Jacking Up My Concrete Driveway - Advice Sought

[toxcrusadr]

I live in a 1989 walkout ranch (driveway and garage on the upper level) built on clay soil. Soil around here is notorious for shrinking over the years. My driveway has been settling and there is now a 2-3" step up into the garage where the two slabs meet. Neither one is cracked (much) and the garage and house seem OK more or less. I'm thinking of getting some estimates for mud jacking the driveway so it's level with the garage slab again.

I see there are these polymer foam products they say are lighter and faster and cheaper. I just wonder about the longevity of foam under there. I would not be surprised to find after another 10 years that the foam degraded and the slab sank again. Then you get some concrete guys and they say they can't inject concrete with that foam in there so then you're looking at tearing out the driveway. I just don't trust its durability.

BTW the driveway has rebar going into the garage slab, and the sinking has caused pieces to spall off of the vertical face of the garage slab that you can see looking down into the crack. Should we cut that rebar before jacking? I don't want to bust the garage slab because it's in very good shape.

Any opinions or experience on the foam, or other advice on mudjacking?

 

[highvoltage_]

I would cut the rebar, it sounds like it's holding the slab to the garage. You might find that after you do cut, the slab might sink a bit further. I don't have any experience with mudjacking.

 

[sKiZo]

I just had my garage floor jacked with the polyfoam last fall. Made it through the winter all right anyway, and that's with a few thousand pounds of load. Worth noting ... it's not the typical foam used for home insulation and such. This is heavy duty closed cell specially formulated for the job, so it's pretty much permanent.

One of the stated advantages is actually the light weight. Settling is usually due to improperly compacted fill under the concrete, and a typical "mud" jacking will compress your fill even more. Also, as the foam expands, it creeps into any loose fill, helping to lock it in place. I had hollow voids under some areas that were a good six inches. I can now tap the entire floor with a pipe and it all sounds the same.

Installation took maybe three hours, so it's quick and painless. They drill a grid of half inch holes every four feet, pound in special injector nozzles (less holes, smaller holes than mud), and hit it with the foam. Minutes later, they patch the holes with expanding concrete to where they're mostly invisible. The guys what did mine even color matched the old concrete ... nice touch!

Very competitive in price, and a five year guarantee too.

** Here's a video of the exact same process used on my garage.

PS ... not to say we're not all completely honest and forthcoming with our sales pitches (cough! cough!) but ... I wonder if the reason why you hear bad comments about the foam is that they don't have the specialty equipment required to do it right? Only two companies in the state here that could do it, and their rig cost a right big chunk of change. Also, it's pretty new tech.

Oh. And the most common reason for any foam degrading is UV ... if you're getting enough sun under the slab for that to be a problem, you've got more serious problems to deal with than settling, eh. <G>

 

[jcamero]

I wonder if the poly would work if filling the void under the garage a fricken groundhog created?

 

[sKiZo]

... any void ... and I'm sure it'd also preserve said groundhog for posteriorarity as well ... <G>

Amazing how much damage those little beggars can do, and how fast they can do it, right? Imagine my surprise when I found my rider mower half buried one day with excavated dirt. I went around and plugged any other holes I found (they always put in a back door) and shoved half a dozen mole bombs into the remaining hole. Plugged that up and watched green smoke oozing from the ground for 20 feet around, and no more groundhogs ... score one for the alpha dog! Word must have got around, as it's been a couple years now, and haven't seen one since.

 

[ETLS]

I've had several friends have their driveways foamed, all were happy with the results.

And on an off-note, beneficial nematodes will eliminate the food source for burrowing animals. No food, and they go elsewhere.

 

[sKiZo]

... that would explain why both my neighbors yards are ripped up ... my groundhogs have moved on, and I didna need no nemo toads ...

PS ... I checked into them lil toad thingies a while back. It'd cost me around $500 per application and they don't reliably survive the winters here. Recommendation is for two applications per year during the prime seasons. I can buy a LOT of mole bombs for that kind of money, and the problem doesn't just move ... it disappears.

 

[toxcrusadr]

Mole bombs? I need those! Winter was pretty warm here, it's like they didn't even hibernate, just kept digging.

Thanks for the driveway advice. I found several contractors around here so I think I'll get estimates for both foam and concrete.

