Concrete Patio Project- NEED HELP


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Old 02-18-11, 09:00 PM
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Concrete Patio Project- NEED HELP

Hello, my wife and I are thinking about pouring our own concrete patio. The space is located under a deck, in an area with poor drainage. I suspect that we will need to install a system to improve drainage. I am posting with the hopes of receiving the opinion of people with experience on similar projects. Take a look below at some photos of the location.



The photo shows where we would like to have the concrete pad. As you can see it is a 12í x 12.5í area.



This photo shows how we would like the finished patio to look. It is hard to see; however, the portion in between the post and wall on the right includes a half circle extending into the yard.



In this photo you can see the area under the deck steps. I am unsure of the best way to proceed with the slab in this area. We would like the slab to encompass the steps but are unsure how to proceed where the steps meet the ground.



This photo gives you an idea of the drainage problems we are experiencing. Due to the high spots in the yard (designated by brown circles) we have pooling water in the area marked with blue. I donít know if it is better to lower and re-slope the high areas or raise the low spot.

I appreciate any advice on how to proceed with this project.
 
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Old 02-19-11, 05:03 AM
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I know this is a DIY forum, but unless you are moderately experienced with concrete work, this one is probably best left to a pro. The lack of accessibility, position in a corner, one side against a wood curtain wall, and working around obstructions such as the stairs all make this a harder job than is typically done by a homeowner. That's my best advice: hire it out.
If you "have to" do it yourself, make sure you excavate enough that you can pour at least 4 inches concrete on top of a few inches of fill stone or sand. Pour the concrete up to just under the door threshold in back, and slope it toward the front. The slope should be about 1/8 to 1/4 inch per foot. The concrete will need to slope away from the walls of the house (both directions). When everything is said and done, the lowest part of the slab, which will be the front left corner, should be at least an inch above the ground to allow water to escape. If it's level with the ground or lower, the water will pool there.
You also need to dig under the steps, or cut them off such that they ultimately rest on top of your slab. Don't pour around them as they are now. Make sure you properly install flashing if you're pouring up against wood on your house.
When you're done, grade the yard such that water runs off. Whether you cut or fill depends on the water. Good luck.
 
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Old 02-19-11, 08:17 AM
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I agree w/ Pecos. It's a small job, but there are some issues that would best be left to a pro, like he pointed out. Flashing the walls is a must. Level should really be determined by the height of the steps, so that the rise from the slab to the 1st tread is the same as the rise in all of the rest of the steps. Anything else is going to become a trip hazard. From there, the slope of the slab will determine the step height at each door involved.

Grading in the yard is pretty minor. A combination of lowering the high spots and filling the low will cure that.
 
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Old 02-19-11, 12:57 PM
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Yes, as Lefty said, the bottom step needs to be the same size as all the others. It looks like it's a short step now. If you pour concrete, you may have to cut that bottom step off. It just depends on the elevation of the concrete. The door threashold can't be moved, and you need the slope I mentioned for water runoff. The only thing that can be adjusted is the wooden steps.
 
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Old 02-19-11, 01:31 PM
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Just looking at the pictures and not being able to actually measure step heights ect. puts us at a bit of a disadvantage. But based on what I'm seeing, you should be able to get the riser height of the steps right and still be fine at the door threshold.

There is a good range of what is a comfortable stair riser height. I "shoot" for 7", but anything between about 5-1/2" and the 8" max. that code allows will work. The important part is consistancy between the risers of a set of stairs. Code only allows 3/8" max. between the shortest and the tallest one.

It appears as though you have 7-1/2" risers on the set of steps. That's fine. Your rise from the concrete to the bottom tread needs to be that much as well, or very close to it. When you get to the door threshold, that rise can be whatever it needs to be, and you can adjust the slope of the concrete somewhat as needed to make it work.

Like Pecos said, there is a bit more to this project than just putting down some concrete. It's not at all a difficult job, but there are certainly a lot of details that have to be taken into consideration, and that leaves a lot of possibilities for errors.

If you decide to take it on yourself, plan carefully and don't be afraid to ask questions about anything you're not sure of. It's easy to change the plans, but not so the concrete once it's set up!!
 
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Old 02-19-11, 03:30 PM
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Thanks Pecos and lefty for the advice. I just noticed that the picture of the yard did not post.



This pic shows the drainage issues. The brown circles are the high spots and the blue is where the water pools.

Also, I just went out and measured the steps. From the gravel to the first step is about 4.5" and all the rest of the steps are about 7". I dont know if removing the last step is feasible due to the level in relation to the back door and
 
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Old 02-19-11, 05:49 PM
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clarkpat
That pic posted. Maybe you didn't scroll down far enough to see it.

Now that you pointed it out, I see where the bottom rise is less than the 7" or so of the others in that set of steps. Not a problem, in fact it may even help you. To get a 7" rise on that set of steps will mean lowering the level of the slab. That will give you more rise at the threshold of the door(s). That looks to be a little low. That would mean a little extra grading at the outside edge of the slab, but that's not a big thing. That's just moving a little more dirt around.

Blocking the stair stringers to make the bottom rise become 7" or so isn't that difficult once the slab is in place.

But these are all part of the little details that Pecos & I are talking about that makes this slab trickier than it first appears.
 
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Old 02-19-11, 07:53 PM
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So would the best way to procede be to remove the steps, grade the area, pour the slab, then replace the steps?
 
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Old 02-19-11, 08:31 PM
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I wouldn't REMOVE the steps, I would simply free the bottom of them and pour a small support under them. Once that is cured, attach the steps to the support, then pour your slab up to that support.

Like I said -- this one is tricky. There are easy ways to do it, and hard ways. There are a lot of things involved that could places for an inexperienced person to make mistakes. As simple as it appears on the surface, this one is probably best left to a pro.

Done right the first time, it's quick (except for the drying time involved) and easy. Done wrong, it'll become a nightmare.
 
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Old 02-20-11, 06:17 AM
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Any chance you are aware of said pitfalls and are willing to enlighten me to them?
 
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Old 02-20-11, 06:33 AM
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The potential pitfalls as I see them:
1) The concrete has improper slope and water pools as a result. If water pools against any wood or your house, it will cause damage.
2) The bottom stair ends up shorter than the rest, creating a tripping hazard and code violation.
3) The concrete sets up faster than you can finish it, leading to a bad looking slab. The location of the slab and other obstacles makes this a real concern.
4) Improper jointing leading to shrinkage cracks. If you pour around the steps instead of lifting them and pouring under them, you create 4 places for a crack to originate (re-entrant corners).
5) Once concrete sets up, there is nothing you can do to fix any screwups short of tearing it out and starting over; a very costly process.
 
 

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