According to VIC Underpinning the base cost of underpinning services is usually priced based on linear footage. The cost, on average, to excavate two feet deep on any property is between $370 and $400 per linear foot of the property. Bench footing, which is a necessary part of the process averages between $270 and $300 per linear foot. That being said, there are frequently other questions that factor in to the total cost.
- Depth of basement (generally two feet, but an engineer should look at the distance from the top of the new slab to the finished grade)
- Height where main drain enters the home. This equates to the height of the underpinning job. The only outlier here is if a sewage ejector has been installed in the home.
The equation that you then want to look at is length and width of home, add them together and then multiply the prices listed above per foot. Here’s an example:
Your home is 20 feet wide and it is 50 feet long:
Circumference: 20 + 20 + 50 + 50 = 140 feet
Base cost: 140 feet x $385/feet = 53,900 $
Bench footing: 140 feet x $285/feet = 39,900 $
Total cost: 53,900$ +39,000 $ = 93,800 $
There are many other costs which can dictate the total cost of an underpinning job:
Dependent on where you live, you may need to use different types of materials, so that your foundation remains as solid as possible in the soil that your home is built on. These can include cinder blocks, plywood, faux rock, vinyland plywood to name a few.
As stated above, there are different materials for different types of soil and these range widely, dependent on where you live. It’s important to work with professionals who can properly analyse your soil before you execute on any sort of underpinning work.
Size of property
Yes, the general rule of thumb equation is shared above, but your home may be built on a hill or unique configuration. This can require several different underpinning jobs so that your house remains safe and comfortable.
Underpinning is a big job and you want to ensure that it’s done right. You’ll want to factor in any permitting costs, which will be specific to your area. Reach out to your local building council to ensure that you’re following all rules and regulations.