the outside concrete girder.

The repair was made shortly after the accident and was completed within two days, at a cost of $33,000. The carbon fiber repair allowed the daily traffic of 30,000 vehicles to maintain full access to the bridge. Previously, a typical repair replacing the damaged beam would have cost more than $130,000 and caused a one-month (or longer) lane closure.

BENEFITS

The bridges repaired with carbon fiber composites and the findings from extensive laboratory tests under this research effort together demonstrate that this technology can be used effectively and efficiently for repairing and rehabilitating bridges. As a result of this research, Georgia DOT was able to use carbon fiber composites for an emergency repair on another bridge.

The advantages of this technology include:

• quick repairs,
• minimal inconvenience for motorists,
• little or no need for special or heavy equipment,
• an increase in bridge service life, and
• a reduction in bridge replacements.

The Georgia DOT Maintenance Office estimates that carbon fiber can be used on 20 bridges per year in Georgia. This strategy could save approximately $5 million per year, based on estimated replacement costs versus carbon fiber repair costs and assuming an average extended bridge life of 20 years.

Rick Deaver is Chief of Research and Development at the Office of Materials and Research, Georgia Department of Transportation.

Abdul-Hamid Zureick is Professor of Civil and Environmental Engineering at the Georgia Institute of Technology.

Brian Summers is State Bridge Maintenance Engineer at the Office of Maintenance, Transportation Management Center, Georgia Department of Transportation. 

This is an article from TR News, May-June 2003, Number 226, Transportation Research Board, National Research Council, Washington DC, pp.46-47.

Foundation Repair - Your Options

When choosing a foundation repair contractor you need to know what foundation repair product options you have to choose from. When it comes to foundation repair work on your home, there are several choices that need to be made. These choices range from using helical piers or steel push piers, waterproofing or underpinning, concrete segmented piles or steel push piers or even eccentric vs. concentric piers.

You will hear proponents for each different type of foundation repair underpinning system, you will also hear many different reasons why some steel push piers are better than other steel push piers. Wading through all of this information is the key to finding the right method and means of repairing your home. Here we will focus on the differences in piering systems, specifically eccentric piers verses concentric piers.

First we must define the terms eccentric and concentric. An eccentric piering systems is one who's pile axis is not in line with its applied load. A concentric pier is a pier bracket and pile who's axis is in line with the applied load.

Next you must categorize these piering systems. 

Eccentric Piers     Concentric Piers 

Steel Push Piers     Steel Push Piers

Helical Piers          Segmented Concrete Piers

Micro Piers            Hybrid Piers

 

Eccentric Pier Diagram 

For foundation repair applications, helical piers are always eccentric in nature. The helical sections are installed through the bracketing system from the side of the pier. Micropiers are also installed through the bracketing systems from the side of the pier. The major reason for this is the relatively large equipment used to install these types of systems cannot fit below the wall or footing.

Segmented Concrete Piles are installed directly below the footing and then a bracket or platform is installed on top of the pile to transfer the applied load to the pier. Hybrid piers are the latest concept in underpinning products. These pier systems generally use concrete filled steel pier sections installed directly below the footing and then either a steel bracket or concrete block is placed on top to transfer the load to the pier. These hybrid piers are marketed as the best of both worlds, in reality they are compromise of both worlds. They do not provide the full benefits of steel piers and they have the same negatives as the segmented concrete piles.

As noted above, steel push piers can be eccentric or concentric in nature. Each manufacturer generally determines which design best fits their manufacturing and design capabilities and sticks with that style. Only Earth Contact Products has successfully designed and engineered both types of systems for residential use.

What is better, eccentric or concentric? Well that is the $64,000 question. There is no real answer, because both, if designed properly and applied properly, will work well. While an eccentric designed pier requires more engineering and tighter quality control, not only can they work well but some have worked well for over 30 years. This is not to say all eccentric piers have good engineering behind them. Many are manufactured around cost constraints opposed to good engineering. Concentric steel piers are a lower tech solution that has many application advantages over its rival, the eccentric pier. They can be installed with less footing modification, they can be installed in lower headroom areas and they require less installation equipment to use.

 

Concentric Pier Diagram:

Concentric piers are great for crawl spaces due to the fact that a tall drive stand is not needed to drive the pier sections. For eccentric piers to be used in a crawl space you will need either a fairly deep crawl space or you will have to cut through the flooring to make room for the drive stand. Concentric piers are also not affected by deep brick ledges or other obstacles like their competition.

The down side to most concentric piers is in their lifting or stabilization of structures. Most concentric piers do not allow room for anything more than a bottle jack (car jack) for lifting. They are pressured up with the bottle jack and then simple shims are placed between the bracketing system and the footing, the footing is then lowered onto the pier system. Bottle jacks are very undesirable for a couple of reasons. First, the structure is over lifted to allow for the steel shims (similar to segmented concrete piles). Next, with bottle jacks, the installer has no way to measure or control the hydraulic pressure applied to the structure. Most engineers frown on the use of bottle jacks for structural repairs.

There is only one concentric pier available, that uses a hydraulic manifold lifting system and is continuously adjustable, on the market today. The Earth Contact Products Model 200 uses a hydraulic manifold system, the same system used on their eccentric push piers. This system was designed by engineers for engineers to allow for critical infinite adjustability and control in lifting structures. The Model 200 also uses a patented adjusting platform that does not require over lifting or shims. This unique combination has created large demand and acceptance of this particular concentric piering system.

As you can see there are many variables and styles of underpinning pier systems available. So how do you choose the one that is right for your home? This is the easy part. First, hire an engineer and let him help determine your foundation repair needs. Then take your new found knowledge out into the market and wade through the variety of foundation repair contractors and find one that installs a quality piering system that has been designed and engineered to perform on your home. No bottle jacks, no shims, no shallow installation methods, just good engineering and manufacturing by a quality foundation repair company. 

*Note: This article used by permission.  Written by Jeff Tully.