Structural

Structural repair Denver – Our structural foundation repair division handles projects from $100 to $500,000. No job is too complicated for us to repair. Foundation access by machine or by hand, crawl spaces, attics, and basements can all be overcome. We can lift houses, level floors, and roofs by installing both wood and steel beams.

At Executive Structural Piering LLC we consider ourselves a complete structural repair company.   From complete new foundation construction to minor foundation repairs.  We are capable of repairing foundation that are cracked and have bowing walls.  Installation of  tie back helical pier systems.  Determining where water leaks are impacting your foundation wall and installing drain systems.  Both machine and hand installation of helical piers is possible. We can lift houses!! Bring them back to level even when they have moved more than 16 inches.  Brick, block, old concrete, wood, tile, rock, or poured concrete the construction of the foundation does not matter.  We have the skills and equipment to repair what ever your foundation is made of.  Don’t be fooled by foundation repair company’s that try to sell you on a video and some type is “special” repair process.  What they install may not be the best repair for your foundation.  At Executive Structural Piering we install and are capable of completing all different types of repair systems.  Ask us to prove it.  Do you have engineering already completed?  You can email it to us and we will be happy to provide you with an estimate. Don’t be over charged by a contractor who tries to scare you in to thinking your house is going to fall down.  Get several bids to protect yourself.  Executive Structural Piering LLC works up and down the front range.  Denver, Arvada, Golden, Littleton, Lakewood, Wheatridge, Westminister, Thornton, Federal Heights, Brighton, Broomfield, Boulder, Niwot, Erie, Loveland, Longmont, Greeley, Parker, Ft Collins, Winsor, Highlands Ranch, Parker, Aurora, Centennial, Englewood, Cherry Hills, Evergreen, Central City, Blackhawk, Lafayette, Superior any city normally with in an hours drive from our office.

Pop Tops

Pop Tops – Why go OUT when you can go UP?  Look in to what will give you better value for your money.  Who knows maybe creating a basement from a crawlspace will get you what you need. Either way Executive Structural Piering is the company to do it for you.

Pop Tops! Check your foundation!  You may discover that putting an additional on your house will cost you more than adding a second floor.  Costs to pop the top of your house can vary but normally it is cheaper than an addition.   With the new zoning rules many cities are adopting new restrictions that are limiting what homeowners can do.  Set back requirement are restricting how close the homeowner can build their house to the property line.  Many area’s are only 5′ on the side of your proerty line and as close as 10′ at the rear of  your property.  Front set backs vary from city to city.  With limited space the options the homeowner now has caused them to look at area’s of expansion that they had not considered before.  Call Executive Structural Piering LLC to install that master bedroom suite you always wanted.  We can handle all structural aspects of your pop top project.  Foundation old and damaged?  We can underpin the foundation to support the new weight of your pop top.  We work in Denver, Arvada, Golden, Littleton, Lakewood, Wheatridge, Westminister, Thornton, Federal Heights, Brighton, Broomfield, Boulder, Niwot, Erie, Loveland, Longmont, Greeley, Parker, Ft Collins, Winsor, Highlands Ranch, Parker, Aurora, Centennial, Englewood, Cherry Hills, Evergreen, Central City, Blackhawk, Lafayette, Superior any city normally with in an hours drive from our office.

Historical

Expert historical restoration company.

Many times inexperienced contractor try to make these types of structural repairs without having the knowledge to do it correctly.  We are called after the structural has failed and the homeowner needs a contractor who has the expertise to repair these historical buildings.  We will take the time to preserve and restore your historical building back to the original structurally sound building.

Historical Buildings.  At Executive Structural Piering LLC we take great pride in restoring historical building.  We are general contractors licensed in just about every city around the Denver metro area.  If your project is commerical or residential we have the ability to complete it for you.  We carry workers compensation and general liaibiity on all projects.  Sub contractors are not normally used to work on your project, we use employees only.  Start times and completion dates are provided for all projects.  Many other construction companies find it easier to tear down these beautiful building but we prefer to save them.  Make sure you  choose a contractor that has the experience to work on historical buildings.  Many contractor will say they have been in the construction business for many years but will not say how many projects they have completed on historical buildings.  Can they complete proper shoring?  That alone is one of the most important aspects of structural work on historical buildings.  Just by not shoring the structure correctly extensive damage can occur.  Framing and construction standards were not the same back then so experience is necessary to make sure the structure is shored correctly.  No project is to difficult for us to do.  When you want the best foundation repair company to work on your project make sure you contact us. Over 25 years serving Denver, Arvada, Golden, Littleton, Lakewood, Wheatridge, Westminister, Thornton, Federal Heights, Brighton, Broomfield, Boulder, Niwot, Erie, Loveland, Longmont, Greeley, Parker, Ft Collins, Winsor, Highlands Ranch, Parker, Aurora, Centennial, Englewood, Cherry Hills, Evergreen, Central City, Blackhawk, Lafayette, Superior any city normally with in an hours drive from our office.   Call us for all of your historical buildings structural needs.

New Construction

Our goal is to make any addition look like it was an original part of the house.  

