Impervious surface challenge in Durham (house, landscaping, neighborhood)

[bullbeemer]

I want to build a small screened in porch to my house but just found out I only had 90 sq of impervious surface. Durham Co has a really strict rule on this and I am wondering if there are others who have been able to work around this. I really want to sit outside and not fight the mosquitoes or sun. I had thought about tearing up my long walk way to my front door and doing something more pervious to see if i could reclaim some space to build the porch. But that just seems to be very expensive. Has anyone ever had success in getting an exemption?

[T|K]

I assume you are looking at a concrete porch? There is pervious concrete you can use that will pass.

[carolinadawg2]

Originally Posted by T|K

I assume you are looking at a concrete porch? There is pervious concrete you can use that will pass.

OP said: "I want to build a small screened in porch..."

I think that would require an impervious roof in order to pass.

[StAndroid]

I know this is going to sound trite, but have you called the relevant City of Durham department to talk with them about alternatives? I'm sure they get these questions all the time and can probably tell you the conditions likely for an exemption and what others have done in these cases...

[right_triangle]

I agree with StAndroid. See if you can agree to adding bushes or landscaping to properly absorb the displaced water.

Also, if you're in a neighborhood, pull up the plot maps of your neighbors. See if any have excessive impervious surface allocated and offer to buy it from them. This may seem silly, but it happened a few times in my old neighborhood in Durham.
Unfortunately, it may require both lots to be resurveyed... probably gets expensive.

[Sherifftruman]

I doubt Durham will allow landscape plantings to offset impervious surface. You might be able to do some sort of capture system so that all the water from your porch (and you could add your existing downspouts as a negotiation point) is sent though some sort of nitrogen removal system. Either a large tank underground or through large artesian wells or something. But even then, I'm not sure it would be allowable or easy as Durham is older strict rules due to Jordan lake. You probably need to talk to a civil engineer who specializes in Stormwater treatment.

[BullCity75]

I'm in the same boat. I talked to somebody in the storm water office and he felt confident I could work something out. Didn't really get into specifics though. I think you have to put in for the permit and see what happens. I decided I didn't really want the porch that bad. My "as built" is already 500 sq ft over the limit so I'm letting sleeping dogs lie.

I have a neighbor who built an addition. They were also initially flagged for impervious surfaces, but were able to work something out. I'm not sure what.

[HTY483]

It never hurts to just ask the city engineer. You'll still need a structural evaluation to get your permit though.