That's on the excavator who didn't compact the foundation dig. I've seen it many times, they just dump loads and loads of backfill without compacting and then do a little at the end on top. Really need to backfill in separate lifts compacted with water.

That is impressive how the concrete stayed suspended. Proves the need for rebar.

Old rebar is obviously laying on the stone, not up in the concrete. That's a mistake often made by careless contractors. Glad you used some chairs to support the new rebar. In 42 years of commercial construction I never saw one of those fun tools you used to push the stone back under the existing floor. Seems to work pretty well as long as there are no voids further back than you can reach. I would have used a vibrator around the edges to get the new crete back under the old floor.

Nice work!

Nice job Tom!👍🏻👍🏻

I think the title should be... how important compacting is lol and using the sorrento type of fill! To me and in my area the sub base is the most Important reinforcement u can have, then rebar or wire then fiber

great job. nice when your work shines thru.

Whats up guys? Just got this vid, good stuff. Ppl think fiber is a primary reinforcement and it's not its a 2nd dary reinforcement! Can't wait for the new season

Great job Tom you really know your concrete

You have a great bunch of guys

Wow. That proved all you say about rebar and the quality of your work. I hope the ground under the house footings are solid or that would be a big disaster. So good to see a pro in action. I like the finish, looks like aggregate. Good job Tom and another good video! Thanks. 👍👌❤

Nice work :)

Good compaction is very important to him

Very nice job.

Gut wrenching when you showed the gap. Great video.

Well done 🤜🤛😎

Surprised they did not have you replace all of it. There has to be some gaps closer to the door that you could not see. Great work by your Crew Tom.

@Bigmikkey55

2 жыл бұрын

Couldn't agree more . The homeowner is really getting screwed here.

@JohnSmith-tv5ep

2 жыл бұрын

@@Bigmikkey55 by the builder ? Doubt That!! I would think that GC worked out something with the homeowner and Tom was doing the repair as per the General Contractor. Homeowner happy with the fix? Don't know! but if the front cracks, and sinks you can bet fingers will be pointing 👉 👈 to someone but it won't be Tom's crew!

Well done guys, good forever fix

great and informative video for the novice concrete worker, and for homeowners having concrete work done! I wish you could see the re-bar we using on this job in India, some of it 32mm :)

@Concretewiththehauses

2 жыл бұрын

Talking to a guy in India name Marty sent me some pictures of exactly what you’re talking about

I've seen that a lot. Nice work. I know it's a day of rest but I've been doing a lot of online research for modern methods and keep going back to your program. I do a lot of structural stuff so I stay on top of new methods.

@Concretewiththehauses

Жыл бұрын

I’m not 100% sold on fiberglass rebar

@dford8874

Жыл бұрын

@@Concretewiththehauses to be honest with you I had my doubts as well. I really did like that sink you put in for that awesome countertop. I did a farm style monolithic pour countertop sink in place before. It came out real nice using collapsible form. I wanted to thank you again for all that I've learned. It really makes the world of a small potatoes guy a whole lot easier

Very informative video, reminds me of when I was on city council. We had a street where the base settled around 3 feet, it was all fill. They came in and did slab jacking and filled the void with grout under pressure. It did not have rebar because it was poured 7 inches thick! Just wondering if that was a spec built house? Do it as cheap as possible? I have seen it where they also use close-cell foam also. Since the pipe was broken that negates all the above fixes, obviously!

Wow, what a problem homeowner had & glad your cc did not fail. Wonder if original builder's people compacted this surface? 14" is a large 'drop'. Was this house ( subdivision) developed over some former wetland area? Or built on top of former water way drain path? Where are city planning/approval people on this particular house? Have their been other issues like this with neighboring houses?...Hope this is an isolated case & not multi house, neighborhood-of-houses problem. Keep us posted Tom. Thx for your filming 🎥 & showing your solution. Love that pneumatic 'pusher-tamper-large-ball' tool with long handle. Impressive that you have lots of necessary tools 🔧. Bet that heater was handy in such low temp conditions. Great video on fixing a subsidence problem below your ridged, rebar reinforced garage cc slab! Now since it's soo cold outside, let's make another furniture item in your warm garage!🧑‍🔧😊🍷

@Concretewiththehauses

2 жыл бұрын

This builder usually does a pretty good job. I think working in the wood shop is going to have to be put on hold for about nine months work is really starting to pick up Thanks for watching