Services Performed:

• Full excavation for the new addition foundation
• Foundation
• Framing
• Beam installation
• Siding
• Roofing
• Window installation
• Fascia
• Soffits
• Doors

New construction – Executive Structural Piering LLC can be your contractor to complete your new construction project.  We are general contractors licensed in just about every city around the Denver metro area.  If your project is commercial or residential we have the ability to complete it for you.  We carry workers compensation and general liability on all projects.  Sub contractors are not normally used to work on your project, we use employees only.  Start times and completion dates are provided for all projects.  Want to save money on your project.  You can be the general contractor yourself.  We can excavate or you can.  We can install the foundation or you can.  We can frame your house or you can.  Any aspect that you think you can handle on your own is fine with us.  Just need someone to oversee your sub contractors to make sure they are doing things the right way, we can do that to. Since we do not use sub contractors ourselves all finish work is completed by other companies.  Saving you money on your entire project.  Make sure you get several estimates for the work you need done.  There is no reason to over pay for your project. From dormers to additions to complete new foundations, we can complete any new construction project you may have.

Foundation Cost by City

Most Expensive Cities

Property owners in the San Francisco-Oakland, California metro area pay the most for house foundation issues.

 

 

 

Piering costs

different costs for different piers

Tie-back costs

costs associated with tie backs

Pier Installation

Helical pier installations:

Helical pier installation of Pile Power LLC Piers should be completed by qualified installers only. Ultimate pier failure could occur if a proper installation criterion is not followed.  (Installation of helical piers is to be completed using a torque head. Torque head should be well maintained and serviced on a regular basis.  Information from the manufacture should be available to determine motor and gear efficiencies. Pressure gauges should be testing and or replaced on a regular basis. Gauge tolerances must be accurate with 1%).  Torque will be continuously monitored and recorded throughout the installation of each pier. Each pier section shall be recorded reflecting pier section length and any additional notes regarding installation conditions. Pier location and identification shall be documented as piers are installed. Such information should include; project name and location, date, weather conditions, torque head used, a site map reflecting pier placement, starting psi and finishing psi and any notes regarding installation conditions.

For small shaft piers, there is a direct relationship between installation torque and pier capacity. Continuous monitoring or torque during installation will provide the installer with a profile of the underlying soil conditions.

Piers installed, for the purpose of compression, should be installed based on the hydraulic pressure curve of the torque head. During and ideal installation, the torque values should be constantly increasing, indicating that the pier is being inserted into more dense soil. If a drop in torque is recorded, it is most likely that a soft layer (such as soft clay) was found. The pier must continue to be inserted past the soft layer until a more dense soil (i.e. higher torque) is found.

Refusal will be determined by no vertical movement of pier depth. Auguring of pier may be required in order to penetrate very hard layers of clay stone. Vertical drop, even of only 1/8″ per rotation, shall continue for either a depth into hard clay stones of 2’ min or until refusal.

An empirical method has been derived and used in the screw anchor industry for many years. Installation torque is used to calculate the ultimate capacity of the screw anchor. The average torque achieved during the last three (3) to five (5) feet of installation is directly proportional to the ultimate axial capacity of the pier.

Colorado State University conducted a three-year study (1995-98) on the migration of water along helical piers shafts. The result indicates no more water penetration along the shafts of helical screw piles than along the sides of drilled concreted shafts.

The starter section of the piers is cut to a 45 degree angle in order to assist the installer in targeting the pier during installation.

Bearing and Uplift Capacity

For a single helix pier, the total resistance is derived from shaft and bearing resistance (see figures 5.1 and 5.2).

Single Helix in Cohesive Soil (Ф = 0 condition) ^{1, 5}

Compression:

                         Q_{c           =} A C_u N_c + π d H_eff α C_u                                                          

            Where:

                         Q_c        = ultimate pile compression capacity, (kN)

                         C_u        = undrained shear strength of soil, (kPa)

                         A_H       = area of the helix, (m²)

                        N_c        = dimensionless bearing capacity factors (due to pier diameter: N_c = 9)

                        d          = diameter of the shaft, (2.875 in = 0.073025 m)

                       H_eff       = effective pier length, H_eff = H – D, (m)

                       α          = adhesion factor (see Fig. 5.3)

Tension:

                        Q_t           = A_H (C_u N_u + γ’ H) + π d H_eff α C_u                                                   

            Where:

                        Q_t           = ultimate screw pile uplift capacity, (kN)

                        γ’         = effective unit weight of soil above water table or buoyant weight if below water table, (kN/m³)

                        N_u          = dimensionless uplift bearing capacity factor for cohesive soils

                       H         = embedment depth, (m)

Single Helix in Cohesionless Soil

Compression:

                        Q_c        = γ’ H A N_q + 1/2 P_s H_eff² γ’ K_s tanФ           

Where:

                         K_s           =   coefficient of lateral earth pressure in compression loading

                        Ф         = the soil angle of internal friction, degree

                        N_q          = dimensionless bearing capacity factor for cohesionless soils

                        P_s            = the perimeter of the screw pile shaft, (m)

The bearing capacity factor N_q , can be calculated using:

            N_q        = e^πtanФ tan² (45^o+ Ф/2)       OR

Table 5.1: Nq for cohesionless soils

Tension:

For Single Helix Screw Piles Installed in Shallow Condition H/D < (H/D)_cr

            Q_{t           =} γ’ H A_H F_q                                                                                                   

For Single Helix Screw Piles Installed in Deep Condition H/D > (H/D)_cr

                Q_t        = γ’ H A_H F_q^* + 1/2 P_s H_eff² γ’ K_u tanФ                                 

Where:

            K_u          = dimensionless coefficient of lateral earth pressure in uplift for sands

            F_q           = breakout factor for shallow condition, ( Fig. 5.4)

            F_q^*       = breakout factor for deep condition, ( Fig. 5.5)

Due to variations in the soil composition the exact mechanics and load capacity for any given soil condition can only be verified through actual load testing at each site. Above reflects guidelines only for the design of pier installation.

