How much polyurethane does it take to lift concrete slabs in sidewalks and driveways?
We’re often asked “how much polyurethane does it take to lift concrete?” We can estimate how much it will take to get your concrete lifted back to its original position, but we have to take a few things into consideration.
When is it necessary to lift concrete?
Our polyurethane foam is a two-part expanding chemical combination that, when combined, creates a chemical reaction that generates heat and expands into a foam, strong enough to lift and hold concrete slabs. Our polyurethane mixture can be used to fill voids under concrete slabs where the ground has settled. If your concrete is sinking into a void, we can inject this material into it to lift the slab until your concrete is level again.
How we estimate the amount of polyurethane it takes to level your concrete
In order to estimate how much polyurethane it will take to lift and level your concrete slab, we actually find out how many cubic yards of dirt is missing, underground, which our material will be replacing. So, if it is a 10′ x 10′ concrete slab in your driveway and it has settled on two sides 1 inch it will take .23 cubic yards of material to get the slab lifted.
The difference between Mud Jacking and Polyurethane concrete lifting
In our industry, there are 2 main competitors, Mud jacking and our polyurethane lifting services. Mud jacking contractors charge by the cubic yard of material they inject into a void and polyurethane contractors charge per pound of material which is converted from cubic yards. The reason for this is that polyurethane foam is purchased by the pound in liquid form.
How we know the size of underground voids
A question often asked at the time of the estimate is “how do you know how big the void is under the slab?” We look for signs of voids the best we can by looking at the side of the slab to see if we can see gaps and we also check to see if it sounds hollow under the concrete; that is good indication of a void. It can be hard to tell how deep the void goes though, so instead of guessing we like to drill a very small hole in the joint (where it will be inconspicuous, even when we patch it) and putting a stick down to measure the distance to the dirt. This is the most fool-proof way to find out how much foam compound it will take to fill the void.
Why polyurethane foam is a better solution to your underground void
After answering “how much polyurethane does it take to lift concrete” the next question is usually “why not remove and replace the concrete?” Some of the advantages of having your void filled with polyurethane foam rather than removing and replacing the slab are that we can save lots of time and money. The price of concrete lifting seems expensive at the time but when you think about the alternative it is half the cost or less, of the alternatives. When you remove your concrete to fill a void, you will have to:
- Spend a full day of removing concrete and hauling it off to a place that accepts concrete, which usually comes with a price tag of its own.
- The next step is to compact the dirt in the bottom of the void and bring more dirt in, to get it back to the proper grade so that a new slab can be placed.
- The concrete contractor has to set forms for the new concrete and a big concrete mixer has to come and place the concrete.
- The contractor has to finish the concrete then come back a day or two later and strip the forms.
- You’ll then need some landscape restoration performed where they had to set their forms.
- You’ll have to wait to drive on the concrete for a week, and it won’t match any of the concrete around it.
The bottom line is that you are typically down for about a week at least, the cost is astronomical, and there is a much better way to resolve your problem. Concrete lifting, concrete leveling, and void filling can come in handy in these instances.
So, to answer your question, “how much polyurethane does it take to lift concrete” it varies; but it takes less material than the alternatives and it costs less. Our jobs typically take about 2 hours, and you can drive on your concrete again immediately after the work is complete.