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Question DetailsAsked on 2/3/2014

Garage Floor slope question

Hello,

This is a very dump question. We have an attached two car garage with the size of about 21' X 21'. At a very rare occasion, I measured the slope on both sides of the garage. One side is about 4.5" and the other side is around 5.4".

So I did more measurement in the garage. It seems to be one side of garage floor is a little bit tilt towards the wall, which means on one side, the middle of garage is slightly higher. I also checked the water stain on the floor. I saw on the half side with 5.4" slope, some traces of water stain are towards to the side although majority are towards to the garage door.

Beside one crack right in the middle of garage slab, which has been there since we purchased house six years ago, there is no other large cracks on the floor. Is there anything I should worry about? This is six year old house.

Thanks.

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11 Answers

Voted Best Answer
2
Votes

Is the wall that the garage is sloped toward and adjacent wall of the home?


If not, it should not be of real concern.


Try to keep the water out of the garage with a gasket on the door.



Answered 5 years ago by WoWHomeSolutions

0
Votes

The slope is towards the garage door, not the house. So majority of water are going outside, Just a little goes sideway towards one side of the garage.

Answered 5 years ago by shiyang100

1
Vote

That is fine. The slab is supposed to be slightly sloped to the outside as a default to drain.

Answered 5 years ago by WoWHomeSolutions

0
Votes

But do you think I should do something to correct the slight slope difference on one side of floor so water will not go sideway?

Answered 5 years ago by shiyang100

1
Vote

Probably not.


If the water is not pooling against a wall to the home, you should be fine.

Answered 5 years ago by Davidhughes

0
Votes

Thanks David and WoWHomeSolutions.

Answered 5 years ago by shiyang100

1
Vote

Not a dumb question at all - the only dumb question on this site is the one you had in mind and knew you should ask, but failed to ask and then a problem occurred because you did NOT ask the question.

One thing I would do is consider, on the side toward the house, is what would happen if water did drain to that side. If it would come up against a concrete curb (slab in house is higher than in garage) then no worries. If it would run across flat concrete and under a wall into the house, I would clean along that junction well with a stiff brush (or compressed air if you have an air compressor), then wet sponge it to remove the dirt, and let it thoroughly dry. Then after thoroughly dry, run a healthy bead of 30 year silicone caulk along that edge, running it a good half inch to inch or so up the wall also - that would help keep water from getting into the house if you even have a lot of slush melt under the car, or a broken water pipe or leaking water heater in the garage if that is where your heater and furnace are. If you are going to want to paint the caulk so that seal does not show, be sure to buy one that says it is paintable - will be a latex modified silicone caulk in that case. Probably would take at least two and maybe as much as 5 tubes for that length with a healthy bead plus smearing up on the wall as a water barrier also. You would have to decide whether to buy a couple and see how far those go and then go back for more as needed, or buy about 6 and take back any unused ones for refund. Usually about $10/tube, plus about $15 for a useable caulk gun (don't get the lightest duty sheet metal ones, they bend in use with silicone caulks). If you don't want to buy a caulk gun, then get tubes of Tub and Tile caulk like Dap - they are smaller so will take more tubes, but you just squeeze out by hand. Will not last quite as long but will work, but probably not paintable.

As for the crack in the middle of the floor, almost no garage floors are totally uncracked. One thing I would do, to prevent the possibility of settlement from water running down into the crack, is brush or air clean it out, then caulk it with concrete caulk - comes in a tube like regular caulk (will need a caulk gun for this), but is concrete colored and formulated to be used on walks and driveways.

It is likely that over the years, especially if you park a car in the garage, you will have a longitudinal crack more or less down the center from front to back, and also either one crossways at about the center, or maybe angled cracks taking off the center crack at about 45 degree angles towards the corners. This is because most contractors do not do an adequate ob of compacting the fill under the slab, so the edges end up supporting it around the edges where it sits on the footers, so it dishpans down in the center eventually and cracks as the center settles down - typically about 1/2-1 inch total relative settlement. Since yours is high-centered, sounds like maybe they compacted well in the center, but not around the edges, or maybe did an excellent compaction job under the slab and the footings are settling (which is also common), leaving the slab high centered. As for worrying about crack - unless it opens up more than about 1/4 inch or so, or starts to offset so one side rises noticeably above the other, nothing to worry about.

Answered 5 years ago by LCD

0
Votes

Thanks LCD.


On one side, some water did flow toward it. The floow is against a concrete curb, which is about 1 ft tall at the entrance of garage, and about 8" inside. There seems to be a fine gap (or crack) between concrete floor and that curb, which I thought it is normal since floor was poured concrete after the curb is built. So I am not sure if there will be some concern if water getting under the slab through that gap.

Answered 5 years ago by shiyang100

1
Vote

Good - Detail 12 (the first one) in this link will show what your construction almost certainly looks like - to the right in the diagram is your garage, house to left actually probably looks same as at right. At the garage door looks the same except the curb is dropped down to the level of the top of the slab to allow driving in and out.

http://www.all-concrete-cement.com/mo...

The foundation wall supports the house studwalls, probably built up with concrete or cinder block around the outside, or like the drawing all the way around the house and garage if your area does not have significant frost penetration depth.