 Coefficients

Shaft adhesion is based on the effective shaft length.   The adhesion develops along the steel shaft as the pier reaches a sufficient installation depth. When the pier is used for shallow installation, and therefore doesn’t reach a sufficient depth, the adhesion factor is considered insignificant.

                                    Figure 5.3 Adhesion Factor²

K_s/ K_o varies based upon the density of the soil. The K_s/ K_o ratio is 0.75 – 1.25 with K_o determined in the following manner: 

Table 5.2: ¹

K_u is dependent on the angle of soil friction and can be estimated as:

Table 5.3:

Breakout factors for shallow and deep pier installation:

Emprical Torque Installation Method

EMPRICAL TORQUE INSTALLATION METHOD TO PREDICT CAPACITY ¹

An empirical method has been derived and used in the screw anchor industry for many years. Installation torque is used to calculate the ultimate capacity of the anchor. The average torque achieved during the last three (3) to five (5) feet of installation is directly proportional to the ultimate axial capacity of the pier.

A pullout test to failure is performed with the capacity achieved recorded as the ultimate capacity. Using the ultimate capacity at the given installation torque, an empirical torque factor can be calculated. (NOTE: A tension test is often performed instead of a compression test because they are quicker to set up and perform and the capacities are generally less than the compression tests – inherent factor of safety).

From the pullout test, an empirical torque factor, K_t can be calculated using the following:

            K_t = Q_t / T                                                                                        

Where:

            T         = Average Installation Torque (Ft. Lbs.)

            Q_t        = Ultimate Pier Capacity (Lbs.) from load test

            K_t        = Empirical Torque Factor (1/ft.)

Typical values for K_t range from 20 to 2, with the majority of soils giving a K_t value of 7 to 10. Unless load tests are performed to provide a K_t value, a conservative K_t value should be selected when designing piles. It is important to note that the value for K_t is a combination of soil and anchor properties, primarily relating to friction during installation. As an example, K_t for dense, dry sand would normally be less than for a hard, wet clay.

The factor for 2-7/8” pipe anchors is recommended to be around 7 and is usually in the 7 to 10 range for most soils. PierLogic requires all installers to use a K value of 7 for pier installation.

Appropriate safety factors should then be applied (minimum S.F. = 1.5 – 2.0).

Pier Specifications

Best Helical pile installer in Denver.  Executive Structural Piering LLC is an authorized installer and dealer of Pile Power LLC – helical piles.  Known as Denver’s best helical pile and helical pier company for the last 20 years.  Accepted by all City and County governments.  Pile Power piles and piers are designed, tested and installed to meet current IBC 2012 code requirements.  Used and approved by local soil engineer’s and structural engineer’s for residential and commercial applications.  Pile Power piles and piers can be installed by both machine and hand installation.  The available starter and extension sizes range from 3 foot to 10 foot in length.  Standard pipe diameter is 2 7/8″ with a working load of 35,000 pounds.  These piles can also be used in tension where needed.  These helical pile can be used for foundation repairs and new construction projects. Contact us for additional engineering information.

Pile Power LLC is a manufacturing company dedicated to the highest quality production of helical piles and helical piers. A leading edge company in design, testing, and construction for deep foundation systems. Pile Power LLC is located in Arvada Colorado and was established in 2012. Testing and fabrication occurs at it 6000 sqft manufacturing plant.

Engineering Pier Design

Engineering for helical piers Denver

Engineering designs for  Pile Design:

Design Installation limitations:

Piers should not be installed closer than 3 diameters of the helix apart, at any time. Piers installed in clusters, where load requirements exceed individual pier capacities, should be battered not greater than 5 degrees, in order to achieve the minimum 3 diameters apart.

Piers designed to be used in tension – use 70% of installed compression capacity.

For piers subjected to uplift (for frost depth) the embedment depth of the helix shall be at least five (5) helix diameters or deeper than the maximum frost penetration depth is in the area. Minimum pier depth is not to be less than 5’.

Pier Installation:

Installation of Pile Power LLC Piers should be completed by qualified installers only. Ultimate pier failure could occur if a proper installation criterion is not followed.

Installation of helical piers is to be completed using a torque head. Torque head should be well maintained and serviced on a regular basis. Information from the manufacture should be available to determine motor and gear efficiencies. Pressure gauges should be testing and or replaced on a regular basis. Gauge tolerances must be accurate with 1%.

Torque will be continuously monitored and recorded throughout the installation of each pier. Each pier section shall be recorded reflecting pier section length and any additional notes regarding installation conditions. Pier location and identification shall be documented as piers are installed. Such information should include; project name and location, date, weather conditions, torque head used, a site map reflecting pier placement, starting psi and finishing psi and any notes regarding installation conditions.

For small shaft piers, there is a direct relationship between installation torque and pier capacity. Continuous monitoring or torque during installation will provide the installer with a profile of the underlying soil conditions.

Piers installed, for the purpose of compression, should be installed based on the hydraulic pressure curve of the torque head. During and ideal installation, the torque values should be constantly increasing, indicating that the pier is being inserted into more dense soil. If a drop in torque is recorded, it is most likely that a soft layer (such as soft clay) was found. The pier must continue to be inserted past the soft layer until a more dense soil (i.e. higher torque) is found.

