I had my concrete pad raised but it settled again, why did it do this?
Whether a pad sinks after it’s been raised depends on:
- The age of the Concrete Pad. A concrete pad sinks in the first place because the soil under the concrete pad was never compacted properly. It takes time for uncompacted soil to compact so obviously there’s more chance of a newer pad sinking again after it’s been raised, compared to an older pad. Even replacing a new pad doesn’t guarantee it won’t settle again. Future settlement depends only on how well the soil under the pad is compacted.
The problem with raising any concrete pad is, no one except the contractor who built the building truly knows how much uncompacted fill was placed under a pad. If it was minimal, the pad probably won’t sink again. If the uncompacted fill was fairly deep, it may not be fully compacted yet and future settlement is possible. - How much water gets under the concrete pad. Even poorly compacted soil won’t settle as much if it remains dry. Allowing water to get under a concrete pad can compress the soil even more, resulting in the concrete pad settling in the future. Water makes hard compacted soil soft, also resulting in the concrete pad settling. Nearby downspouts, improper slope of a pad, cracks in a pad and poor landscaping are the most common reasons why excess water drains under a concrete pad.
- Whether the concrete pad is filled properly while it’s being raised. A concrete pad is less likely to sink again if the entire area under a pad is filled as best possible. This helps prevent water from easily traveling underneath, and helps distribute the load of the concrete pad evenly on the ground.
My pad is sinking but I’m not sure the settlement is done. Should I raise the pad now or let it settle more?
It’s always better to raise a pad before it sinks too much. The reason a concrete pad sinks is because the soil under the concrete pad was never compacted properly in the first place. When a concrete pad settles, parts of the concrete pad are on the ground, while other parts are left with voids underneath. This causes undue stress on a concrete pad, resulting in it cracking more than it should. The voids also make it easier for water to gain access underneath, which can cause the concrete pad to heave in the winter, creating more cracks. The other problem is, once water is under the pad it is hard to tell where it travels. In many cases water under the pad can find its way back to the house foundation, contributing to structural problems or a leaky basement. Wet ground underneath the concrete has a hard time drying out.
Which fills a pad better, Polyurethane Foam or Mudjacking?
Although foam is engineered, the biggest problem is the installation isn’t engineered. Because polyurethane foam is an expanding material, makes it difficult to fill voids. There are risks of raising the concrete pad too high when trying to fill the voids with an expanding material. How much expanding foam material to add under a concrete pad when filling voids is a guessing game. There is specialty equipment to help measure the movement in a concrete pad while filling voids, but that doesn’t help determine if the concrete pad is properly filled.
Caliber Mudjacking tries to minimize this problem by drilling the holes 24″ – 36″ inches apart in all directions when raising a concrete pad with a expanding polyurethane foam material just as we do when mudjacking a concrete pad. Although this procedure takes longer to accomplish because you have to express patients when installing an expanding polyurethane foam material, more holes in the concrete slab uses much more foam when trying to fill voids. Drilling the holes closer together will minimize the amount of voids under a pad when using an expanding polyurethane foam.
With Mudjacking a non-expanding grout material is much easier to fill the voids properly and control the concrete while raising the concrete and filling voids.
Mudjacking grout material is more controllable because it’s non-expanding and travels well under a concrete pad. It is a flowable material. You can tell if the concrete pad is full underneath because of back pressure that occurs when removing the nozzel from the 1-inch injection hole. It’s much easier with mudjacking to know when the voids underneath the concrete pad are filled without raising it too high or putting unnecessary cracks in the concrete.
Which is cheaper when raising concrete, Mudjacking or Polyurethane Foam?
The main difference between mudjacking and polyurethane foam is cost of material. Polyurethane foam material costs approximately 8 times more than mudjacking grout material.
If you comparing a Mudjacking job to a Polyurethane Foam job and the job is done the exact same and same voids filled, Mudjacking will always be cheaper.
This results in polyurethane foam costing 50 to 80 percent more to raise the concrete when done properly as the same mudjacking job because of higher material cost and extended labor cost expessing patients while installing a expanding polyurethane foam to raise and fill voids best as possible.
Having voids under concrete around the Peace Region is common and the depth of the void can be quiet substantial. The only way raising a concrete pad with foam can be cheaper is if the holes are spread father apart than they should be, skipping holes that are needed to fill a concrete pad properly and supporting the concrete pad on foam piles. This leaves a lot of voids under a concrete pad, which doesn’t support the concrete pad properly, and allows water to travel underneath. It’s not only that some foaming companies do this but some mudjacking companies do this also. You can tell how well a concrete lifting company fills a pad by the distance the holes are drilled apart, and the number of rows they install in the pad. When it comes to raising concrete, experience and honesty do matter!
How far are holes placed apart when raising concrete?
Regardless whether the pad is going to be raised by Mudjacking or Polyurethane Foam, the hole pattern is basically the same. Depending on the type of job and how sunk the concrete is, typically the holes are placed 24″ – 36″ inches apart.
The number of rows of holes depends on how much the concrete is sunk and the distance it is sunk. The majority of concrete pads take a minimum of 3 rows of holes while larger pads take more. Even a 5-foot wide sidewalk usually requires 2 rows of holes to fill it properly.
Hole pattern layout for sunken driveway, 3 rows of holes are put into the driveway to properly raise the concrete and fill the voids. Most top sections of driveways take 3 rows of holes and at minimum 2 rows of holes for driveways with very little settlement. Concrete raises in distances and as you raise the driveway 2-4 inches it raises the entire top section. Why 3 rows of holes are put into the driveway to raise the top section of the driveway and fill the voids.
