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Thread: Regrading

  1. #1
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    Oct 2010
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    Default Regrading

    Hi, we need to do some regrading underneath our deck to prevent water getting into our basement. After one fierce storm that gave us over 3 inches of water outside, some got in. Not a ton but with a finished basement, this is a good DIY to prevent issues in the future.

    But my question is how do we exactly do the regrading. Steps, materials, tools? Do we use whatever tool to slope the ground more away from the foundation? Do we need to do the entire area underneath our deck or just enough to get away from the foundation? We also saw in Lowe's bags of rocks for regrading--is this better than top soil or whatever else we could use?

  2. #2
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    Default Re: Regrading

    Rock is not a good choice for a couple of reasons.
    1 - It creates a porous surface that water is going to penetrate anyway, rather than a barrier.
    2 - If you ever have to get under the deck, you've now got rocks to crawl on - NOT FUN!

    Regrading the soil shouldn't be too difficult with regular digging implements. If you're working in tight quarters, get yourself a camping shovel, which is about two feet in length and easier to work in a confined space. If you've got hardpan soil, this is good for getting the water to drain away from the house, but bad to have to dig in. Rent yourself a rotohammer with a spade and chisel tip. This will make digging a breeze.

    If the space under the deck is particularly tight, you can remove sections of the deck boards to gain access more easily.

    You only need about a 1/4" per foot of slope to get good drainage away from the house.
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

  3. #3
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    Default Re: Regrading

    The space under the deck is not tight necessarily but we have to be on our hands and knees to do whatever is necessary.

    But with the regrading, how is it actually done? We dig and remove dirt or we dig and like hoe the slope down? So what is the actual process/steps to the regrading?

  4. #4
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    Default Re: Regrading

    It's kind of hard to say, you just get in there and do it. The thing to keep in mind as you're going is where your high point and low points are. You don't want to over dig. Probably the easiest thing to do will be to set guides and work off of those references.

    Have you ever set concrete forms? Do a similar thing here. Set 1x4's on edge at the correct slope, then use them as your reference for how much to dig by installing cleats on each end of another 1x4 on edge and letting it hand from the reference 1x's.
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

  5. #5
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    Default Re: Regrading

    Quote Originally Posted by bculp View Post
    Hi, we need to do some regrading underneath our deck to prevent water getting into our basement. After one fierce storm that gave us over 3 inches of water outside, some got in. Not a ton but with a finished basement, this is a good DIY to prevent issues in the future.

    But my question is how do we exactly do the regrading. Steps, materials, tools? Do we use whatever tool to slope the ground more away from the foundation? Do we need to do the entire area underneath our deck or just enough to get away from the foundation? We also saw in Lowe's bags of rocks for regrading--is this better than top soil or whatever else we could use?
    As Sprucey says ---- Clean rock usually sold at home centers is not for regrading. Clean rock allows water to percolate through which defeats the purpose of grading away.
    Top soil is generally not recommended since it is a loose soil which will allow water to drain through --- it is better than clean rock. Besides, it would be a waste of top soil under a deck and would create a nice fertile haven for weed growth. If anything, if you are paying the extra price for topsoil used in grading then use it for planting beds or a lawn.

    Soil that's called "fill"which will have less organic material and depending more clay. This type of soil doesn't allow the water to drain through readily which allows it to flow down the sloping needed.

    Crusher run or 1/4 down is ideal for gradeing issues. The stone dust compacts when wet allowing the water to flow nicely.

    But with the regrading, how is it actually done? We dig and remove dirt or we dig and like hoe the slope down? So what is the actual process/steps to the regrading?
    If the ground under the deck is sloping toward the foundation , this is referred to as a negative slope. All you need to do is shovel as much 1/4 down material as need to provide a slope that runs away from the foundation ( known as a positive slope ). As Sprucey mentioned -- you only need a minimum of 1/4 inch per foot of positve slope away from the foundation to effectively keep water flowing toward the foundation.
    Depending on your site conditions you may only need to grade about four feet from the foundation outward.
    Take a four foot level and lay it on the ground --- you'll see it likely tilts toward the foudation. Raise the level until until "level" --- measure the distance from the bottom of the level to the ground --- add an inch --- that will indicate how much to buildup around the foundation. Then gradually work away from the foundation and rake the fill sloping away .
    "" an ounce of perception -- a pound of obscure "
    - Rush

  6. #6
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    Oct 2010
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    Default Re: Regrading

    Thanks for your responses. This type of job would be brand new to me as we are new homeowners and as such, DIY would new as well.

    By looking at it, I would say the ground is more even with the foundation than sloping towards it. Again, the water in the basement happened once and it was a huge rainstorm back in late October/early November here in the Philadelphia region. This is the only time we have ever had water in the basement on this side of the house (the other side has a sump pump but has never had to be used or set off).

    When you say 1/4 you only need a minimum of 1/4 inch per foot of positve slope away from the foundation, does that mean I just shovel 1/4 inch over the 4 feet you say is probably all we need to grade away?

  7. #7
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    Default Re: Regrading

    For clarity, an apostrophe is used to signify 'feet' and a quote mark is used to indicate "inches".

    1/4" per foot of slope, that means for every 12" of linear travel, you want the ground to drop by 1/4". Yes, 1/4" would be the minimum recommended slope.

    Get yourself a level at least 2' in length and a board as straight as you can find that is at least 8' in length. With the board on edge and the level on top of it, you'll measure what your grade currently is and how much it needs to be adjusted.

    To make things a bit easier, you can use a screed board. All materials must be as straight as possible. For this you set side boards at the proper pitch on either side of your work area, say a span of maybe 5' to 8'. Drive stakes into the ground and using screws set the bottom edge of the side boards exactly as you want the grade to be. Then you make your screed board a few inches shorter than the distance between the two side boards and tack a stick to the top edge of the screed to hang it from the side boards. Now all you do is slide the screed down the side boards, clearing the dirt until it just touches the bottom of the screed.

    You want to be careful not to remove too much dirt around piers that may make them unstable, they should be set below the frost line, which means that the small amount of dirt you'll remove should be inconsequential.
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

  8. #8
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    Oct 2010
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    Default Re: Regrading

    ***, ok. This feels very complex for what it appears or seemed like an easier job to do. I thought we could just rake the dirt to create a new slop away from the foundation...

  9. #9
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    Default Re: Regrading

    Depends on how much slope change you need to do and how hard your ground is. You will still need something to measure your work with and make sure you're not compounding a problem rather than fixing it. In this case, then a straight edge with a level and a rake will be all you'll need
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

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