Refusal will be determined by no vertical movement of pier depth. Auguring of pier may be required in order to penetrate very hard layers of clay stone. Vertical drop, even of only 1/8” per rotation, shall continue for either a depth into hard clay stones of 2’ min or until refusal.

An empirical method has been derived and used in the screw anchor industry for many years. Installation torque is used to calculate the ultimate capacity of the screw anchor. The average torque achieved during the last three (3) to five (5) feet of installation is directly proportional to the ultimate axial capacity of the pier.

Colorado State University conducted a three-year study (1995-98) on the migration of water along helical piers shafts. The result indicates no more water penetration along the shafts of helical screw piles than along the sides of drilled concreted shafts.

The starter section of the piers is cut to a 45 degree angle in order to assist the installer in targeting the pier during installation.

Water Problems

DONT GET RIPPED OFF!!  You should understand how to stop the water from getting into your basement before you spend thousands of dollars on some system that you really do not need.  As everyone know the Denver Area has experienced higher than normal rain fall.  As a result of this many basement are flooding causing both water damage and structural issues. 

What kind of water problem do I have? 

There are two different types of water problems.   Surface water and ground water. 

How do I know if I have a surface water problem?

If you are experiencing water coming into your basement right after a heavy rain or snow melt you have a surface water issue.

How do I know I have a ground water problem?

If water is entering your basement a day after rain or when no rain has occurred you have a ground water issue.

What can I do  to fix a ground water problem?

There is really only one way to fix ground water problems.  You will need to install some type of perimeter drain system around your foundation. 

Here is an example of a typical interior drain system.

Here is an example of an exterior drain system.

When dealing with ground water either with an interior or exterior drain system the average homeowner should expect to pay anywhere from $ 8,000 to $ 15,000.  The cost is based on the total linear feet installed and other access issues.  Installing a drain system will remove the water that has entered around your foundation and discharge it before it raises to the same elevation of the concrete slab. 

SURFACE WATER REPAIRS

As I stated earlier about 90% of surface water issues can be fixed without having to spend thousands of dollars.  The better approach to surface water is to keep it away from your foundation to begin with.  With the expanding soil conditions in the metro area keeping the soil from getting additional water will help minimize foundation damage.  Here is how to solve your surface water problems.

1.  Gutters

It is critical to make sure your gutter are working correctly.  Keep them clean.  Make sure they are attached correctly and draining in the proper direction (toward the downspouts).

2.  Downspouts

Downspouts need to be attached and extended AT LEAST 5′ from your foundation.  Many times the downspouts are draining right next to your foundation.  Water will flow to the easiest path of resistance.  Since your foundation was over excavated, on average 3′ larger than the foundation itself, the soil around the foundation is less dense and compacted than the undisturbed soils that were not excavated.  Water will flow around your foundation much easier than the natural soil.  That is why the downspouts need to be extended the entire 5′.

3.  Grade

Simply put the grade around your foundation is the direction of slope the dirt is around your foundation.  If the dirt is sloping TOWARD your foundation than it is considered negative.  If the dirt is sloping AWAY from your foundation it is considered positive.  As you can guess the grade should be positive away from your foundation.  With a positive slope the water will not have the opportunity to drain down next to your foundation and will not be able to enter your basement or crawlspace.  Positive drainage will also help minimize the expansive soil damage that can occur to your foundation.

If your grade is flat around your foundation you can either raise the grade next to your house and install a barrier between your foundation and the dirt.  You can also create a swell to direct water away.

Most of this grading work can be done by the homeowner.  You can also have a landscaper complete the grading if you need too. 

Please feel free to contact Executive Structural Piering LLC if you need any additional information or recommendations.

Foundation Movement

What is foundation movement?

Simply put foundation damage is caused by soil movement. The three directions that the foundation can move is: up, down, or inward from exterior soil pressure pushing against your concrete foundation wall. Your foundation can experience all three types of movement- at the same time. The potential movement of your foundation depends upon the soil conditions around your home. These soil conditions range from not expansive to very expansive depending upon where your live. The average potential for soil expansion is around four inches, by can be as high as twelve inches in some areas. This amount of movement can severely damage your foundation and home. It is very important to maintain the integrity of your foundation.

What causes foundation movement?

Shrinking and swelling of expansive soils.  Over 90% of all foundation failures can be linked to either improper design or soil related problems. When looking to build a new home, or trying to find out what your current foundation is sitting on, it is worth hiring a soil geologist. During the wetter month of the year, soil will become soaked and begin to swell. The amount of swelling is determined by the expansiveness of the clays and underlying soils. The amount of swelling can vary from nothing to in excess of 12″. During the drier months, soil will lose its moisture and begin to shrink. The amount of shrinkage depends on how much moisture is evaporated from the soil. The more the shrinkage the greater the foundation is likely to settle. Building on expansive clay, compressible or improperly compacted fill soils, or improper maintenance around foundations also causes foundation settlement and movement. Whatever the cause, settlement can destroy the value of structures and will render them unsafe.

Moisture due to poor site drainage & building on non-compacted fill. 

