Can you successfully repair foundations?

With today’s technology and trained experts, there are a number of very successful solutions to the problem of sunken concrete that involve little or no disruption to normal living or business routine. The two most common methods of this type of repair are slabjacking and hydraulic jacking (also known as piering). 


Slabjacking 


In a slabjacking operation, grout is pumped beneath a slab or beam to produce a lifting force that restores the member to its original elevation. In piering, steel posts are driven through unstable soil and hydraulic jacks are used to raise or stabilize concrete slabs affected by changes in the underlying soil. The repair method used depends on the type of distress being treated. Slabjacking is an alternative to replacing sunken or uneven concrete, restoring sunken concrete slabs to their original grade and is performed on cracked and sunken concrete slabs such as driveways, steps and sidewalks, concrete pavement floors and other slab on grade surfaces. Performed properly, slabjacking can not only bring the concrete up to grade, it can also eliminate costly and irritating water problems by filling hidden cavities under the concrete and diverting water away from the foundation.

Piling or piering

Piling or piering is the technique of driving steel pipe pilings to remedy failing building foundations and to correct foundation settlement. Push piers consist of sections of galvanized or epoxy-coated steel pipe that are driven into the soil with a hydraulic ram. Helical piers use screw piles with steel shafts. The lead section, with one or more helixes attached, provides the needed bearing capacity. The piers are screwed into the ground with a hydraulic torque motor.

With either system, one or more steel piers are driven to rock or a suitable soil bearing layer and are connected to the foundation through a metal head assembly. Once a suitable bearing stratum is reached, each pile is tested to a force greater than required to support the structure. Hydraulic jacks attach to the embedded steel piers and are used to raise the foundation back to its original elevation. Once the structure is restored to the desired elevation the piles are affixed (bolted or welded) to wall brackets, locking the new elevation of the structure.

Piers also offer an affordable solution for decks, porches, patios, hot tubs as well as pre-fab buildings. Piling or piering is the technique of driving steel pipe pilings to remedy failing building foundations and to correct foundation settlement. Push piers consist of sections of galvanized or epoxy-coated steel pipe that are driven into the soil with a hydraulic ram. Helical piers use screw piles with steel shafts. The lead section, with one or more helixes attached, provides the needed bearing capacity. The piers are screwed into the ground with a hydraulic torque motor.

What does it cost?

The average foundation repair cost is difficult to quantify because of all the variables that can affect each home or structure, according to DeWayne Snider (Yellow Hat Home Inspector and Architect). He says that the typical foundation repair using hydraulic piering runs about $10,000 to $14,000 for an average home ($1,340 per pile at 6- to 8-foot spacing). A repair of a simple crack in a poured concrete wall is usually in the range of $800 to $1,500 per crack. For slabjacking work, the typical cost of concrete removal and replacement on a porch or sidewalk is $150 per hole.

In addition to the complexity and scope of the problem, other variables that can add to the cost of foundation repairs include:

1. Hiring a structural engineer to assess the damage (typically $300 to $1,500).
2. Getting a soils report prepared by a geotechnical engineer, if needed (about $500 to $3,000).
3. Obtaining a local building permit, if required ($75 to $150).

Dealing with hidden obstacles in the ground, such as old repair methods, extra-deep footings, or tree roots may add an average of $1,000 to $2,500 to the overall cost. Although the total cost for foundation repairs can be substantial, Snider notes that your home is often your biggest investment and these repairs when properly done by a reputable contractor, can be essential to protecting your equity and keeping your property marketable.

Important tips when hiring a contractor

Foundation work is definitely not a do-it-yourself project, so it makes good sense to get at least three licensed contractors to give you a detailed proposal along with an assessment of your issues. The average inspection takes about two hours. Ron Davidson of Ram Jack Systems also offers the following advice and precautionary measures:

"Educate yourself on foundation repair methods and ask a lot of questions. Don't make your final decision based on advertising and cheap prices. If it sounds too good to be true, it probably is.

Don't do business with a contractor that does not have their foundation repair methods evaluated by ICC-ES (International Code Council Evaluation Services). This nonprofit organization ensures that building products meet code compliance.

In most areas of the country, a reputable contractor will have a clause for the depth of the hydraulic piling (typically 20 to 30 feet). Beyond that depth, there is usually an additional charge, ranging from $20 to $30 per foot. If a contractor has no depth clause, be cautious. It's unlikely that the contractor would continue to operate at a loss, and would instead just stop at the depth that would guarantee a profit.

