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  • Writer's pictureKevin Peterson

HOW MUCH DOES IT COST TO FIX A FAILING FOUNDATION?

Updated: Apr 25


KEY TAKEAWAYS

  • Slope in floors exceeding 1 inch per every 20 feet are signs you may have a big problem

  • Costs to repair minor to major problems can be between $10K’s to $100K’s

  • Seismic retrofitting can be a great way to prevent future issues



In the San Francisco Bay Area, it is very difficult to provide an average cost for a foundation repair simply because there are so many variables. 

  • Slab or raised foundation (Majority in the SF Bay Area are raised)

  • Brick foundations are inferior to modern foundations as they tend to shift, crack, and crumble in our earthquake prone region.

  • Height of foundation

  • Ease of access

  • Is there room for heavy equipment? Is there an area to dump the excavated soil and the debris from the old foundation?

  • Method of repair recommended by the structural engineer or inspection agency. 

  • Extent of damage

  • The total length (i.e. linear footage) of the perimeter foundation along with any interior foundation or isolated footings impact the cost.

  • Basement involved?

  • Buildings with basements cost more because basement walls are a lot bigger than a spread footing and require more work to remove, to replace, and to install the correct drainage.

  • Soil issues

  • Expansive soils contain a lot of clay which swells when it gets wet and then shrinks by that same amount when it dries out.

  • Large trees around home that have “slurped” up all the moisture and dried out / shrunk the soil.

  • Inadequately compacted backfill soil before construction.

  • Erosion of soil caused by poor drainage around home.

  • Soil creep – Soil creep is a phenomenon where soil at the top of a hill gradually makes its way down the hill. Soil creep can cause lateral movement in homes built on hillsides.

  • Poor construction

  • Renovations like adding a story to a house 

  • Landscaping and concrete that may need to be removed and replaced


In this article, we’ll attempt to answer the following questions...

  1. What are common signs of foundation issues or what can become an issue?

  2. What Is the severity of slant on a floor before it becomes an issue? 

  3. What are minor to medium repairs and how much do they cost?

  4. What are major repairs and how much do they cost?

  5. What if you have brick foundations?


Let's dive in...


SIGNS OF FOUNDATION ISSUES

  • Moisture in the crawl space

  • Torn wallpaper – There might be a cracked wall behind the torn wallpaper. You might even see drywall cracks or nail pops.

  • Sticking windows and doors – Maybe they jam or don’t open or close all the way, etc. If it’s just one window or door, it’s probably not a foundation problem. However, if multiple windows and/or doors behave strangely, it’s likely a foundation issue.

  • Sloped or sagging floors – Even slightly uneven floors can signify foundation trouble.

  • Ceilings and/or floors that have separated from the wall – The separation doesn’t have to be large to signify structural damage.

  • Cracked floors – Look for cracks that go across the floor, wall to wall. Cracks limited to one or two tiles were probably caused by something falling on them.

  • Wall rotation – This happens when the soil outside your home’s foundation gets oversaturated with water that can’t drain off. Eventually, the outside foundation wall starts to sink into the soil while the inside part of the wall lifts because it’s on drier ground. This will cause the wall to rotate.

  • Moldings detached from the ceiling and/or floor – Even small detachments can signify foundation trouble.

  • Stair step cracks in brickwork – This is a sure sign of foundation problems.

  • Chimneys and/or porches separating from the house – The problem might be related to the foundation under the chimney or porch. However, there’s a possibility your home’s foundation has a problem.

Cost to fix foundation


HOW MUCH SLOPE IN THE FLOOR IS UNSAFE? 

There are two tolerance levels for single family homes when it comes to diagnosing if a foundation is in need of repair based on the degree of slope in the floor.

  1. The most stringent standard permits a total maximum differential of 1.5 inches before the house is considered out of level.

  2. The second standard originates from the Uniform Building Code suggesting a maximum deflection of 1/240. This calculates to a maximum of 1 inch per every 20 feet.


A site specific soils report from a Soils Engineer oftentimes determines what the expected degree of settlement would be based on the soils and the foundation design/type and it may be greater, or less than, the 1 inch in 20 ft.


WHERE IN THE SF BAY AREA DO FOUNDATION ISSUES OCCUR THE MOST?