Since water or excessive moisture can cause foundation movement or damage, it is very important to keep water away. Moisture can be diverted completely away from your foundation by maintaining or improving the desired elevation (slope away from) the foundation. Sufficient site drainage is extremely important in order to extend and maintain the life of your foundation structure. Water proofing, installation of drainage systems (sump pits and pumps), and French drains are all important factors in maintaining proper stability of your foundation. Building on improperly compacted soils can also affect the amount of foundation movement your home has. This normally occurs when a developer or contractor raises the elevation of the construction site above the undisturbed natural soils. The elevation difference must be taken into account when the design of the foundation is considered. The amount of fill varies upon the desired elevation of the new home of the existing site conditions. When this happens the weight of your home will begin to sink into the soil and allow the foundation to shift and create costly damage to the structure of your home.

Plumbing Leaks

During the initial construction stage of a home, quality piping and fixtures must be used. Plumbing drain lines must be constructed of dense, durable nonabsorbent materials and must have smooth, impervious surfaces, free from unnecessary concealed fouling surfaces. Older homes typically installed either clay drain pipes of cast iron drain pipes. Newer homes typically install either ABS or PVC drain lines. Installation of waste or sewer lines must maintain a slope of at least 1/8″ drop per foot toward the main sewer line in the street. Shifting or improperly installed water and sewer line can leak and add unwanted moisture around your foundation. Water supply lines are normally constructed out of copper. Older homes may still have either lead or galvanized lines coming from the street going into your home. Whether the plumbing leaks are in the water lines or sewer lines, foundation movements will inevitable occur.

How to detect foundation troubles inside the home

• Cracks in the masonry
• Gaps between bricks, doors and windows
• Bricks leaning away from garage doors
• Gaps between fireplace and house
• Sagging roof line
• Deterioration of building materials
• Structural damage supporting building materials
• Water stains around foundation
• Dirt lower around foundation (negative slope)
• Sinking exterior walls
• Separation around concrete walks and driveway
• Garage door opening sagging
• Uneven window headers and sills

How to detect foundation troubles outside the home.

• Cracks in the masonry
• Gaps between bricks, doors and windows
• Bricks leaning away from garage doors
• Gaps between fireplace and house
• Sagging roof line
• Deterioration of building materials
• Structural damage supporting building materials
• Water stains around foundation
• Dirt lower around foundation (negative slope)
• Sinking exterior walls
• Separation around concrete walks and driveway
• Garage door opening sagging
• Uneven window headers and sills

Foundation Movement Solutions

There are only a few types of foundations currently being built in the Denver area for residential homes: 1.) Concrete foundation walls on footings, 2.) Concrete grade beams either on caissons or piers. Cinder block walls are also used on occasion.

Basic Repairs

These four systems are for sinking and heaving or where the walls are pushing inward. Regardless which system you will chose for the repair of your home, there are several installation conditions in common. In order to repair you foundation the installer must get underneath your existing foundation wall. Some type of bracketing must be placed under your existing foundation in order to lift or stabilize the walls. Excavation from either the outside or inside must be completed in order to install the brackets. All piering systems must be able to support the load or capacity of the structure. Every home always has two types of load or force pushing downward on the soil. These loads are called “Dead Load” and “Live Load”. Dead load is the amount of weight that is always there – (the walls, roof, floor, furniture). Live load is an ever changing condition. Examples of live load are – (3 feet of snow on the roof, ice, wind, 30 people over for a party).

Concrete Push Piers

The concrete piers are installed in one feet section and are installed directly under the existing foundation. The first section sometimes has a cable embedded in it. A hydraulic cylinder is placed on top of the starter section and pushes against the bottom of your existing foundation in order to push it into the dirt. The starter section is open and allows the dirt to go around and in the middle of the pier. Envision the action of a cookie cutter going through dough. Because the pier edges are hard it cuts through the dirt and is pushed downward. As each section is pushed into the ground the next section is placed on top and pushed down. Sections are added until your home lifts (called refusal) or 2000 psi of hydraulic pressure is applied. The capacity of the pier is determined by the friction along the sides of the sections, as they are installed, and either 2” or 3” of end bearing. In most cases the thickness of the steel push piers are ¼” and for concrete piers 1/2” to 3/4” thick. The concrete piers are then filled with grout and used to support your home. Problems with Concrete Push Piers Unfortunately since dirt is pushed up in the middle of the pier sections during installation the mortar does not get into the starter section and many times does not get below 2’ or 3’ from the surface of the dirt. Each section is not mechanically connected and has the potential to wonder and not be in a direct line under your foundation. Failure can occur if the sections are not stacked straight. Even systems that have cable or expanding bell bottoms can not insure the pier is straight. The average depth these concrete piers are installed is 6 to 10 feet. The top 10 feet of soil is considered to be the most expansive by soil engineers. The installation of these piers do not penetrate into the bedrock. The capacity of the piers are determined by the friction of the side walls of each section and the end bearing of the pier ( 5 or 6 inches). The average loading capacity of the piers are 20,000 pounds. In expansive soils, the entire pier will lift with the soil and not protect your home against heaving. The depth of bedrock varies from area to area. The average depth for bedrock is 12 to 18 feet.

Steel Push Piers

Steel push piers are installed along side of the foundation much like helical piers. Each section is normally 2’ long. A steel bracket is bolted to your existing foundation and a hydraulic cylinder pushes the pier section into the dirt. As with the concrete piers the starter section is open and cuts through the dirt. The steel piers are pushed into the ground until your house lifts (refusal) or 2000 psi is reached. To hold the sections together during installation a smaller inner pipe, about 6” long, is tack welded to the extension section and stack on top of each other. Envision Lego’s that stack on top of each other. These sections are not bolted or mechanically connected. The capacity of the pier is determined by the end bearing of the starter section and the friction created along the shaft during installation. Most push piers have a maximum capacity or load of 20,000 pounds.