Some foundation repair projects require removal of landscaping in the areas of the work, and the contractor typically won't guarantee that a bush or shrub will survive after removal and replacement."

Warranties or guarantees

Warranties or guarantees for foundation repair work are very important, so pay close attention to their terms. Remember that a warranty is only as good as the company that backs it. Look for a national company that can offer a warranty trust. This means that if the company goes out of business, there is a plan in place to provide follow-up service, if needed.

Protecting Texas Foundations

Foundation Maintenance Program

Soils of the North Texas area contain highly active clays which exhibit a high degree of expansion when wet and shrinkage when dry. This situation can result in severe vertical and/or lateral displacement of supported structures. Repeated variations in soil moisture content cause differential movement and undue stress to structural elements of a building, resulting in broken and unlevel floors, masonry cracking and misalignment of doors and windows. Consistent soil moisture content is key to controlling these problems. In this week's article I provide a guide to identifying problem areas and offer solutions that will help you protect your home.

Maintain Good Drainage

The illustration below shows in a graphic form how the grading should be around a home. You can see that the sloping grade directs the water to the swales which in turn channels the water away from the foundation. Ideally you should have a slope around your foundation of 6” in the first 10’. 

Avoid Water Traps

Avoid trapping water against your foundation.  Water can be trapped against the building by raised flower beds, using metal edging or other borders that do not have openings to allow water to escape, by sidewalks or other obstructions.

A common problem is poor gutter down pipe design leading to erosion and moisture build up. This illustration shows a gutter emptying next to the foundation which will cause problems over time. The solution is to add gutter down pipe extensions as shown.

However, the very way in which your home was built can cause a problem. In the photograph below, water run off from the roof is pooling in the area below and the foundations on either side are trapping it.

To remove large volumes of water you may have to install a French drain. The general construction of a French drain is shown in the following illustration.

Trees and Shrubs

If you have large trees around your house, and the trees are closer to your foundation than the height of the trees, consider installing root barriers to keep the trees from pulling water out from under the foundation. Large trees or shrubs can consume tremendous amounts of water and should not be planted next to the foundation. When planting these items, be careful that roots of mature trees do not extend beneath the foundation. Trees can cause settlement and invade your drains, all of which can lead to costly repair bills.

Avoid Low Moisture Levels

Whenever cracking of soil occurs or soil is noted to be pulling away from the foundation, it is an immediate signal that soil moisture levels are too low. Water should be added in a slow, systematic manner using an automated sprinkler system or a soaker hose placed 18 in. from the foundation with holes facing downward. Water should be applied until runoff is observed. During hot weather, this process should be repeated four to five times weekly - less during winter months. In summary, remember that a consistent moisture control program will minimize soil movements, resulting in less stress and longer service life of the structure.

Why are Texas Structures Susceptible to Damage?

Never mind how it happens just tell me how to stop it!


In Texas the types of structures most often damaged from swelling soil include foundations and walls of residential buildings, light (one- or two-story) commercial buildings and retaining walls. Lightly loaded one- or two-story buildings such as residences are especially vulnerable to damage because these structures are less able to suppress the differential heave of the swelling foundation soil than heavy, multi-story structures.

What Type of Damage Is Caused?

Damage sustained by these structures includes: distortion and cracking of pavements and on-grade floor slabs, cracks in grade beams, walls, and drilled shafts, jammed or misaligned doors and windows, and failure of steel or concrete plinths (or blocks) supporting grade beams.

The magnitude of damages to structures can be extensive. It may impair the usefulness of the structure and detract aesthetically from the environment. Maintenance and repair requirements can be expensive, and the expenses can grossly exceed the original cost of the foundation.

What are the Causes?

The leading cause of foundation heave or settlement in expansive soils is change in soil moisture, which varies due to rain fall, vegetation, irrigation and drainage. Differential heave may be caused by non-uniform changes in soil moisture, variations in thickness and composition of the expansive foundation soil, non-uniform structural loads, and the geometry of the structure.

Doming Heave

Heave of foundations, although often erratic, can occur with an upward, long-term, dome-shaped movement that develops over many years. Movement that follows a reduction of natural evapotranspiration is commonly associated with a doming pattern of greatest heave toward the center of the structure. Evapotranspiration refers to the evaporation of moisture from the ground surface and transpiration of moisture from heavy vegetation into the atmosphere. 

The pattern of heave generally causes the external walls in the superstructure to lean outward, resulting in horizontal, vertical, and diagonal fractures with larger cracks near the top. The roof tends to restrain the rotation from vertical differential movements leading to additional horizontal fractures near the roofline at the top of the wall. Semiarid, hot, and dry climates and deep water tables can be more conducive to severe and progressive foundation soil heaves if water becomes available.

