HELP: New Concrete *Driveway* Heaves, causing Garage Flooding

[catalytic]

EDIT: New Concrete *Driveway* Heaves, causing Garage Flooding

Guys, I need your thoughts/opinions/recommendations. In Oct. 2013, we had our blacktop driveway redone with concrete.

- It was put in without the drain grate seen in the photo, but in the winter, the slab right in front of the garage heaved up and caused water to drain into the two garages.

- For the last 2 winters, the slab right in front of the garage heaved up 1.25", cracking this slab at the grate and causing the swale to effectively heave out. Also, the drain grate and drain tile froze, preventing drainage. This caused water to drain into both garages and flooded them so that they have standing water in the winter. It also means that we could not open the hinged doors in the left garage for most of the winter, because they hit the driveway slab.

- To contractor recently returned with an engineer and said that they could not have foreseen the heaving problem, and that they need to rip up the slab closest to the garage to dig and pour a footer that will reach below the frost line. The contractor is quoting ~6k, which is more than the entire driveway cost.

- Before proceeding with the costly footer plan, I wanted to get your guys opinion.

Details:
The whole driveway slopes gently down towards the garage (and towards the swale & drain grate).

The left garage's slab has lip that is 0.6" higher than the driveway in the summer. The right garage's slab has a lip that is flush with the driveway slab in the summer.

Both garage slabs slope towards the garage door & driveway, but water cannot escape in winter because the driveway heaves up higher than the garage slabs.

The high side of the property is the yard to the right of the driveway in photo 1 (where the car is parked in the picture). Along this right side is a 12" deep drain tile of gravel over perforated 4" pipe, which is supposed to take water from the yard to back behind/right of the garage instead of allowing it to drain into the driveway.

 

[NUTTSGT]

Re: Help: New Concrete Garage Heaves, causing Flooding

Would you like the thread title changed to that bolded edit ?

 

[bczygan]

Re: Help: New Concrete Garage Heaves, causing Flooding

Time to shake your lawyer at them.

Bottom line is that everything should work properly. They are professionals. They should have made it so.

What kind of contract did you have?

Bill

 

[matt_i]

Re: Help: New Concrete Garage Heaves, causing Flooding

Maybe I'm looking at it wrong but if the slot drain was working/flowing/open it would solve all of your issues?

If so, I'd work on that. Draining it to the high side of the property into a closed/slotted excavation seems like a big problem. I would send water via gravity to the lower side, no matter how much piping you have to run, to send it out the open end of a 4"+ diameter pipe (grate of course to exclude animals). In the 3rd picture down, my calibrated screen-level says that the low side is where the little stepper pads are. Not sure if the trench drain is sloped down toward the high side, if so you might have to cut that entire part out and repour. If the base of the trench drain could be accessed from the left, then I'd think about cutting that slab only and try to tap the trench, sealing off and abandoning the French drain on the high side of the property as it obviously does not work.

 

[catalytic]

Re: Help: New Concrete Garage Heaves, causing Flooding

Would you like the thread title changed to that bolded edit ?

Yes please!

(You know you spend too much time on GJ when you begin accidentally typing 'garage' instead of other words in a way that garage not make sense...)

 

[sbd4de3]

Re: Help: New Concrete Garage Heaves, causing Flooding

Yes please!

(You know you spend too much time on GJ when you begin accidentally typing 'garage' instead of other words in a way that garage not make sense...)

HAHAHA! I totally rolled on the garage laughing after reading that!!! I've been doing the same thing all garage when talking with my wife!! She was so mad at me she said I couldn't have garage after dinner!

 

[boobag]

Re: Help: New Concrete Garage Heaves, causing Flooding

when the new drive was put in, why wasnt the slope changed so that water flows away from the garage?
that drain you put in front of the garage will always freeze, and collect a lot of water under the ground, which is why the drive heaves.

 

[Bondo]

Re: Help: New Concrete Garage Heaves, causing Flooding

In Oct. 2013, we had our blacktop driveway redone with concrete.

Ayuh,.... Did the driveway heave when it was blacktop,..??

Which ways was the water directed when it was asphalt,..??

Never heard of puttin' a footer under a driveway,....

 

[wssix99]

Re: Help: New Concrete Garage Heaves, causing Flooding

Heaving is normal. All floating slabs are intended to move, so "heaving" should not be an issue if they are placed properly.

... Your slab was not placed properly and is defective. The engineer that came out and looked at the issue is probably not skilled in pavement design. If their contractor brought them out, they are probably a structural engineer and this stuff would not be in their wheelhouse. If they really believe that you need a "footer," then they don't know what they are doing, either. (That again is something that a structural engineer would typically fall back to. A really expensive solution, for a very simple problem - that they aren't used to dealing with!)


The drain makes this thing tricky. The square corners of the drain create what is called a "reentrant corner" in the concrete. As the concrete cures and shrinks, stresses are concentrated around these corners, causing cracks to form and radiate out from them.

- For the last 2 winters, the slab right in front of the garage heaved up 1.25", cracking this slab at the grate and causing the swale to effectively heave out.