Problems with Steel Push Piers

The depth of the push piers is totally dependant upon how much your house weights and the condition of your foundation. A broken or weak foundation wall will not have the integrity required when hydraulic forces are applied. Older homes with foundation made of brick or rock do not have the strength to hold together during the installation of the piers. Most houses are not heavy enough and will lift (refusal) before the push pier reaches bedrock. During most installation, no live load is present at your home. Because push piers depend upon the weight of your house for installation there is no safety factor for increased loads. When 2’ of snow or 20 people are present this live load causes the pier to “creep” or pushes the pier farther into to dirt. This is one of the main reasons push piers are failing. Since the capacity of the pier is develop along the shaft friction, expansive soils all ready stuck to the pier, allow the pier to heave upward as the soil does causing your foundation to heave upward.

Concrete Caissons

Concrete caisson are an improvement of the pile. Original piles were first constructed of wood trees dig and placed into the ground and were used over 5000 years ago to support structures and to keep them above water lines. Modern building materials (concrete) now replace wood. They are primarily used for new construction. A drilling rig drills an 8” to 20” hole into the dirt. Concrete and steel rebar is then poured into hole and the foundation is put on top. It is important that water not be allow into the hole during the pouring of the concrete. The caisson must also be embedded into bedrock at least 5’. The capacity of the caisson is developed by the end bearing and side friction generated during installation.

What is Compaction Grouting?

Compaction Grouting is a form of mud-jacking that was first developed by J. W. Poulter in 1933. A slurry solution of filling materials is forced underneath the existing foundation wall, footing or slab. Depending upon the company, the slurry solution can be composed of dirt, gypsum, or a concrete mix. Concrete slurry mix being the best option. A minimum 1000 psi mix is recommended.

How Does Compaction Grouting Work?

The slurry is forced under pressure underneath the structure, either slab or footings, to fill the any voids. It is possible to lift the structure using compaction grouting but the injection point needs to be right under the structure to have any impact. The closer the injection point to the structure the less impact the soil compaction will have on any long term repair. As the slurry dries, unless non-shrink grout is used, it will shrink and allow the structure to sink with it. The dirt underneath the footing is compressed and strengthened. This dirt compaction only impacts the area where the slurry can apply force against the soil. Compaction grouting can not be used under foundations with grade beams. When the foundations are on concrete caissons the void must always be maintained under the foundation wall. If the void is filled with the compaction slurry it will heave the walls upward as the soil expands underneath it causing damage to your foundation.

Tie-Backs

Tie back systems are used when your foundation wall is pushing inward.  The pressure of the soil pushing against the foundation wall is greater than the concrete and steel wall can retain or hold back.  A structural repair must be made in order to stop the foundation wall from moving inward any more.  Some tie back systems can pull the wall back plumb but excavation of the entire wall must be done.  A void must be present for the wall to move back into place.  Most foundation wall should be pulled back if they are greater than 5 degrees or 3 inches out of plumb.  There are many different tie back systems now being installed. Some systems are better than others. It is important for the homeowner to understand how each system is installed and how they work.

First you must understanding what is actually pushing your foundation wall in.  The Active Zone of Soil is the force that is pushing your wall inward.

Now that you know what dirt is pushing your wall in, lets figure out how much force the tie back system needs to hold back.  The amount of weight or force can be figured out by having some basic information.  You can use the weight chart below to figure out what type of soil you may have around your foundation. 

Now measure the height of your foundation wall.  The average height is around 8 feet. 

Use the Foundation Height and Weight load chart to figure out how much weight is pushing against your foundation wall 1 foot wide for the entire height of your foundation wall.

 After selecting the pounds per square foot multiply that number by the height

If your foundation has failed you more than likely have some expansive soil around your foundation. 

Once you know why your foundation wall is pushing inward, it is easier to understand why most tie-back system’s fail.  Most homeowner want a permanent foundation repair.  Having to come back and tighten nuts is not a complete foundation repair.  If your basement is finished removing drywall every time is not a very good option. 

Reaction Plate System

The Reaction Plate System consists of a threaded rod normally ¾” to 1” in diameter. It is drilled through the wall from the inside and attaches normally to a 16” x 16” plate where a hole was dug out in the yard. The rod and plates both inside and outside are attached and the rod is tightened to “hold” the wall from moving inward. Failure occurs for several reasons.  The most common reason  is the reaction plate is normally installed in the Active Zone of Soil.  Current property boundary lines  limit the distance the plate can be installed in most cases.  The plate size also has a very limited size or contact to the foundation wall and only retains a small portion of the overall foundation wall.  The outside plate is also susceptible to the freeze thaw cycle.   Since the top 10 feet of soil is the most expansive the entire reaction plate system moves with the soil and is not very stable. 

