Foundation Repair With Steel Push Piers
Piering is the most cost-effective way to solve your foundation settlement problems. There are two major types of piers to lift foundations and stabilize the structure. Push/Resistance Piers and Helical Piers/Piles. There are pros and cons to both types of systems out available. On this page we will focus on Push or Resistance Piers.
Push piers uses steel piers attached to the foundation based on the engineering requirements of the structure. The steel piers (think 3-4 inch heavy duty pipe) are hydraulically driven to stable bedrock or or soil that will support the structure, and the weight of the structure is transferred to the steel brackets attached to the foundation. This pier bracket is fastened to the concrete footing and is below the ground so nothing is exposed once the process is completed. (They bury it).
As they install each pier, it is load tested with a safety factor calculated to ensure a reliable permanent solution. What this means they "should" drive until the pressure reaches high enough to support 1.5 to 2 times the weight of the structure. The structure weight is based on the normal construction practices and what structures weigh per foot that is on the footing.
They will space the piers out as wide as the pier will support, or what the concrete is engineered to span. Normal pier spacing is every 6-8 feet. If you have an estimate with them spaced further apart than this - get another estimate. Engineering would say they concrete in most construction won't support piers spaced out further than that.
Of course pier spacing will greatly affect how much the foundation repair job will cost you. But if they don't have it right - it won't work or will fail in the future. Any reputable foundation repair company should be able to show or explain the capacities of their pier products and how they figured the spacing on your job.
Once all the piers have been driven where needed, it is time to lift or stabilize the structure. They will hook up all the lifting devices to the piers and lift the building. Typical lifts are 1-2 inches, but we have seen as much as 11 inches in extreme cases.
On the majority of Missouri foundation lifting projects, windows and doors that used to stick will become functional, and cracks and other blemishes can be permanently repaired without concern for them reappearing.
There are many variations of a pier that can be used for specific applications. The only difference usually is just the bracket that is attached. Some examples are
- Below-slab vertical piers
- Porch piers
- Pre-construction piers
- Center beam piers
- Low profile piers
There is likely a price difference for specialized bracks for some applications.
Lifting Vs. Stabilize Foundations
So what's the difference between Lifting and Staiblizing my foundation? Glad you asked - because there is a difference in both what happens and how much it costs.
Lifting a foundation (really means lift and stabilize) involves more work including a complete dig out of the foundation where it is affected. They will drive the piers, hook them all together and lift the structure back to close to the original elevation. They will then pin it off so it stays there (that's the stabilize part). So on a basement they are digging down 7-9 feet deep to attach the pier brackets. On a craw space they can just dig square holes at each pier location so the excavation is a lot less (and cheaper).
Stabilizing a foundation simply means they will drive piers to that engineered pressure and depth and lock things off without lifting the structure. There could be a couple of reasons to do this. One - it might be less damaging to the structure to just stabilize. Another reason might be that the structure has been moving up and down depending on the moisture content or seasons. By the time the crew gets there your structure might be level but subject to move during the next season. So no need to lift it higher and break something.
We actually saw some customer issues with jobs like this. The estimator went and designed a plan to lift a house 4 inches. It was several weeks before the crew showed up to do the work and by then the soil had gotten a lot of rain. The house actually had reclaimed or lifted back up 2-3 inches. So the crew only lifted about 1 inch during the process. The homeowner felt cheated that the company didn't lift as much as expected and actually sued the company. They lost - but not after a lot of expert testimony where geo-technical engineers had to educate the judge and jury why this is possible.
Another gotcha some less than reputable companies have pulled in the past is selling and lift and then switching to stabilize only. What happens here usually is they bid cheaper lighter piers or change the spacing to make the bid cheaper - thereby getting awarded the bid. Once they get out there they push the piers into the ground and try to lift it. When it won't lift (because they don't have the capacity to do so) they pawn it off as they are afraid the foundation won't take the stress and it would be better to just pin it off there.
At the end of the day - pay attention to the differences and plan on being there the day the lift is suppose to happen.
Pier Depths (How Deep Will They Go?)
Most companies price piers at so much a piece with X number of feet installed per pier. The reason why they do this is because the steel pier pipe costs money and it takes so many minutes per section of pipe to install it. At some point if your piers need to go very deep - they will loose money.
Many companies have a depth pier log showing other properties in the area and how deep you are likely to go. I have seen pier jobs average 9 feet per pier and some go over 70 feet deep! Keep in mind as we talked about above - they need to go until they hit good soil or bedrock or the pier is worthless for supporting your structure.
Most foundation repair companies will do one of a few things.
- Price with 15-20 feet of pipe which is the average normal around the state PLUS so many $ per ft after that.
- Price unlimited depth but perhaps cost more per pier.
- Swtich to helical piers to keep from going as deep and saving steel and money.
This is where marketing and sales lends itself more to the process than common sense. Foundation repair is a very competitive industry and they have to make money otherwise they won't stay in business. (the ones that get this part wrong don't stay in business). So which way is better for you the customer?
My thought is I would like to only pay for what I need but I want to save money anywhere I can. If you need a lot of piers extra footage could add up more than the original estimate. It may make sense to have a soil boring done to determine how deep you are likely to go. (If you are having to finance this project it could make a huge difference also on how much to ask for at the bank).
So you may wonder - why not just go with helical piers to start with. Well for one they typically are a lot higher in cost and harder to install in tight areas. So they may not be cheaper. See our section on helical piers for pros and cons of helical piers.
Visit with the estimator about what your options are if your piers end up going very deep. (The job foreman should let you know once they have driven the first pier how deep they are going - so be sure and be available at least via phone while your job is on going.
How Much Will Foundation Repair Cost Me Using Push Piers?
Again there are many factors in the costs of foundation repairs. They are:
1) Lift vs. Stabilize
2) Depth of Piers
3) Number of Piers Needed (Spacing)
4) Size of piers (capacity)
5) Basement or Crawl Space
6) Access to the Affected Areas
7) Cost of Steel
So here is a rough estimate to help you with the sticker shock when the estimates start rolling in.
Most designs will call for piering from crack to crack where the foundation is broken. Starting with a pier ON the cracks (2) and spaced no more than 8 feet apart. So if the two cracks are 24 feet apart, you would need 4 piers. One at each crack, one at 8 feet, and one at 16 feet. The estimator should provide you with a drawing of your structure showing the placement of the piers.
Pier prices will typically average between $1000 and $2000 each installed inclluding the excavation and repairing the dirt work. So in the above example you could expect to spend $4000-$8000 for the foundation repair. Again this is a rough estimate and your mileage may vary.