Landscape Drainage

by Matt

This is a question about landscape drainage.





I have a landscaping drainage issue. I know this is short notice but if you could get back to me as soon as possible I would greatly appreciate it! I really enjoy your site and you
have helped me tremendously!

I am closing on a house on Friday morning. It is a brand new construction, but the back yard slopes down
toward the concrete patio, which is 15X20. The patio is connected to the house. The slope
is about a foot high measuring about 25-30 feet from end of patio to end of property.

Is this sufficient for landscape drainage? The builders say it is up to code but I do not believe them...

Thank you so much.

Matt

ANSWER

Congratulations on your new home! I am glad my site has been helpful.

I am not sure I understand what you mean when you say that the slope is a foot high. Do you mean that when you reach the end of the property to the rear, the land is one foot higher than the grade at the patio...or
something else entirely?

Could you please explain this and I would be
happy to give you my opinion on your lawn drainage possible problem.

Susan


From Matt

Sorry I really didn't know how to explain it but how you stated it is correct. I went again last night to measure and it's 14" higher in the
back yard than the back door at a 30ft distance from back door to end of back yard... I hope this helps you better understand.

Thank you so much for all your knowledge!

ANSWER

Hi Matt,
Ok. The way I understand it now is that your rear yard is sloping from the rear property line towards the patio. It is one foot higher at the rear property line than the patio elevation. I'll assume this is
correct.

A couple of things...
Land should not slope towards the house without taking into consideration the landscaping drainage, where the water will go and allowing or designing for it. However, if your land also slopes to the side and is graded to take the water away from the patio, this would be acceptable. If not, in my opinion, a couple of things should have been done or should be done now.

1. A drainage swale can be created. Land is graded away from your patio for a distance of about 4 or five feet. Since the land is already slope towards the patio, a "ditch" is created which runs parallel to your patio. It should decrease in elevation from one point to the next, so that the water is directed elsewhere to a lower area on your property.

2. A drainage pipe can be installed along the patio perimeter. This would be a perforated pipe with holes in the top. It would be wrapped in filter fabric to keep any dirt from getting in and a decorative stone should be laid on top. The pipe should be sloped and lead to a lower elevation on your property.It might connect to a solid pipe and be led underground to this lower area.

3. Land can be graded to a lawn drain which would connect to a solid pipe, leading the water elsewhere.

If you do not have a lower area, a drainage pit can be installed. This is akin to a large drum with holes in the sides so that water can percolate out.

All that being said, your slope is at about 3% which is not so terrible.
However, I would still have the builder divert the water elsewhere for proper lawn drainage.

I hope this was helpful and good luck. If you have further questions,
let me know.

Susan

Landscape Grading Near House

Because of the large amount of snow we had this past winter, we had water seep into the garage floor in areas. If I slope the earth away from the garage,would this solve the problem of leakage into the garage floor in the future?

Thank you.

PS. This is the first time it happened!

Drainage Swale

by Cathy

We have a swale at the back of our yard that doesn't grow grass. It is rather "mucky" and very unattractive. Any suggestions to make it look nice would be appreciated.

Thanks,
Cathy

Landscape Drainage Problems

by Jenny

My sister-in-law recently purchased her 1st house. The home inspector said there was some negative grading problems in the back of the house that need to be fixed. Also she had the under ground oil tank removed and put above ground.

Now there is water coming into her basement in that area. I am assuming because it also now needs to be graded properly.

Lastly the previous owner had changed the back door from the side of the house to the back. In doing so they left an open hole next to the house where the original stairs existed. We are hoping to be able to get some free fill dirt (no money left) and fill in the where the oil tank was replaced and fill in the hole where the stairs used to be.

The area on the side of the house is approximately 6 to 8 feet from the house to the neighbor's small stone wall.

How do we make sure this is graded properly away from the house to stop the water that is now coming in?

I was also thinking we might want to make a swale close to the stone wall to channel any water towards the front of the house that has a natural downward slope towards the street.

Any help would be greatly appreciated since we can not afford to hire someone and need to stop the water from coming in.

water runoff on north side slope next to house.

by Lonna Phelps
(Salem, Iowa)

grading and drainage

We have a walkout basement. On the north side is a 12' long slope. We have built a retaining wall on the north side of the walkout basement. We build 3 tiers on the 12' foot slope with large tumbled belgian stones about 8 feet out from the cement foundation of the house. We used weed fabric and put rock between the large stones.

The first year (this was a new house)the ground settled and we had to rebuild about 3' out from the foundation. This year after heavy rains, the water ran under the fabric and stones and washed out an area under the stones and rock. (The dirt went into a gentle slope by the retaining wall). So of course the stones settled even more. We are not sure how to solve this problem. Would shrubs planted next to the foundation hold the dirt in place? We have considered putting a 2' deep area of cement at the top of the slope so that the water would go over the stones and rock and not under it. It appears that only about 3' out from the foundation is being affected. Any advise would be appreciated. Thanks.

ANSWER

Hi Lonna,

The right way to grade this area would be to slope the area away from the house. I realize that your land slopes downward along the house foundation, but it can still be graded so that the ground is higher at the foundation and gradually gets lower as it moves away from this area. (Sideways) This can be graded at a minimum of 5%, or 1/4 inch per foot. That means that at the area that is five feet away from your house should be a minimum (can be much more) of 1/4 inch lower. I say five feet because the land should be graded away for at least five feet.

I am not sure how your land is beyond what is shown in the picture. Does it slope, is it flat, etc. This would determine how the land is dealt with once it gets into this area. You might need to create a swale or have another solution so that all water flow properly.

As far as planting shrubs, that would also help. Once they get established, the roots will absorb a fair amount of the water.

Landscape Swale At Road

by Pat
(Oregon)

We have a landscape swale at the road... between the front yard and a private road. Mowing it is awkward due to the slope. Do you have any ideas for landscaping that will be low maintenance but nice looking?

I sure appreciate websites such as yours. I live in Oregon.

ANSWER

Hi Pat,
Swales at the road are a problem in Virginia also...hard to mow and
untidy looking.

It all depends on your particular landscape swale as to how to improve it. There
are solutions, but many create a lot more maintenance.

1. Create a dry river bed with decorative river rock and place low
maintenance plantings at the edgings.
2. If the grade allows, sometimes you can fill it slightly to make the
slope less severe.
3. Raise the grade and install a pipe underneath. This is a solution
that is more costly and complicated and will most likely require an
engineer.

I am working on a design where I created a walk from the street to the
front door. I designed a wooden bridge to go over the swale, and planted
along the sides with a combination of river rock and plants. It doesn't
eliminate the swale but I worked with it to foster an interesting
design.

I'm glad you are enjoying my site!

Susan