That's a great job

You can see the rebar

Rebar does not stop concrete from cracking, I am no concrete professional but i can put down concrete its not that hard, My Dad and i have a 24' x 50' x 4" we slab poured in front of my shop for about 48 years now, yes it has a few cracks like all concrete slabs will have and it has no rebar, we pull semi trucks on it and it is still good, my shop 60' x 100' x 4" has no rebar and has no cracks what so ever, I had a buddy concrete professional pour a pad in front of my house garage, 24' x 40' x 4", and he argued with me saying he would not pour the slab without rebar, he said he had some left over from a job and he would put the rebar in for free and so he did. It was poured in the spring and before sommer was over it had cracks in all over the place and some even got bigger the next summer. My grandfather was a professional in concrete and he told me that concrete was guaranteed to dry and then crack. So my question is why rebar in a slab pour, so next time you go to a friends house that has concrete poured in front of his garage see if it has any cracks and also i'm pretty sure it has rebar in it. I am not saying that i know if rebar is needed or not but i am saying it does not keep concrete slab from cracking.Ok concrete professionals go ahead and learn me i am open for discussion.

@Concretewiththehauses

7 ай бұрын

That’s not a simple one to answer. I am a fan of rebar. If it does crack, the rebar will hold it together. Concrete cracks for many reasons. Thanks for the comment.

Good for you and your professional courtesy regarding the site and developer. Hope they're not living over a sinkhole 😬🙏

Typical for a residential contractor to not properly compact the dirt, they are alwaws taking shortcuts or they do not know how to do it correctly. It is hard to imposable to get good nuclear density gage readings when compacting dirt even with the correct moisture content and the proper equipment. Sometimes it is impossible to get compaction with a jumping jake. I hate those things. Best practice is to just build and design things to minimize fill placement. I wish civil engineers and architects would figure that out. One thing to remember, a lot of nuclear density gage operators are not paid well and are under a lot of pressure to the point of being yelled at, so you can never assume that your compaction is being done correctly. I think a lot of guys are just passing everything. A nuclear density gage measures compaction of soil. Soil has to be at the proper moisture to compact properly, too wet or too dry and it can not be compacted. An example is clay soils. You can roll Bone dry clay to a hard glass like surface but it will not be compacted.

@Concretewiththehauses

2 ай бұрын

Thanks for all that that was pretty interesting

Good fix, it's always something!

I do not know about there in Pennsylvania but in the Texas Panhandle a big problem is old prairie dog towns. When it first started they built the business/registrar/student union building with slab on grade in 1929 but they did not know there was an old prairie dog town at that location and over the decades as the burrows collapsed the floor between the foundation started to sink and ended up about four inches below the base boards. When they built new buildings later they would dig out the footprint of the building about twenty feet deep and then return the soil and pack it down very tight and top it off with cliche. After that they would start the new building.

Hi Tom....The use of ground penetrating radar (GPR) used over the entire surface of the existing concrete floor slab would have identified the precise locations and the amount of settlement under the entire slab. Pumping flowable concrete fill under the portion of the existing slab that was not demolished would also help support the remaining floor slab.

@JohnSmith-tv5ep

2 жыл бұрын

Hate to have to bust that out if it did settle more! Lol

@ryanbrausa4325

2 жыл бұрын

When I was a kid, the ground under PCH in Laguna Beach was settling or eroding and the city contracted a guy to come out with a trailer mounted pump. He cored a few holes and bolted in some sort of flange that he could attach to. He connected his hose and started pumping. 10 trucks later, the road went from slumping to domed. It was impressive to watch that V8 powered pump lift the whole road.

Great job guys! In Australia, we call them skirting boards.

Who stole the dirt under the floor call the cops

Tom, your workmanship is top notch! Whoever prepared the base should pay the bill, that amount of shrinking is 100% on the other contractor for not compacting the fill.

@danwalters4865

2 жыл бұрын

Todd you ever been to court over cracked concrete?

I have filled a lot of garage floors on new home builds and we always compacted in about 8" lifts except for the foot close to the walls for just that reason. I would imagine the builder would have been the one that had to foot the bill for that job. I worked on a job that the suspended slab collapsed in the middle of the night. The home owner heard the noise and walked in the door from the kitchen to the garage to see what the noise was and fell 8 feet . He got a little busted up.