The footer supports the house, and is buried several feet deep. The area inside the footer is left high or filled, and the garage slab poured on that. The gap you see around the slab would allow any water in the garage to go down the garage side of the house wall footer, into the area under the slab. Obviously not a good idea to let a lot of water in there, because can cause settlement of the fill. Also, the cinder block walls are not water tight, so if there is a recessed room or basement on the other side of the curb, or a concrete slab with finished flooring on it that would be damaged by damp concrete, it would have the potential to get wet if a lot of water went down that crack - either from garage floor washing or a plumbing leak, if your utilties are in that area.

Therefore, in the ideal situation, you would run the caulk like I talked about along there to seal that edge - use the concrete caulk to seal the crack itself, then either that or silicone caulk to build a bead in the corner and a bit up the wall where water might stand. If there is a chance of much water standing there, then a liquid concrete sealer applied on the curb after the caulking would be the thing to do - probably for the full height of the curb. Plus full caulking around the sill plate on the door to the house. Obviously, not much sense in waterproofing the curb above the sill of any door into the house.

This presumes that the water would start running out the door of the garage (and not cause problems elsewhere by backing up along the foundation) before it would flow over the curb, which sounds like your case. In a situation where there would be a chance of it building up high enough to start flowing over the curb before it started flowing out the garage door, then I might be tempted to leave the crack around outer walls as an emergency drain, and just be careful if I wash the garage floor to keep water from getting to the curb using a broom or floor squeegee. However, obviously better for the house if significant water can't get down into the crack.

If crack is too wide to reasonably fill with caulk (over about 1/4 inch wide) then there is foam backer rod material, looks like this -

http://www.stickyproducts.co.uk/ekmps...

comes in rolls of 10-25 feet - quite cheap. You use the size larger than the gap you are filling so it fits tight, shove it down in about 1/4 inch in your case, then fill the remaining gap with concrete caulk. The backer rod (which is the same as you use in caulking around window frame) keeps you from using up tube after tube of caulk on a deep crack.

Answered 5 years ago by LCD

0
Votes

Thanks LCD.


You are absolutely correct. Detail 12 is exactly what my garage floor looks like. The wall faces externally, so I am not worrying about water getting into the other side of the garage wall. Since we got some snow yesterday, I spent some time last night to check where melted snow went. On the side with smaller slope, everything was fine. Water went straight to the garage door. On the side with larger slope, most went to the garage door. However at two places along the wall as well as that corner, there were some standing water. I touched the floor and could tell those two spots and corner were a little lower so water could stay. Of course, another issue is water, despite of small amount, did drain to the side instead of going straight to garage door as the other half of garage. It could well be like this from the beginning since I didn't see any other major cracks besides the one right in the middle of garage slab, which has been there since we purchased house six years ago.


Answered 5 years ago by shiyang100

0
Votes

LCD,


By the way, I forgot to mentioned, there is a bedroom above the garage. I am not sure if that will make any difference. I think they built the garage as Detail 12. Footing is below the frost line.

Answered 5 years ago by shiyang100

0
Votes

IF you really wanted to, it would be possible to have that side of the garage bush hammered or ground or shotblasted to roughen it, then overcoated with a structural grout overlay so it would drain to the garage door from that side, but to me that would be getting obsessive. Personally, I would not mess with it. I would invest about $20-25 in a broom-squeegee, with broom on one side and squeegee on flip side - looks like this (with the broom handle, of course - this happens to be a replacement part without the handle), and comes in both straight and curved configurations -

http://www.grainger.com/product/KRAFT...

Commonly sold as an asphalt driveway sealer spreader, but good for sweeping the bulk of the water out of a garage, and the squeegee side can be used to scrape the surface most of the rest of the way clean, especially if moisture buildup in the space is a problem. If you seal your driveway with the water-based (cheaper) driveway sealer, if you clean the tool off with soap and water immediately afterward it will be suitable for this job and for future driveway sealing jobs as well (if you have an asphalt driveway).

The amount of water you will get from slush/snow melt off the car should not be enough to cause any damage, but I would not be washing the floor with a hose and let a lot go down the crack - hence my recommendation to seak the crack, though since on outside wall no need to go up the curb with sealant.

The second story has no impact, other than that if a LOT of water went down there and softened the support for the foundation, resulting in a bit of settlement, while it would likely have no structural effect it could result in architectural cracking of drywall and such upstairs, but would take a lot of water (probably a hundred gallons or more at one time) to do that.

One thing I have seen companies do when they have this issue in a warehouse or industrial building, with water moving from melting vehicles to a wall where they had stuff stockpiled, is to use a water absorbent containment boom (NOT the more common oil-absorbent type - it does not soak up water) - then when the water has stopped dripping and has stopped running across the floor, hose the boom off it real muddy and hang up somewhere outside to drain and dry (so it does not mildew) till next needed. Looks like this -

http://www.amazon.com/ESP-30GS34-SB-P...

cost about $0.50/LF, available in lengths from 3 to 100 feet at industrial supply, commercial cleaning equipment, and many hardware stores, as well as many places online from Granger and Amazon to Northern Tool and JCWhitney, among many others.

I would also be sealing that center crack, both so melt water does not run down into it and possibly remove support from the cracked free edge, and also so when you squeegee the standing water out of the garage, it does not go down that crack as you head toward the door with the water.

Answered 5 years ago by LCD




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