Grading around house...

Old 10-27-01, 04:23 AM
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I'm trying to investigate grading the perimeter of my house. In other words, I have bushes and dirt that go right up to the cement foundation, and I'd like to replace that with an attractive gravel border. Two reasons for this - (1) it will look a lot tidier and (2), more importantly, everything I read says that the garden/gravel should slope AWAY from the house for the first couple of feet, for drainage. Currently I have areas where it actually slopes towards the house.

Can anyone point me to a site, or a book, which details (for an idiot) exactly what I need to do? My questions include:

1. What do I fill the gradient with, i.e. do I go and buy some mud/earth/soil from somewhere, and what type?
2. I understand I need some sort of plastic sheeting over the mud/earth - what is this, and what are the requirements for installing it?
3. And do I then just chuck my gravel right on top?
4. Do I need some heavy equipment to compact the soil before I put the plastic down?

As you see, I am clueless and need help in the form of baby steps. Any help much much appreciated.


Old 11-02-01, 02:52 PM
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Location: Acton, Ontario, Canada - Zone 6b
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Hello TY

Surprised Gami hasn't found a website for you yet....but give him time.....

I assume that when you say the earth goes right up to the cement foundation, you mean that it is now at the top of the concrete or cinder block foundation and just below the sillplate and any woodwork or clay brick. If this is the case, you may need to excavate a swale or small trench at least a few feet away from your walls to allow the water to drain away and channel it to a lower area. A slope of at least 1" per foot would be desirable, although you might be able to get away with 1/2" per foot in a pinch - the greater the slope, the less chance water will have to percolate down and get into your foundation. (This is assuming you don't want to put drainage tiles underground along your foundation - a lot of work if you don't have to do it!) If the existing grade is below the top of the foundation you may be able to add material to slope away from the walls. You might want to apply a waterproofing parge over the foundation wall before you place soil against it to help keep moisture from penetrating.

Most of the water causing the problem is probably coming into the foundation area from higher areas (your yard and the surrounding areas), damming against the foundations and moving down and into the walls so by keeping this water away, you should have taken care of the problem. You should not worry about the water which is FALLING on an area which is properly graded to slope away from the foundations as it is very minor by comparison and would drain away from the wall into the swale in a hard rain before it has a chance to percolate down and cause any problems.

Any gravel or stone on top of the earth should not affect the surface drainage as long as it is clean and more or less uniform in size - if the gravel is various sizes from pebbles (or stones) down to fine flours, the fines would settle and form the 'floor' of your slope, possibly forming dams in the larger material and holding water back. As long as the gravel is clear and the soil below the gravel slopes away from the house, the water should drain away also. If you want to keep the gravel (or any hard 'top-dress' material layer) below the top of the foundation, you would have to excavate to the depth you want to put the gravel and then apply your barrier layer. If you want to have the gravel above the foundation, you could thin the layer at the wall or even keep the gravel a few inches away from the wall and keep the earth just below the foundation top. The gravel is really only a cosmetic layer as water will move along the surface of even cultivated gardens as long as it is sloped in the right direction.

A landscape fabric barrier (usually a black, breathable woven material) would separate the soil or earth from the gravel on top and allow moisture to move up or down through for evaporation and to get moisture to any plant roots. Plastic sheeting would probably serve the same purpose, but would not allow water (and nutrients) to your bushes and I think may actually help trap underground moisture below it, forcing it into your foundations. If you are going to use plastic, I would recommend putting some holes in it with a garden fork to allow moisture to move up and down. I don't think plastic will last as long as landscape fabric also, and may need replacing as it breaks down due to freezing, UV exposure, etc. The landscape fabric barrier will be especially appreciated if you decide to remove the gravel later and put in a garden or lawn!

The soil below the fabric should not have to be compacted if it is undisturbed while you excavate and put the fabric and gravel down. If you are going to add earth, it should only require enough compaction to stop it from settling any further - this should be done by adding an inch or so of earth, compacting with a roller, tamper or even by walking on it while applying the force with your heels, then adding more earth, etc...

A clay soil would act as a cap and would direct the water away, but may be more of a problem in the long run... Best to use the same type of soil as is already there - or using topsoil, so you don't have to ammend much if you decide to create garden beds or bring the turf up to the foundation later.

Hope that gets you started

Good luck

Old 11-02-01, 04:57 PM
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Hi Howie,

Um, that should be give "her" time. Actually, I tried, but about all I found was how to keep a basement from leaking.

I haven't had to deal with that problem, so couldn't even speak from experience.

You handled that matter quite nicely.


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