@Concretewiththehauses

2 жыл бұрын

I would bet more than a little. Thanks for watching

A grade beam across between that existing concrete and the new concrete might have been a idea since it looked like that dirt fill wasnt compacted at all either. By the way it was going down when you were compacting it !! The grade beam could have added alittle insurance !! Just a thought !

At least they knew who to call to fix and fix it right 👍

Great video on how not to do something. Great repair. Stay safe.

Been there done that. Builders that try to push the process faster than make sense are playing Russian roulette.

Doesn't look like your typical garage pretty fancy.

Had a contractor out here like that in 2000, we made thousands of dollars for his lack of attention to details,great video Tom

Yet another great job by YINZ guys Be that won’t sink again! Thanks for sharing Stay safe Have a Day

Glad that didn't fall back on you for responsibility.

@Concretewiththehauses

2 жыл бұрын

Absolutely me too

What period of time passed for that sub-base to drop so far? That owner is lucky to have you available to fix his problem. You've got all the right tools for your business, like Mike Morgan has all the tools for his. I enjoy watching each of you because you're both so good at what you do. 👏

brrrrrrrr 7 degrees, when that was filmed it was 80 here, great job as always

I had my garage floor raised by a contractor using mud jacking... they forced stone dust and water mixture under slab that had sunk over years... the house is over 60 years old. the slab is still solid and not cracked... they drilled holes and injected the mixture... i had also explored the use of foam before deciding to use the stone dust mixture. I has stayed solid for the last three years

@d.a.ballou9740

2 жыл бұрын

James Jensen: Any idea of an approximate cost for something like that? I have a 30 'x 30' barn floor that was cut into 9 10 x 10 sections that are no longer even due to some of them sinking.

@jamesjensen5000

2 жыл бұрын

@@d.a.ballou9740 I’m sorry but I don’t remember exactly what I paid... but it wasn’t too much... I’m sure there are contractors nearly everywhere that can do such work and give estimates... I would not recommend the other process that uses foam... it is said to deteriorate... while the stone dust stays solid. It might be that the stone dust is actually ground up cement from demo jobs but I don’t know much more

@d.a.ballou9740

2 жыл бұрын

@@jamesjensen5000 No problem. I was just trying to get some idea, from someone that has had this done, as to whether they thought the price they paid was reasonable, or really expensive. Thanks for the reply and the information about using a foam product.

I had this same thing happen in my garage. I am going to have floor replaced. The first guys that did work when house was built did not use rebar. House was built 30 years ago. Ron

Seen this before; actually found a company that pumps in 2 part polyurethane foam that works well. They can actually use their system to raise concrete as well which was helpful in leveling out some old unevenly settled concrete. While they weren’t cheap I’m guessing they were probably less expensive than this.

@Concretewiththehauses

2 жыл бұрын

Builder looked into that a little bit it is pricey

@libertarian1637

2 жыл бұрын

@@Concretewiththehauses: When I had it done it was the cheapest option; it has the added benefit of being 100% waterproof as well as being adhesive in nature which actually helped to stabilize things more. Seen this issue a few times, the garage isn’t bad when it happens in a basement costs get expensive to do it any other way. Though it can very depending where you are, in NY labor costs dwarf the material costs but in some place where labor is cheap or cheaper it may be less expensive to re-do the concrete.

Was the house built at the same time? Makes me wonder if they missed compacting under the foundation/slab as well..

1:32 Do you ever work with RCC ? that's the first thing that came to mind as you're describing the problem.

Could you have put pillars in. Sometimes we use 10 inch pipe 4 feet deep every 5-6 feet to support concrete in case sub base settles.

@Concretewiththehauses

2 жыл бұрын

In the beginning yes now I feel the settling is all done

Great job as always to you and your crew What's the best type of compactor to use? I'm getting ready for my garage floor to be poured and recently had shale brought in as fill. I've been driving over it with my tractor

@Concretewiththehauses

2 жыл бұрын

I have two Makita’s and a stone they work pretty well for me they are quite old and still run good thanks for watching

You guys are very impressive. Thank you for the response to my email.I appricated it greatly. I look forward to the upcoming season. Have a wonderful day.

should've demoed the entire garage floor, but good job ! 👍

look where the rebar is. It should be in the middle of the slab. This proves not using chairs and pulling the bar up during placement is a joke.