Soils rich in clay and silt have the greatest potential to damage a foundation. Expansive clay soil can cause foundations to crack, heave and shift. When clay soils dry out, they shrink and crack, leaving gaps around the house, allowing water from the next storm to penetrate easily and repeat the expansion cycle. Clay-rich soils typically cause more foundation damage by expanding than by contracting. One example of this type of soil here in the SF Bay Area is Alluvial soils. These soils are for the most part soft in nature due to high water content.

Here is a map provided by the United States Geological Survey (USGS) showing the different types of soil we have here in the SF Bay Area.


Soil conditions of SF Bay Area - Cost to fix foundation




MINOR TO MEDIUM REPAIR COSTS

FOUNDATION CRACKS (1/8 inch to 1 inch)

These cracks generally occur from a combination of shallow foundation embedment depth and expansive soils which will swell when wet and contract when dry, foundation settlement, or past seismic activity.


Foundation wall cracks - Cost to fix foundation


Foundation wall repair costs:

Option 1: Cover the crack surface with epoxy and monitor ($140-260 per crack) Can 

  • Can be done by a homeowner or handyman. 

  • This is not considered a structural repair but will allow for monitoring.


Option 2: Fill the crack (epoxy or mortar) + add a steel plate ($700-1,300 per crack) 

  • Performed by a qualified & experienced contractor).

  • This will span the crack and anchor into the foundation.


EFFLORESCENCE

Efflorescence is an indication of excessive moisture that appears when water that contains soluble salts evaporates from the surface of the foundation or soil, resulting in a crystalline salt deposit. The deposits are usually white but they can also be green, brown, or gray depending on the mineral composition. It is not a severe condition in and of itself but can be an indication of inadequate site drainage. 


Signs of efflorescence - Cost to fix foundation


Or, if the area has a high water table, the full surface of a crawl space could be damp. The full background and hydrogeology of an area can be ascertained through a soils report and further research. Note that it is not uncommon in some areas of the Bay Area to have high water tables.

 

Efflorescence repair costs:

Option 1: Sump pump ($2,100-$3,300 for pump & pit install) 


Option 2: Install of vapor barrier ($3,000-$12,000)

  • Keeps the humidity levels down and reduces chances for rot and mold. A low cost vapor

  • Simple barrier might be a few thousand dollars. A robust system with welded seams and a thick membrane might be in the $12K


Option 3: Drainage away from foundation ($1,000-15,000)


Drainage away from foundation - Cost to fix foundation


Note: when planning crawl space improvements, any foundation work should be completed before the installation of the vapor barrier. Otherwise, additional costs will be required in order to patch or repair portions of the vapor barrier following

the foundation work.


PIER AND BEAM

Interior footers on a raised foundation are typically attached to the floor beams using a concrete pier and a wood post. The common approach to remediating issues is to make them wider and deeper to improve their performance and/or install adjustable posts to allow for future adjustments as needed.


Pier and post - Cost to fix foundation


Pier and beam repair costs:

On average, new piers and beam run approximately $2,500-$4,000 per interior post install.


CRIPPLE WALLS

Cripple walls are short walls, typically constructed of wood, found between the foundation of a building and the main floor. These walls provide support for the floor joists and the structure above. Cripple walls are commonly used in buildings with raised foundations, such as those in earthquake-prone areas, to elevate the structure above potential floodwaters or to allow for ventilation and access to utilities. They are often vulnerable to damage during seismic events if not properly reinforced, hence they are a focus of retrofitting efforts to improve a building's resilience to earthquakes.


Cripple walls - Cost to fix foundation

Cripple wall seismic retrofit costs:

Option 1: The average range for seismic retrofits is between $5,000 and $10,000, with most homeowners paying $7,000 for cripple wall bracing and foundation bolting in a 2,000 sq. ft. home. This project's low cost is $1,000 to brace a cripple wall in a 1,200 sq. The high cost is $20,000 to retrofit a 3,000 sq.ft. home with a soft story and shear wall reinforcement.


Cost to fix foundation for earthquake retrofit


MAJOR REPAIR COSTS

Spalling


Spalling is the chemical breakdown of concrete within the concrete mix itself (rock, sand, cement). Typical causes of spalling concrete include but are not limited to: excessive moisture and/or poor site drainage conditions, poor quality cement used in the concrete mix, incorrect ratio of cement to the amount of water, sand and/or rock in the concrete mix, and excess salt-mineral residue in the sand used in the concrete mix.