Expanding Wedge System

The Expanding Wedge System consists of a threaded rod and a plate that is hinged much like the “molly” wall anchors used in drywall.  The rod is installed from the inside by using a hammer drill.  Each section is connected by a coupler as it is installed.  The pounding force of the hammer drill drives the rod and hinge plate into the soil.  Once the rod no longer goes in any more you have reached refusal, average length is about 6 – 10 feet, and the installation is stopped.  A hydraulic jack is then applied to “pull” the rod back out in an effort to have the hinge plate expand out causing resistance against the soil. You can measure the amount of hydraulic force used to pull the rod out to help determine the holding force.  This system fails for several reasons.  In soil conditions that are very hard the wedge plate does not expand out to hold any tension or when it does it is in looser soil and in the Active Zone of Soil.  The amount of holding or tension each wedge can hold is very limited and many wedge anchors are required to be installed.  There is no way to determine how far the hinge plate has expanded and since you have already started pulling the rod back out the soil is disturbed around the plate providing less holding force.  The amount of wall contact is very limited and only retains a small portion of the foundation wall.

Wall Brace System 

The Wall Brace System consists of a 3″ steel lightweight “I” beam that is attached to a single floor joist and bolted to the existing concrete floor.  The beam can be tightened with an adjustable bolt.  The holding capability of a single wood floor joists is very limited.  Using 2 – 3/4″ bolts drilled through the floor joist has the hold strength of 1280 pounds before a failure will occur.  Either the joist itself will split and break or the sub floor above the floor joist will fail.  The bottom of the beam is bolted into the existing concrete slab.  Most slabs are only 3 or 4″ thick and do not have any steel reinforcement the slab is not capable of withstanding additional forces.  Since each beam is only able to hold a small force before failure the spacing between each beam is very important.  If your foundation wall has already failed the soil condition around your foundation is more than likely at least moderate in it’s expansive capabilities.  For soil conditions like that spacing can not be greater than 30″ apart in order not to fail. 

Helical Pier Systems

The Helical Pier System consists of a 3″ diameter pipe helical pier and a steel strong back and is installed in sections from 3 to 10 feet in length.  The strong back is normally a 6 or 8 inch steel channel that is bolted to the foundation wall.  Installation normally occurs from the basement, where a 12″ hole must be cut into the concrete and the pier is installed by a hydraulically driven torque head.  The torque head spins and screws the pier deep into the undisturbed soil and bedrock.  The pier is installed at a angle normally around 10 to 20 degrees to insure the it is installed out of the Active Zone of Soil.  The torque or force is measured during installation so that holding or tension forces can be determined.  The steel strong back runs the height of the entire wall so that the holding force is spread equally into the foundation wall.  The average length of installation 14 – 20 feet. Spacing of the strong backs depends upon the height of the foundation wall.  Average spacing is 7 to 8 feet apart.  Failures are extremely rare since the helical is anchored into undisturbed soils and the amount of force is measured and is calculated to meet the structural needs of the foundation wall.

Counter Fort Systems

The Counter Fort Systems are mostly constructed with concrete.  A 8 inch thick wall is poured and attached to the existing foundation wall.  The new foundation wall normally extends perpendicular 3 to 4 feet out from your existing foundation in the shape of a “T”.  The end of the counter fort in held into place by a helical pier or footing.  The counter fort system does not allow the wall to be pulled back plumb.  At Executive Structural Piering we have a unique patent pending system that uses steel instead of concrete and can be installed in less than 1 day and well below the cost of a concrete counter fort.  Engineered to the highest standards and design this system can be installed on any foundation wall.

Epoxy

The basic way to understand Epoxy Injection is that it does the same for concrete as welding does for steel. Usually when a foundation fails, large cracks form and remain in the walls or grade beams even after foundation underpinning. These cracks can be weak points in the foundation wall and can allow moisture to creep into the living area. We can repair the crack by injecting a high strength epoxy resin under high pressure into a cracked area and seal it. Studies have shown that once the resin dries, the foundation will be stronger at that point and should not crack in the same place again.

Soil Types

Soil Types The easiest way to group soils is into two categories: cohesive and non-cohesive. Fine- grained soils such as clay are considered cohesive. Sand and other coarse-grained soils are non-cohesive. The classification of cohesive and non-cohesive soils may be further sub-divided based on origin, method of deposition and structure. Soil structure may be classified as deposited or residual. Deposited soils have been transported from their place of formation to an anchor location. Residual soils are formed by physical and/or chemical forces breaking down parent rocks or soils to a more finely divided structure. Residual soils are often referred to as weathered. Soil structure properties can be divided into loose, dense, honeycombed, flocculated, dispersed or composite. Often these soils are in layers of different thickness of unlike soils, These soils do not necessarily retain consistency of materials at various depths. Trouble free anchoring demands the careful evaluation of local soil conditions and anchor types. Without proper soil/anchor planning, maximum anchor performance an never be assured. Almost all of the soil types classified below can be found in the Denver area.

Shallow and deep foundation anchors A couple of soil failure may occur depending on the depth of the helix; shallow and deep. Foundations expected or proven to exhibit a specific mode are usually referenced as shallow or deep foundations. Which basically points out the location of the surface and a sudden drop in load resistance to almost zero. With deep foundations, the soil fails sequentially, maintaining significant post-ultimate load resistance , and exhibits little or no surface deformation. The dividing line between shallow and deep foundations has been reported by a number of investigators to be three to eight times the foundation diameter . The five-diameter depth is the vertical distance from the surface to the top of the helix. The five-diameter rule is often simplified to 5 feet minimum. Anytime a foundation anchor is considered, a deep foundation should be exercised. Deep foundations have two key advantages over shallow foundations. (1) it provides an increased ultimate capacity, (2) failure will be incremental with no sudden decreases in load resistance after the ultimate capacity has been obtained.