Wow, what a mess. Amazing job. Just curious how old the house is.

@Concretewiththehauses

2 жыл бұрын

Just a couple years maybe four

I’ve done carpentry work for developing companies that you water around foundation s so equipment doesn’t crack the block work

Sadly the owners expected the job to be done the first time. There are many craftsmen who advertise as professionals but really they are not even amateurs. You know what you are doing and you are able to repair a bad job done by the original contractor. I am sure that the owners will appreciate the work that you do every time.

I would be nervous if I was that homeowner, I hope they don't have problems in other parts of the home.

This is a very interesting and yet concerning video. We have a very poor driveway base that turns into a mud mess as the season changes, even after ten years. We live in Central Elgin County Ontario (Canada). We are currently getting quotes on a cement pad approx 40 feet by 30 foot in front of double car garage. What should be be looking for as we get quotes when it comes to rebar and concrete depth ? Is there a standard diameter and grid section ? We have been following your channel since you started making videos after working on the Morgans. You have a great channel and we are learning quite a bit from your concrete work to your wood making projects, very refreshing. Any suggestions would be appreciated.

@Concretewiththehauses

2 жыл бұрын

This is one of the reasons I started this channel I’m glad you asked. Driveway should be poured at a bare minimum 4 inches thick 5 inches is better as you get to the street were UPS trucks delivery trucks could nose in about 6 inches thick. I recommend at least 4000 PSI concrete. We use fiber mesh and half inch rebar and often times will put wiremesh in as well it really does not up to cost that much on the projects. The rebar make sure you hit your troubled areas a little more I would say at least a 4 x 4‘ grid for standard car and pick up traffic and never forget a good concrete sealer sorry for the lengthy reply another good idea is to talk to your local Redimix supplier and see who they recommend for install thanks for watching good luck keep me posted

@JaKe-bd2fq

2 жыл бұрын

@@Concretewiththehauses Thank you Tom. That is great feedback. It is awesome for your quick response and information. You are a true professional.

Was it water that undermine it 🤔

Do you ever use that fiberglass Corning rebar

@Concretewiththehauses

2 жыл бұрын

I haven’t yet but I am going to try them this year I’ve heard good things about them

What do you think of road mat reinforcement under a garage floor?

@Concretewiththehauses

10 ай бұрын

Good, but also put some half-inch rebar in there with it

Looks like the old snow and ice backfill wasn't the best quality!!

Estimating concrete must be sketchy, not knowing how much was going to flow under the existing floor.

I’ve used one those jumping Jack compactor and you definitely don’t want your face over top when starting. LOL !!!

Just curious can you use a company that uses spry foam to raise or fill in that gap for a more cheep fix if need I’ve company’s raise slabs in videos

@Concretewiththehauses

2 жыл бұрын

We wanted to remove the two pads in the bad area so we could really compact after four years the settling was done just wanted to tighten the area up for the new concrete

Is there not a structural foam that could have been placed under the undisturbed slab?

@Concretewiththehauses

2 жыл бұрын

Just decided to demo and compact and Re pour

Could expanding foam be injected down there to fill the gap ?

@Concretewiththehauses

2 жыл бұрын

I could but we went this direction so we could compact the troubled area

Howdy Tom, just curious if you have nicknames for your compaction tools? We called the plate compactor like yours "Jumping Jack" and the pneumatic tamp "Toe Beater". Have A Day! ;~)

@Concretewiththehauses

2 жыл бұрын

Same jumping jack toe breaker or jawbreaker Funny thanks for watching

Do you think this was a failure of improper back filling or material or both ?

@robertmyers461

2 жыл бұрын

He actually said that from what I gathered he laid the creet but had nothing to do with the foundation and he pointed out the problem was they didn't compact the base enough for the soil conditions they was dealing with

@robertmyers461

2 жыл бұрын

But they came in seen the shit they already knew was gonna happen and did an awsome job they did not point them out but did the best ever job fixing it tookout the least possible side packed under better filled then finished with top quality work hello just watch a couple of Tom's vids and it just shows in true colors 😉 👍

TOM, Was that settling from the backfilling done in the winter time? Then after the build, the ground sunk due to thaw?