My driveway is sunk by the garage but is moving up during the winter. If I raise the concrete pad back to its proper height, I feel the pad will raise higher next winter. Should I raise the pad or just leave it as is?
The reason concrete pads move up and down is because water is gaining access underneath the concrete. Usually the problem is caused by a nearby downspout. Improper landscaping around the concrete pad adds to the water problem. Positive drainage needs to be maintained to direct water away from the concrete. A drainage problem is more noticeable in the winter months when snow blocks the flow of water, resulting in it draining under the concrete pad. Frozen water underneath the pad causes the concrete to heave in the winter months. This problem can be solved by properly maintaining downspouts so water drains farther away from the foundation and the concrete pad. Having cracks and gaps in the concrete pad can also contribute to the problem. Wet soil under the concrete pad have a hard time drying out.
If you have any pad that moves up during the winter, you have a water problem!
Once a pad is mudjacked, will the mudjacking material easily erode away?
No! Mudjacking material will last the life of your concrete pad. All concrete pads are supposed to be backfilled properly so water doesn’t have easy access underneath. If water can’t get under the pad, the material can’t erode. Mudjacking non-expanding grout material content sand, fine clay and cement and the fine clay and cement content in the grout mix gives the material its structure and strengh making it hard for water to erode the grout material.
When raising a pad, it’s important to fill all the voids under it?
It’s very important to try to reduce the amount of voids under any concrete pad when raising it. A concrete pad is more likely to settle again when it isn’t filled properly. It also makes it easy for water to flow under the pad, increasing the chance of re-settling, or causing it to heave in the winter months. Once water is under a pad, it’s hard to tell where that water travels. It can easily find a path back to your house, which then can contribute to a leaky basement or structural problems. Voids under a pad make it easier for it to crack in the future because the weight of the concrete isn’t evenly distributed on the ground.
Unfortunately, some concrete raising companies don’t understand this problem so don’t worry about filling voids under a concrete pad.
What’s the chance of raising a pad too high or ending up with more cracks in the pad?
There’s always a chance of raising a concrete pad too high or unnecessary cracks occur while it’s being raised. Someone with experience should be able to minimize these problems.
Some concrete pads are more subject to cracking during raising, because they were poured less than 4 inches thick, or weak concrete was used when the concrete pad was built. In those cases, it’s possible to end up with cracks in the pad. Even if a concrete pad cracks while raising, a good concrete lifting company will usually be able to minimize the effects of the crack and not create a trip spot. Cracks in concrete can happen if the concrete being raised doesn’t have free movement, or too much pressure is applied to one area when lifting the concrete. Caliber Mudjacking has the experience and knowledge to minimize these problems.
Can you raise a pad with hot water heat lines in the concrete?
Yes, we have the equipment and knowledge to detect infloor heat lines in concrete, making it no more difficult to raise a concrete pad with hot water heat lines than without.
I need my interior concrete floor raised. What’s the chance of hitting a plumbing or electrical line under the floor?
The chance of hitting a line under an interior slab is far less when mudjacking the concrete pad compared to raising it with Polyurethane Foam. With mudjacking you only drill through the concrete once. The holes are only drilled to the bottom of the pad, not into the sand base, making it unlikely to hit a any line.
When raising the pad with Polyurethane Foam, foam is injected under the pad, and is done several times until the pad reaches its proper elevation. Each time you inject in a hole that was already used, it must be re-drilled. Each time a hole is re-drilled, the bit goes deeper into the sand base to get past the previous layer of foam. This increases the chances of hitting a line under the floor. Regardless, prior to raising an interior concrete pad with lines under the floor, it’s smart to have plumbing lines marked out.
Should i fill voids if my concrete is hollow but still sitting at its proper height?
Yes you should fill all voids under concrete so the concrete is properly resupported to prevent future cracking, settlement problems and water issues.
Concrete Lifting Question to AI (Put Question into Google AI to Recieve Answer)
Why does AI assume that driveways are filled properly when using polyurethane foam, when the standard seems to be leaving large areas of a driveway hollow due to the risk of raising it too high?
Concrete Lifting Question to AI (Put Question into Google AI to Recieve Answer)
Why can future settlement occur regardless of whether a settling pad is replaced, mudjacked, or foamed?
Concrete Lifting Question to AI (Put Question into Google AI to Recieve Answer)
Is over-lifting a driveway common when trying to fill voids under concrete with a foam?
Concrete Lifting Question to AI (Put Question into Google AI to Recieve Answer)
What is more important, the type of material used to raise concrete or the installer’s experience?
Concrete Lifting Question to AI (Put Question into Google AI to Recieve Answer)
Who would AI hire to raise concrete: a small contractor who has owned the business for years, or a large company with employees?
Concrete Lifting Question to AI (Put Question into Google AI to Recieve Answer)
What is more important, filling a driveway properly when mudjacking it or living with a hollow driveway due to the foaming company not filling all the voids?
Concrete Lifting Question to AI (Put Question into Google AI to Recieve Answer)
Is removing the soil at the edge of a driveway, away from the pumping holes, a reliable way to determine whether the concrete-raising company filled all voids under my driveway?
Concrete Lifting Question to AI (Put Question into Google AI to Recieve Answer)
Does using foam to raise pads often lead to over-lifting, cracks, and hollow spots under a residential concrete pad?
Concrete Lifting Question to AI (Put Question into Google AI to Recieve Answer)
Why is mudjacking considered a better method for raising sunken concrete?