Spalling of concrete - Cost to fix foundation

How to determine the severity of spalling? Most inspections will use a probe and strike various areas to investigate the extent. If the foundation crumbled in areas when probed then further testing may be needed such as destructive testing like core samples or extensive rebound hammer testing for a full analysis.


There is no good repair options where the foundation is spalling short of foundation replacement. Minor issues when probing will show damage is primarily on the surface with solid concrete remaining beyond so monitoring periodically, and

Improving the flow of water away from the foundation are two key action steps to take when noticing the start of spalling.



Replacing an entire foundation can be cost prohibitive but raising a sinking foundation is possible using three different methods of underpinning - hydraulic push piers, helical piers, and concrete piers. Underpinning entails tapping into more stable soil or rock deep in the earth through push piles, helical anchors, drilled piers or similar deep underpinning technologies, as well as brackets or grade beams which anchor the foundation to the piles effectively supporting it on more stable ground.



PIERS - HYDRAULIC AND HELICAL

Raising a sinking foundation using hydraulic push piers involves first attaching steel brackets to your foundation. A hydraulic ram then attaches to the brackets and drives heavy duty steel push piers deep into the soil until they reach load-bearing strata. Once the push piers are in place, hydraulic jacks are placed on top of them, and the building is raised. The jacks are then removed, but the piers remain permanently in place.


Helical piers (also referred to as screw piles or helical piles) are another method used to lift up sinking foundations. They’re shaped like screws and are turned into the soil until they reach load-bearing strata. Hydraulic jacks are then attached in order to lift the building back up.


Here’s an example of the hydraulic push piers in action (courtesy of Bay Area Underpinning)


Hydraulic pier costs:

On average in the SF Bay Area, using “hydraulic piering” will cost between $18,500 – $58,000, using the following Foundation Repair Cost Breakdown:

  • $800-$3,500 to hire a structural engineer

  • $1100-$7,000 for soil reports from a geotechnical engineer

  • $630-$1600 for a building permit with street parking

  • $6,000-$14,000 for seismic work (if you live in an earthquake area)

  • $2,000-$5,500 for hidden obstacles (tree roots, old repairs, deep footings)

  • $3,000-$4,000 per pier (repairs for an average size home require 12 to 18 piers)



PIERS - DRILLED CONCRETE 

There are different types of foundation settlement. Structures built on hillsides have soil that washes downhill, causing foundation settlement and lateral movement. Slab piers are custom-designed foundation repair tools that provide a permanent solution for sinking slab foundations. 


A drill rig is used to drill large diameter holes – typically 18” in diameter and from 15-30 feet deep – next to the foundation. Reinforcement cages are then placed in the holes and concrete is poured in to create the cast-in-place drilled concrete pier.


Drilled concrete pier costs:

Cost is based on a variety of factors including the depth, diameter, and number of piers needed. Also, whether or not a standard drill rig can access the area. If not, a portable drill rig is needed and that will increase the cost.


BRICK FOUNDATIONS


Concrete Capping

This process is exactly what the name suggests. Rather than replacing a brick foundation, concrete is poured over un-reinforced masonry (brick foundation) and bolting the layers together. This is not recommended, as forces from earthquakes would still act on deteriorated brick.



Seismic Retrofitting

This process involves modifying the existing foundation to make it more resistant to ground shaking and soil failure normally caused by earthquakes. It includes expanding the existing foundation with concrete or adding materials like steel braces, bolts, or shear walls to a foundation to increase its capacity under a home. These types of improvements can start at $50K.



Replacement

Replacing a foundation is the most costly process, as it entails removing the brick foundation entirely and replacing it with reinforced concrete (reinforced, meaning there is rebar inside the concrete). It can happen in either sections or be done holistically. Its costs can start at $150–200K.



If you are considering purchasing a home with a brick foundation, it’s important to:

  1. Hire a structural engineer to assess the structural integrity of the building and understand the integrity and any work needed to strength it.

  2. Get a BIG discount (compared to a concrete foundation listing).



Hopefully you found this article helpful regarding the costs to fix a foundation. Please share with anyone you feel could benefit from this information. If you’d like to discuss further your home or home search here in the SF Bay Area or beyond, happy to help. Please reach out to me at 650.451.8763.



Additional Resources Regarding Cost To Fix Foundations:






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