@lescaylor7211

2 жыл бұрын

With it being inside a garage I would say the sinking was mainly from the ground in the garage not being compacted after it was dug up for the build.

@Concretewiththehauses

2 жыл бұрын

I’d have to look back and see exactly when we poured it it’s just a blur that long ago

wait, isn't concrete guy responsible for compacting the base?

@Concretewiththehauses

2 жыл бұрын

We plate temp . it’s filled in when we get there

Why don't you insulate the slab if that is a heated garage?

@Concretewiththehauses

3 ай бұрын

Sometimes we do around the perimeter but that’s usually it

What about pumping a flowable fill into the voids?

@Concretewiththehauses

2 жыл бұрын

I believe the builder looked into that and decide to have us do it this way

@d.a.ballou9740

2 жыл бұрын

What does something like that cost?

@classicadirondack

2 жыл бұрын

@@d.a.ballou9740 Better to ask Tom Hause or concrete company

This is where pouring above the foundation wall bites you. Should've let the mud jacker come in. I've ran into this hundreds of times, I either tear it all out, or I walk away. It's going to settle more in the future

@Concretewiththehauses

2 жыл бұрын

It has been there 4 years plus we did more compassion I think it’s done settling

I’m curious why you didn’t wire-tie the or all of the rebar in the new floor.

@Concretewiththehauses

2 жыл бұрын

Not sure what you mean all the rods were tied

@rickwendling5735

2 жыл бұрын

@@Concretewiththehauses That's reassuring. I did see one of the guys stepping on what appeared to be an untied rod.

How old is slab. This has to be a lawsuit.

Vibrator?

@Concretewiththehauses

2 жыл бұрын

Sometimes

Sine the floor was in such goos shape, why not pump jack or fill the void with concrete pumped into a hole or holes?

@Concretewiththehauses

2 жыл бұрын

We had talked about that possibility that still does not compact the ground as well as that was pretty pricey

I wonder if using the spray foam would have been way easier and maybe cheaper? They use it to raise concrete, but here you would just want to fill the void

@Concretewiththehauses

2 жыл бұрын

We did look at some other options but felt this was the best approach

Whoever built that house should not be in business. Complete failure of the foundation due to poor preparation.

@Concretewiththehauses

Жыл бұрын

I know them they’re very good builders just had some settling

Have you ever used fiberglass rebar and is it any good or not

@Concretewiththehauses

2 жыл бұрын

I have not used them yet they’ve been in my area for about three years maybe four years just haven’t tried them yet I’ve heard good things about them

@robertmyers461

2 жыл бұрын

@@Concretewiththehauses I have watched O'Dell concrete on KZread and don't think he is as good as you 😉 but he keeps talking about it and says it don't rust but that's all he ever says like too much and says it's cheaper and ok we are in pa and I've seen alot of concrete failure but never seen rebar over rusted plus you can get coated rebar I don't know it just seems like on his vids he over states the fact that it don't rust

@robertmyers461

2 жыл бұрын

@@Concretewiththehauses hey if you want to be really silly fun watch the best of the west concrete on KZread lol he don't know shit and is just so opinionated like he is the shit lol its just obvious he don't know shit like the houses lol you guys are the best and do awsome work 😉 😄 and thank you for it 😄 not many companies left out there with the experience or pride or expertise that you bring with generations 😄 😊

@Grendelbc

2 жыл бұрын

@@robertmyers461 You're in Pa.? Go look at the underside of an old bridge. Bet you'll see areas of broken concrete and exposed, badly rusted rebar. Rust over time is the big problem with rebar. The rust expands and cracks/breaks the crete. How fast that happens depends on how much moisture it's exposed to. It's a slow process that takes many years. Coated rebar gets chipped and allows rust to set in and actually spread faster. I think standard rebar will eventually be phased out in favor of newer types that won't rust.

@robertmyers461

2 жыл бұрын

@@Grendelbc ya hay I know all about it I'm retired from penndot so ya I can see the benefits of no rust but is it strong here in pa we have fibercon they use it to build airport runways with no rebar and no tie costs and is stonger than rebar and is made with stainless hello n rust

you think the gravel just settled, and did not wash away under ground some where

@Concretewiththehauses

2 жыл бұрын

Just settled

Holy cow…! I would never have imagined something like that…, sinking/settling that much…. That is just crazy.