Cutting the rebar seems like a good idea to me too, I was going to point it out when they look at it.

I might have them do under the porch too. It's raised about a foot above the driveway and has void space under it where the soil has sunk. I have no idea why the porch hasn't dropped but probably because it's attached to the front of the house foundation. The driveway has dropped 2" at the porch step. Over the past 20 yrs I've shoved dirt under the porch (when I could get my whole arm into the space) followed by more dirt and once I even mixed up clay slurry with a paint mixer/drill and piped it in there with a garden hose. Still there is space as the clay continues to shrink. A little different situation from the driveway.

 

[sKiZo]

The smaller bombs work great for moles. My local feed and grain has giant size bombs that are more appropriate for bigger critters. I've got a piece of thin wall aluminum pipe that I'll set into the entrance and pack in tight with dirt. Drop one of the big bombs in, fuse side in, and cap the pipe with a wet towel so all the smoke goes into the tunnels. If all I've got is the small ones, I'll tape a few of those to a stick, twist the fuses together, light them, and push that into the pipe. Groundhogs especially have some pretty complex systems underground, and this stuff spreads a long ways, leaving no place to hide.

** Good idea to have a bucket of dirt handy. See any green smoke oozing out of the ground, drop a shovel full there to plug the leak. Just rake that in when you're cleaning up.

Back to foam ... My garage slab was an interesting application, as it's one piece, poured at the same time as the raised foundation walls. No place for any extra foam to expand in other words. Look at the video, and you'll see a lot of excess foam coming out around the concrete as it's injected. Took a while for them to get to me, as they wanted their top guy on the job - kind of a "foam whisperer" I guess, who could tell exactly what that stuff was doing under there, so no blowouts and the floor is perfectly flat now.

PS ... all bets are off no matter what you do if it's an uncontrolled erosion issue. No repairs will last if you've got water washing the fill from under the repair ... Mine was perfectly dry, so no problem there ... just poorly compacted before the slab was poured. Guess the big guy with the big shoes taking a couple laps with a rake wasn't enough? <G>

 

[toxcrusadr]

Definitely not erosion here, just settling. We are actually at the top of a slight incline along our street lengthwise, but front to back the lot drops a full story with slanted yards along each side of the house. So the uphill wall of the house - the front - would have been excavated 8-10 ft to get the front wall and foundation in and you can't hardly recompact that clay as well as it was originally.

 

[FONSguy]

You could plant catnip on your property, which attracts cats. They get blasted on the nip and then want to play with the chipmunks, moles etc.

 

[2526]

You could plant catnip on your property, which attracts cats. They get blasted on the nip and then want to play with the chipmunks, moles etc.

The organic approach.

 

[onwardjames]

Moles......man, I go to WAR with them bastards every year. And no, mine didn't quit digging this winter, either.

I've tried bubble gum in the holes, poison, traps, there are feral cats all over my neighborhood, but still, you'll break an ankle walking the expanse of my yard, not to mention my sidewalk has cracked in 4 spots in 10 years due to their burrowing. House also settling, drywall cracking.

Mother Nature is reclaiming what is hers, just slowly.

 

[Djcoolray]

I'd dig it all up and do it right and never, EVER have to deal with it again as consistency is always the best option. In California they have the same clay situation and create the best foundation for a proper driveway by removing soil and adding about six feet of rock, then two feet of gravel. Then put your driveway on top.....and you will never EVER have another problem. It's just getting to the point to realize that any quick fix is only going to become a history of a succession of quick fixes that ultimately inflates the cost of fixing the driveway. It doesn't cost much to dig it out and drop in rock, crushed rock then gravel....large to small, then a nice wide proper driveway that increases the value of your property. But in your situation because of the soil composition the depth of the bottom layer of rock is omni important. Because you have to take in consideration having a wet stormy winter that saturates the ground....so, it's like the concept of building a better mouse trap. Anything that deserves being done, deserves being done right.....

 

[toxcrusadr]

I hear ya. This thing is 2 cars wide and probably 30 ft. to the first joint where it begins to slope down to the street. The slab is in pretty good shape except for some hairline cracks. I don't know what it would cost to break up and remove, dig dirt, bring in rock, compact everything, and repour a slab, but it's got to be more than the jacking.