If you look at the outside corners of your driveway, the contractor effectively dealt with the corners by putting in extra control joints and one diagonal one, exactly where it needs to be in order to relieve the stress. (The joint going in to the house took the 270 degree reentrant corner and divided in to safe 90 and 180 degree angles and the diagonal joint took the other 270 degree reentrant corner and divided in to two corners less than 180 degrees, also both safe.)

In the middle - they didn't do enough. So, a crack formed at the drain, close to one of the problem corners. The singular piece of concrete between the drains was shaped like a "T", leaving you with two 270 degree reentrant corners at the far edges of the drains.

So your crack likely started from shrinkage stresses in the concrete and not movement of the slab. (A structural crack would probably need a void under the slab.) In winter, the slab will contract more, making the stresses greater - so you can expect these things to pop up more frequently after a really bad freeze.

Also, the drain grate and drain tile froze, preventing drainage. This caused water to drain into both garages and flooded them so that they have standing water in the winter.

This probably made your small crack in to a much larger one. Once water gets in to a small shrinkage crack, it can freeze and push the thing open. Likewise, if the pipe between the two slot drains failed, you could have some erosion in the base of your slab leading to other problems. With your drains spaced that far out from the house, (and warmth) you probably need an electric heater in them to keep ice dams from forming.


Had the concrete company put an expansion joint connecting the outward middle corners of the slot drain, I don't think you would have had any cracking at all. That would have cut the concrete up in to rectangles and eliminated all of the reentrant corners.

You can google a lot of good info on this and also test your contractor and "engineer" with the term. If you get a blank stare when you say "reentrant corner," then you will know instantly that you know more about the situation than they do!

 

[reader2580]

Re: Help: New Concrete Garage Heaves, causing Flooding

Personally, I don't like drainage solutions that involve getting rid of water via underground pipes like this. I much prefer sloping things away for natural drainage. What I see happen all the time with underground drainage pipes is they clog up or collapse over time. If it gets cold in your area the pipes can freeze up.

Sorry this doesn't fix your heaving issues.

 

[Orionrising]

Re: Help: New Concrete Garage Heaves, causing Flooding

I fail to see how a footer will keep a slab from heaving. Proper draining and gravel base however will.

 

[catalytic]

I really appreciate the help, guys. Actually, the reason we had the concrete garage put in is because we were having problems with drainage with the previous blacktop driveway (which was sloped exactly the same way, but did not heave as badly and had no drains). The old driveway had MUCH less severe water issues than the new driveway. We had asked the concrete contractor (1) to leave the driveway 1" lower than the garage slabs so no water could flow in if they heaved and (2) to make the drain grates go all the way across without breaks. The contractor said that a lower driveway was unnecessary, and he showed up only with the 3 shorter grates on pour day...

So, I need your help with:
1. What is the proper way to fix the drainage and cracking problem?

2. Does anyone have a recommendation for a different contractor or a pavement engineer in the Northern Ohio area (44074 -- 35min west of Cleveland). Also, is a Pavement Engineer the right kind of guy to have come look? Is there a county inspector that should look at it, too?

3. How long do I have to get this fixed before it's too cold to work on concrete? Last winter was a flooding & garage-door-blocked-shut disaster, and I need it fixed before I do that again...

Here is a better labeled picture and some more details:
Pic 1 below shows that:
There is a low point near the walkway to the house, which becomes a mini ice-lake in winter. There is a second low point between the two garages.

Water in the drain grate is supposed to drain towards the yard, where there is a drain tile along the driveway 1.5ft deep. The yard is uphill from the driveway, but the drain tile in the yard is buried lower than the driveway. The drain tile has a 4" perforated pipe, under gravel, which takes water from the yard to way behind the garage.





The following pic below shows where the heaves cause problems. Basically, the driveway buckles upwards at the crack, nullifying the swale, which lets water pour into garage #2.

 

[wssix99]

1. What is the proper way to fix the drainage and cracking problem?

I think your cracking is easily solved by putting in an extra expansion joint between the drains to eliminate the registrant corners. The drainage issue is much larger:

If you are getting that much heaving, I'm thinking that you may have a water problem under the slab. The amount of movement you have sounds uncommon. Do you have a gutter/downspout that drains to that low point to the left of the garage? Maybe there is a source of water over there that is feeding the problem under your slab?

Before you do anything with the concrete, it may be worthwhile to consult a flooding/drainage company to take a look at how water is handled around the outside of your house and see if they can give you a good strategy as to how to handle the water on your site at a global level - not just at the entrance to your garage.

3. How long do I have to get this fixed before it's too cold to work on concrete? Last winter was a flooding & garage-door-blocked-shut disaster, and I need it fixed before I do that again...

It all depends on how long the frost holds off. As long as the concrete doesn't freeze for the week after you pour it, you should be OK. You can do things like cover the pavement with plastic, insulating blankets, etc. to protect against overnight frost but you pretty much need to line the project up and then take a look at the weather forecast.