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What is Underpinning and How Much Does It Cost?

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  • Underpinning

Underpinning is the process of reinforcing and stabilising the foundation of an existing building. It is the construction of added support to strengthen a structure or footing. Underpinning supports the foundation of a property where the structure of it has changed due to moisture and other causes. Underpinning can also be done if the soil is not suitable for building construction.

The cost of underpinning varies depending on several factors. On average, the rate of foundation underpinning ranges from $5,000 to $35,000 for small and simple projects. In cases of major foundation repairs, underpinning services are about $40,000 to $80,000. Underpinning services can be costly, but they are necessary for structural integrity and overall safety.

When Do You Need Underpinning?

Underpinning is necessary when subsidence is actively occurring. Subsidence is the slow and steady sinking of the ground caused by human activities or natural processes. If not addressed promptly and adequately, it may pose a danger to people and property. It can also result in a drastic decline in property value.

Here are some indicative signs to check if your property needs underpinning.

#1. Misaligned Doors and Windows – Doors and windows out of alignment are an indicator of foundation problems. Doors and windows may lean and pull away from the frames, or there are wide gaps around them.

#2. Cracks on Walls and Floors – Minor hairline cracks are expected; however, more significant cracks mean bigger foundation problems. Observe the cracks for a few months and see if they are widening. If they are, you may need to contact a free underpinning assessment service.

#3. Floor is not Level – Unlevel floors are a tell-tale sign of foundation issues. Also, look for uneven trenches in the building or slab's edge.

If there are worries after your initial assessment, it is always best to seek the advice of an underpinning specialist.

What are the Other Causes of a Foundation Failure?

#1. Drainage causes excess moisture that can lead to soil erosion and consolidation.

#2. Dry tree roots can also dry the soil under your property, causing it to shrink, thus damaging the foundations.

#3. Leaking pipes can cause soil erosion.

#4. Extreme heat conditions can lead to soil shrinking and can move your house foundations above it.

#5. Inadequately prepared soil compaction beneath your home may cause foundation damage.

Typical Cost for a Home Underpinning Work

The cost for underpinning typically depends on the extent of the damage. Below is a table with an estimate of how much is the cost for a home underpinning work across Australia - from repairing a simple crack to extensive foundation damage:
Unfortunately, most home insurance does not cover underpinning works citing home wear and tear as a homeowner's responsibility. Still, it won't hurt to ask if they allow financing as your payment option.

Factors Affecting Underpinning Cost

Computing the total cost for an underpinning project involves different factors. Some major factors affecting underpinning cost are the following.

#1. Extent of Damage

Assessment of the problem's extent needs to be done before you can identify the cost for underpinning. The degree of foundation damage is the number one contributor to the total project price. The bigger the problem is, the more extensive workforce, time, and materials needed to complete the project.

#2. Cause of the Problem

The leading cause of foundation damage and other contributing factors generally affects the amount of time and equipment to use during underpinning. For instance, if tree roots cause it, you need specific equipment and machinery to do it. Same with the type of soil, water infiltration damage, or settlement problems.

#3. The Foundation Method

The building foundation impacts the underpinning solution and methods to be used. Depending on the damage assessment, a contractor may use any of these three underpinning methods: Slab Jacking, Piering, or Grout/Resin Injection. Each method has differing costs.

#4. Foundation Accessibility

Access issues are factors affecting the cost of an underpinning service. When foundation accessibility is limited, there are restrictions to the underpinning method, increasing the amount of time to complete the job. In some cases, special apparatus may be used to repair the damage.

#5. Underpinning Expertise

Embarking on an underpinning project involves several expert opinions for it to be efficiently and successfully completed. In most cases, a trade professional is involved and the expert advice and report of structural engineers, geotechnical engineers, and underpinning professionals.

It is essential to find experts and professionals to work with. You need to find a trusted Structural Restoration Service with qualified, reliable, and experienced tradespeople to get the most of your money.

How to Save on Underpinning Cost?

Underpinning is expensive and understandably so. However, there are some smart ways to avoid overcharges and unexpected increases in cost.

Typically, an underpinning service includes engineering fees and other miscellaneous costs. Still, there are some instances wherein you may incur extra costs. To avoid overcharges, you can ask your contractor to work on a fixed schedule. Discuss with your contractor how you want to proceed with the project and be transparent on your allotted cost and expectations.

Agree on a fixed time frame and total cost, ask for clarification and explain any concerns you may have regarding the project. The price for an underpinning service should be fixed and must include all the necessary expenses from soil tests, engineering reports, site inspections, and all the work and materials needed.

Contact at least 2 to 3 underpinning companies and ask for a free assessment, necessary information, and price quotation so that you can compare prices and services.

Do I Need a Structural Engineer?

An expert assessment by a structural engineer is needed for any underpinning project. Aside from giving professional advice, an engineer's report is also necessary for you to get the required permit to proceed. Most structural restoration contractors have a structural engineer as part of their underpinning service package, so there's no need for you to get a separate assessment. You can directly contact a contractor, and they are the ones to prepare everything for you.

Are There Other Alternatives?

Underpinning can be a costly and time-consuming process. If your home requires underpinning and you and your family are not yet ready, you may consider resin injections instead. Resin injection can compact loose soil and raise a structure to a standard level. It is also faster compared with other underpinning methods. Nonetheless, a structural engineer's design and conditions are still required.

Will Underpinning Provide a Permanent Fix?

Depending on the soil where your property is in, as well as the type of underpinning method you choose, determine if your foundation problems can be permanently fixed or not. Experts in foundation underpinning give honest suggestions on what type of method is the best for your property.

Can I Underpin a House Myself?

Even if you work in the construction industry or have underpinning knowledge, it is best to let professional builders do the task. Underpinning is a complex process, and although resources and DIY instructions are readily available on the internet, doing it yourself can sabotage your home structure's integrity.

We highly suggest working with a trusted building and underpinning specialist with years of experience to guarantee proven systems and quality work. If you are in Adelaide and within the South Australia area, we at Structural Restoration Services Pty Ltd can help you.

What Does Underpinning Entail?

Underpinning is a long process that would usually take about 4 weeks, depending on the damage. After the assessment, reports, and other preparation, your builder will either use machinery or manually dig holes beneath the existing foundation and fill it with concrete. They will then work on replacing and reinforcing existing structures as may be necessary.

Do I Need to Move Out While Underpinning is Ongoing?

In most cases, underpinning repairs and the general work involved is not disruptive. However, it can be messy.

Talk to your builders about how they would like to proceed. Some builders may suggest that you temporarily vacate your property while the work is ongoing. That way, you can plan and make reservations ahead of time.

Final Thoughts

Underpinning your property to ensure safety and building integrity is costly but is definitely worth it. One smart way to cut costs is to work only with an expert and trusted name in the structural restoration services.

Structural Restoration Services Pty Ltd  has more than 35 years of experience in working with South Australian homes. We understand your need to treat your home with love, care, and respect. We provide the best industry practice and workmanship and offer the best value and service in South Australia.

You can visit us at 24 Kitawah St., Lonsdale, South Australia, for free site assessments and quotes, or you can call (08) 8326 4477.

You may also check our website to get to know more about us and our services.

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Related Blog Content:
What to Do if Your Floors Aren’t Level
Top 5 Reasons Why You Need Residential Underpinning
Guide to Understanding How Underpinning Can Help You