Soil Groupings Throughout the Denver area there are a wide variety of soil conditions present. Some areas consist of very sandy conditions that will not support even load designs of 1000 pounds per square foot. While no more than 2 miles away the soils are so expansive that additional design requirements are needed.

Soil test probe

Foundations have long been dependent upon excavation, penetration and lab tests of core samples. When construction is concentrated in an area, this is still desirable, but for an overhead line or underground pipeline, which may extend for hundreds of miles, economic feasibility requires a less costly yet dependable determination of soil properties. The portable soil test probe provides a new dimension. This instrument, portable and operable by one man, will provide reproducible numerical data related to resistance of the soil to flow under load . It may be used in soils up the uniformity of hardpan , to any depth below the surface and without the need to make an excavation or otherwise disturb the soil. A probe consists of a head on a square shaft with a number of extensions, all of which may be coupled together. A ratchet wrench with a torque-measuring handle is used to install, remove or take readings. Corner marks at 1-foot intervals provide means to determines the depth below the surface when a reading is taken. The hub of the probe head is forced into the ground by application of torque acting on the blade of the probe. Thus the torque required to turn the probe is proportional to the resistance of the soil to penetration of the hub. When determining end bearing foundation work , the bearing strength of the soil can be calculated directly from the probe reading. Most heavy-duty probes can withstand torque to 1800 (units?). That basically means that the probe will not penetrate packed gravel, shale or rock.

Below depth (ft) probe (ft) description

13 0 0-100 top soil

10 5 150-175 Gray clay

13 10 150-175 Gray clay some red clay

13-15 175-225 Gray clay, traces of sand

20 20 225-300 gray clay with sand, light rock-wet

Bearing capacity theory

This theory suggests that the capacity of a foundation anchor is equal to the sum of the capacities of individual helixes. The helix capacity is determined by calculating the unit bearing capacity of the soil and applying it to the individual helix areas . Friction along the central shaft is not used in determining ultimate capacity. Friction or adhesion on extension shafts may be included if the shaft is rounded and at least 2.5” in diameter.

Water, Frost and Soil The typical minimum foundation depth required by code is three feet. This measurement is taken from the top of the soil to the bottom of the footing. The depth is important so that freezing of the ground will not lift the footing and foundation. If an anchor helix is in a zone of deep frost penetration (cold winter seasons), frozen soil will behave as a stiffer soil and will basically yield greater holding capacity, by hard soil with brittle cracking instead of softer depressible soil. However, when spring begins to thaw out the soil, the overlying zone will be water-saturated while the layer housing the helix remains frozen. The condition is comparable to a hard layer under a soft layer, and may result in sudden anchor failure. Occasionally anchor jacking or movement out of the ground occurs during these conditions. When dealing with permafrost, the helix should be at least three to five feet below the permafrost line; provisions made to prevent solar energy from being conducted down the anchor. Anchor holding capacity decreases as moisture content increases. If a helix is installed at the water table level, anchor capacity can reduce helix capacity by as much as 50 percent in granular soil. Water, draining from fine grain soil under load, will permit creep, slow movement of the ground under a steady load. This is similar to the consolidation marvel under a foundation. Rapidly applied loads due to wind or ground tremors have little effect on creep so long as they do not exceed soils shear water slowly drain off. Under such circumstances, creep could become troublesome even though the anchor/ soil system has not structurally failed.

Helical Piers

Helical piers where first develop around 1833 in England by Alexander Mitchell. They were originally used to support the foundation of lighthouses in Tidal Basins. Around the turn of the century helical piers gained interest and were mostly used in the Utility Power, and Petroleum Gas Industries. They were used to support and secure oil pumping rigs, power transmission towers and foundations for buildings.  A helical pier is constructed from steel and is produced in either round pipe or square shaft depending upon the manufacturer. Round pipe piers are seven times stiffer than square shaft piers and provide additional stiffness allowing for greater lifting support. If too much force is applied to the square shaft piers during installation, the steel will twist or yield causing the steel to change and become more brittle. This limits the depth the pier can embed itself into bedrock. The first piece installed is called the starter section. The starter section has a helix welded to the bottom of it. The standard diameter of the helix is eight inches. Installation of the pier is completed by the use of a torque head. The torque head is powered by hydraulic pressure and applies twisting force which drives or screws the pier into bedrock. Twisting force is measured in foot/pounds. After the starter section of the pier is screwed into the ground an extension section is then mechanically bolted to the starter section. By adding additional extension sections the length of the pier is unlimited and will reach bedrock regardless of the depth of that bedrock. To determine the capacity, or holding strength, of the pier the foot/pound of force used to install the pier is measured. The average torque used to install the pier is between 3,500 and 8,000 foot/pounds of force. The average capacity or load for helical piers is between 20,000 and 60,000 pounds.

The amount of force required to screw the pier into the bedrock has a direct correlation to the capacity of the pier. Through proven engineered mathematical equations, empirical data, and extensive field testing it can be determined what load the pier actually has. Because the pier is installed using a torque head, and not the house itself, the piers can be installed with a safety factor of as much as 5 or 6 times the actual load that the house needs. Any additional live load that is applied after the installation of the piers will not cause the pier the fail. The weight from your home is supported on the eight inch helix of the pier. Because the weight is concentrated on the helix, expansive soil is pushed around the pier and does not lift the pier as the soil moves upward. The average depth helical piers are installed is between 12 and 20 feet.