Cyclic Heave

A cyclic expansion-contraction related to drainage and the frequency and amount of
rainfall and evapotranspiration may be superimposed on long-term heave near the perimeter of the structure. Localized heaving may occur near water leaks or ponded areas. Down warping from soil shrinkage may develop beneath the perimeter during hot, dry periods or from the desiccating influence of trees and vegetation located adjacent to the structure. These edge effects may extend inward as much as eight to ten feet. They become less significant on well-drained land. Heavy rain periods may cause pending adjacent to the structure with edge lift and reversal of the down warping.

Edge Heave

Damaging edge or dish-shaped heaving of portions of the perimeter may be observed relatively soon after construction, particularly in semi-arid climates on construction sites with pre-construction vegetation and lack of topographic relief. The removal of vegetation leads to an increase in soil moisture, while the absence of topographic relief leads to ponding. A dish-shaped pattern can also occur beneath foundations because of consolidation, drying out of surface soil from heat sources, or sometimes lowering of the water table. Changes in the water table level in uniform soils beneath uniformly loaded structures may not contribute to differential heave. However, structures on a deep foundation, such as drilled shafts with a slab-on-grade, can be adversely affected by a changing water table or changes in soil moisture if the slab is not isolated from the perimeter grade beams and if internal walls and equipment are not designed to accommodate the slab movement.

Do You Have Cracks in Your Walls? 

Have you been told they are cosmetic and can be patched up? Sometimes, covering up or ignoring cracks can lead to very costly problems. Soils in the north Texas area contain highly active clays which exhibit a high degree of expansion when wet and shrinkage when dry. 

In Texas, homeowners have long been concerned with movement in their foundations and the subsequent cracks that can appear in walls around doors and windows caused by differential movement. When you find a crack what should you do? The answer is to monitor it over time to see if it opens or closes indicating movement. To do this effectively, you need to set up crack gauges to measure movement of structural cracks in concrete, brick and masonry.

The monitoring process is carried out over a number of weeks (or months) and allows the movement of the home to be measured. The cost of the monitoring survey is $580 and includes the installation of two crack gauges. The gauges are then read at 4 and 8 weeks. Additional readings can be taken over shorter or longer periods at a cost of $125 per visit. At the completion of the monitoring period you will receive a report detailing the findings. If you have cracks in your walls, act now. Costs for major foundation repair can be astronomical! It's always less costly to fix problems when they are small

  

It's going to freeze again!

When cold weather hits, emergency calls to plumbers skyrocket. Why? Many homeowners neglect simple plumbing protection until it's too late. Do all you can to prevent frozen or burst pipes by keeping these guidelines in mind:

1. Plan ahead! Don't wait until the last minute to protect your plumbing--by then, it might be too late. Take steps to protect your pipes as soon as colder weather is in the forecast, at least several days in advance.
2. Protect pipes where they enter your home. Close your foundation vents, and use simple insulation to prevent cold air from coming in. Don't forget to open the vents back up in the spring!
3. Detach all hoses and outside lines. It might seem like a simple thing, but many homeowners forget this vital step. Drain your water hoses and put them away in winter storage. Turn off or disconnect pipes to outdoor water sources, such as that water garden in the backyard.
4. Close off your outside faucets. Most homes have a separate valve for the outside faucets. Turn the valve off, then go outside and run all the water out of the faucets.
5. Can't drain outside faucets? Protect them! Molded foam covers are a great help, as well as fiberglass and plastic insulators. For a quick fix, even newspapers and old rags molded around the faucets and held in place with plastic and duct tape works.
6. Drain your sprinklers. Many homeowners forget about the sprinkler system, and that can lead to a plumbing nightmare. Check with the manufacturer to learn how to turn the system off.
7. Insulate pipes in unheated areas. Pipes in your basement, attic, crawlspace, and even exterior walls are vulnerable to the elements. Insulate them with molded pipe sleeves or insulating tape.
8. Open lower cabinet doors. It might not be the most attractive look, but keeping your cabinet doors open during the coldest weather allows more warm air to circulate around the pipes.
9. Run the water. When the temperature takes a serious dip, run a bit of cold water out of the tap. A steady drip or small stream of water helps keep the lines open and prevent freezing.
10. Make vacation plans for pipes. When you are leaving your home for several days, turn your water system off. Turn off the main valve and run every faucet until the pipes are drained. Don't forget to do this with your washer, too!