How could the base have settled so much to have left such a void ? 🤔

@michaeldowling6999

2 жыл бұрын

I was thinking the same thing. The builder certainly should have used re-bar, but even if they did, not sure how that'd prevented the settling of the base.

@GunpowderandFreedom

2 жыл бұрын

The subfloor wasn’t compacted when it was filled in and settled over time

Nice paw print hat... have you been converted to a PSU fan???

@Concretewiththehauses

2 жыл бұрын

I still owe too much money to Pitt

Omg it's still compacting while that compactor wtf did that crew do just poor on uncompacted soil

The owners were very lucky more damage didn’t occur to their home. Certainly rebar is very important as you indicate…where I can I also use Forta Fiber just to make slabs stronger. For a little extra work preforming the compaction process, none of this would have occurred….Terrible work!!

@Concretewiththehauses

2 жыл бұрын

I’m not making excuses but you do realize it was filled in when we got there

Tom, would it of been better just to re-pour the whole pad. Looks like you replaced half of the slab.

@Concretewiththehauses

2 жыл бұрын

Didn’t see a need the concrete was in such good shape we replace And compacted the bad area

It won’t work. You should have dug a 3’x3 pier all the way Down to original ground.. why did you not take it all out? What was that Diamond in the floor for? Don’t you see a problem there?

@tnolan3176

2 жыл бұрын

That diamond is the floor drain !

@danwalters4865

2 жыл бұрын

Here’s the only way you can be sure the Settling is done. Tear it all out than put water all over the fill in the garage. With the fill/dirt settling enough to break the plumbing pipes you know the fill in the garage was junk material....the steel would only hold it up for so long. To hold. Concrete up where a car sets on it you can only span 18’8” and the concrete would have to be 8”thick and 2 layers/mats of steel the bottom steel every 8” an and the top mat of steel every 12” . The only reason it didn’t fall in there was still some ground the concrete was setting on that hasn’t settled yet. steel every 2’ even 1’ will just help it from cracking and spreading. In this case the garage walls kept it from spreading and cracking.

While speaking with a neighbor 20 years ago, I happen to place my foot on top of a Fire Hydrant in front of his house and watch as it moved roughly 2 inches to one side. While discussing it with the neighbor, he took me over to his Driveway and showed me a crack that he said for years he had been trying to fill, but everything he put in it disappeared. I suggested he call the City to report the problem because water if left to run for years can erode massive amounts of dirt. When the City showed up and started to replace the Fire Hydrant they found a space under his Driveway that a small child could have walked through. Amazing his 1963 impala never fell through the driveway nor did his 1953 Buick Special. I wasn't home when the Fire Hydrant was fixed but you can bet the City never fixed the damage it caused under the Driveway, (the length of the driveway, 40 feet).

@Concretewiththehauses

2 жыл бұрын

That’s amazing two years ago maybe three years ago now we had a bus fall through our street here in Pittsburgh because of that same thing thanks for watching

Have you considered using "dirt mud" that can be forced under the concrete floor to fill in the voids? My daughter had this mud jacking done to her front stoop and sidewall to fill the voids under her wall way when it started to settle.

@Concretewiththehauses

2 жыл бұрын

With the compaction we did and the added rebar I feel we’re good

Your a standup contractor, but what about the rest of the house? I understand that you only did the garage, is that all they're fixing? If I was the homeowner, I'd be very concerned that more of the same wouldn't be happening in different areas of the foundation.

@Concretewiththehauses

2 жыл бұрын

If you knew the builder it would be OK he’s very meticulous and one of the better builders in the area

@joyfilters

2 жыл бұрын

@@Concretewiththehauses well, he hired you and that speaks volumes. I'd still have sections of the slap cored and checked, just sayin... lol

So that's your floor you and the boys poured but you had nothing to do with the base prep??

@GunpowderandFreedom

2 жыл бұрын

Correct. When we show up to a job like this, it’s already filled in with dirt or whatever else the excavation company uses. We flatten it out, add however much gravel we need and then pour the concrete

@Concretewiththehauses

2 жыл бұрын

Correct all we do is play temp the top

Did anyone run a scope/camera down that drainpipe? I would think that 14" of subsidence would be a red flag for a bigger issue - like a broken pipe farther down the line and out towards the main hook-up (or leech field if it's a septic system).