Question

Property Grading   QUESTION: I purchase a property and I am looking to grade the yard.    I was told these homes were built on a creek and the water table is really high here and when it rains hard the streets get flooded and backs up to the house.  My house is extra bad because the yard slopes into the house.  In fact much of the T1-11 siding is below or at grade level has to be replaced.  So I am looking for advice on the best way to proceed.

I have attached a photo showing the two sides of the house, a street view and a back yard view.   I want to grade the property such that the water flows away from the house and yard and towards the sidewalk where it will flow to the street.  If I have to I can also install a French and/or yard drain.   I want to make one swell on one side and another swell that goes around the backyard and down the other side to take the water to the sidewalk.  

Some facts first.  The sidewalk is about 6?below my slab.   The house is built on a slab.   Ideally I would like to dig the dirt down to be 6?below my slab to avoid T1-11 rot and termite issues, but I do not think that is possible in this situation.    I would still like to get the grade as low as possible below the T1-11.  The distance from the back of the house to the sidewalk is about 75 feet.  So if I started 2?below the slab I would be able to drop about 4?in 75 feet to the sidewalk, which is not much of a slope.  From the sidewalk to the street there is decent drop, but I cannot lower the sidewalk.  

From the side of the house towards the fence there is about 13 feet.  I was thinking about grading towards the fence, and then create a swell that runs along the side that drops towards the sidewalk.  I read that I need 紨 per foot drop.  So if I went out 8 feet from the house to the swell that would be a 2 inch drop, which would only leave me 2?to drop from the beginning of the swell to the sidewalk.  Even though it would be better than what I have now, is that enough drop to even work???  Plus I want to grade the back with a swell to take all the standing water in the back to the sidewalk.  I am not sure how deep and how wide I should make the swell.  

Another question is what would you recommend as the best equipment to do this job.  There are lots of tree roots.  I have talked to people with tractor front loaders, bobcats and mini backhoes.  I would think the mini back hoe would be best for this situation, but wanted your opinion.

Any help you can provide would be appreciated.  

Thanks in advance,

Robert

ANSWER: Hey Robert:

Sounds like a big project and you seem to have read some of my previous answers to similar questions. To start with you need your grade at least 3-4" below the T-111. Also I would start plans to replace all T-111 with hardi-siding (Cement board) as funds become available. T-111 is just not a good long term solution for any house. You can do one side at a time if money us tight. Siding for your whole house should be about $2000-$2500 if you do most of the work yourself.

As for grading sounds like you kind of know what really needs to be done. You may have to create a low spot 10-15 feet away from the house and install an area drain connected to a pipe that you run under the sidewalk and out to the curb if the sidewalk is too high but the curb is low. If you are regarding an entire yard the best way is a small or medium skid-steer loader or bobcat operated by a skilled driver. The skilled part is crucial because fine grading a yard with a piece of machinery is definitely not a job for a novice or even someone with a few hours experience. Trust me on this one, I know from experience that grading a yard with a bobcat and getting it right is very difficult work unless you have done it many times before. A backhoe is best for digging long deep trenches and can also be good at making a swale.

As for the fall, you need to fall a minimum of 1.5 feet or 18" across 75' to ensure proper drainage and that is MINIMUM! 2% is always the minimum for drainage across landscaping. 3-4% is best. 75x.002 (2%) IS 1.5 FEET OR 18". If the sidewalk is too high then take it out and re-pour it at a lower grade when complete with the grading, ramping it down from the neighbors yards.
If you can only slope 4" or .333feet that is .333/75 = .0044% or less than 1% which is essentially flat and will not drain fast enough. Your soil will hold water and likely continue to be a problem.

It is possible that the lowest part of your yard is not low enough, in this case you bought a bad lot and the only real answer that will fix it is to raise the house's slab or to locate a local storm sewer (one in or adjacent to your yard, possibly in the street)that is deeper in the ground that you can tie into. It sounds like the person who graded your site and perhaps the entire neighborhood did a very poor job. Note connecting any pipes to a local storm sewer is also not a novice or do-it-yourself job and requires permitting and approval by the local county or city.

As for a swale, it should be shallow barely noticeable not a deep sharp edged ditch. You want to gently channel the flow of water in a shallow ditch. I'd say 3to 6 feet wide and about 1" deep for every foot of width. So a 3' wide swale is 3" deep in the center. The edges should be rounded so sod or grass will grow in evenly and you can still mow it without it being obvious from a distance that there is even a swale there.

Well Robert, I hope that helps, one last piece of advise is to get a good rain coat and umbrella and go to the house when it rains and watch exactly what is happening. Chances are it is not as bad as you think. Bring some small flags with the wire stakes attached and use them to mark areas with standing pools of water more than 1/4" deep. Also note issues like splashing water and mud, missing gutters, etc. Gutters may also help fix your problem. Good gutters with downspouts attached to 4" corrugated flexible piping will move water away from your house and keep it from splashing on the siding. Also consider installing plants around your foundation with mulch to help break up falling water and limit splash-back. Gravel can help also for this.

You might also like my websites where I write about landscaping:
http://www.seanjmurphy.com
and
http://amenityarchitects.com
http://www.facebook.com/pages/Outdoor-Landscaping-Design/175754405799612

Good Luck
Sean J Murphy, ISA, LA, LEED AP


---------- FOLLOW-UP ----------

QUESTION: Thanks for your response.  But I am not sure the best way to proceed based on your input.  The swale would run next to the property line and I cannot bust up my neighbors sidewalk.  I do not think it is practical to lower the sidewalk.  But I can do a curb cutout and run a French drain and get a 1% slope (at least along the side of the house).  
You are correct this is a bad lot.  This area is really low and it floods a lot.  It was built on a creek.   The house has flooded in the past.  It is in Florida and we get heavy rains and the water table is only a few feet down.  I looked at the local storm sewers in the street and they are not close to my house so I cannot tie into them.   It looks like the developer 30 plus years ago put in drain boxes in some yards that drain to the city storm water drain.  I do not have one, but the neighbor behind me does, but it does not seem to work.  I might be clogged.  I called the city, but they say they do not maintain them.  I could try and talk to the neighbor to see if I can go in with them to fix their drain.  That way I could drain my property towards that box.  
You stated to grade 3-4?below the T1-11.  If I do that and then drop 紨 per foot to a swale.  The swale will be flat with virtually no slope.  If I do the French drain to the curb, should I run the pipe under that swale 10?from the house or should the French drain go next to the house.  Also in order to get that 1% slope I can only run the French drain pipe along the side of the house.   I could put another French drain on the other side, but there are a lot of trees in that part of the yard.  Ideally I wanted to also be able to drain the back yard.  But I cannot do that and maintain a 1% slope.  Somebody mentioned digging down past the hard clay in low spots to allow the water to drain down.  Do you think that could be a solution for the back yard.
I think you response to raise the house is the real answer.  But somehow that sounds like it would cost more than the house itself.

Thanks in advance,
Robert

Answer
sorry Robert without being there I can really tell you what else to do. Sounds like a really bad lot. French drains wont work well at all at 1% slopes, they will hold water at that slop.
Raising the house would likely cost between $10,000 and $20,000 in my experience. You need to see if you can get an local civil engineer or registered landscape architect to come out and give you some consulting advice on your property. It will likely cost about $85-125/hr for this. Or try the City/County and ask if they have an engineer who can assess the situation for your neighborhood. You probably need to tie into the local storm drain system, but that may not be an option. Sometimes there is no easy fix, sorry.