Possible foundation decay

I am hoping to build my first/last home at the end of May. I have already jumped through a lot of legal hoops and now I am at my last hoop before building. Here is the problem. My lot is a 'flag lot', our township requires a 50' setback from each line. At a 50' set back, our house would be sitting in a swale which leads to a natural spring/marshy area. (At a 27' set back there would not be any problem.) I am having to put together a presentation to present to the township variance/zoning board on Tuesday, May 9. Does anyone have any expert advise on what the swale will do to my foundation. I have to prove to them that my foundation would be damaged if I build in the swale. Thank you for any help!

 

In situations like yours I have found it advisable to use a reinforced concrete pipe under the house. It should be designed to withstand the footing loads of your house and have an adequate headwall and discharge area to accomodate the expected maximum flow from the swale. A local civil engineer can do this easily.<br><br>I know this is an expensive solution so you also might consider regrading the building area to divert the swale around the house.

 

[Ron]

You do not say how deep or wide the swale is...that would make a difference.&nbsp;&nbsp;In general, the foundation in your area must be at a depth that would preclude frost heave.&nbsp;&nbsp;The swale might have to be filled in order to achieve this, thus creating a change in the site drainage characteristics.&nbsp;&nbsp;If the swale is not filled, you will have water running by your foundation and the potential to erode the overlying soils, thus exposing the foundation is greater.&nbsp;&nbsp;This, obviously, is not a good thing!&nbsp;&nbsp;Agree with &quot;darct&quot; that subsurface drainage could be done, but that would be expensive.&nbsp;&nbsp;Filling and re-routing the swale around the structure by re-grading would be the most practical solution if you can't get a variance.&nbsp;&nbsp;Be sure the fill extends significantly beyond the structure so that you don't run into steep slopes and erosion issues created by the fill.

 

[JC]

If this swale is a natural drainage feature of your neighborhood, you could have BIG problems trying to rerout or backfill it.&nbsp;&nbsp;There could be lawsuits from the city and your neighbors if the natural drainage is altered to an extent that damage occurs to other property.&nbsp;&nbsp;If you really like the lot, I would use the Frank Lloyd Wright approach to solving this problem.&nbsp;&nbsp;Have your architect rework the floor plan such that the house cantilevers over the swale or bridges in some acceptable fashion.&nbsp;&nbsp;Good luck!

 

[JAE]

I generally agree with the above comments.&nbsp;&nbsp;One additional point:<br><br>Your main thrust seem to be to convince the governing authority to allow you the smaller setback, thus allowing construction on an appropriate location on the property which avoids all of the pitfalls listed above.&nbsp;&nbsp;This is the KISS (keep it simple stupid) solution.&nbsp;&nbsp;Also the most practical and economic solution as well.&nbsp;&nbsp;To help convince the authority that a building shouldn't/couldn't be positioned over the swale, a geotechnical engineer can certainly help provide you with a letter report outlining the issues and concerns regarding drainage re-routing, foundation settling, etc.<br><br>