Question
QUESTION: I would like to install a paver patio in my backyard. The back yard which is 16x30 has a negative slope. I live in a row house in Washington DC on Capitol Hill. One contractor has advised me that even with re-grading if there is no drain in my backyard,I should only pave half about 240 square feet to leave room for water to drain in the soil.

Other contractors have said it is no problem to pave the whole thing. The negative slope is already causing water problems in the floor in my kitchen. I don't have basement. The slope is steep...about 2 percent higher in back than front. How can I determine whether it safe to pave the whole thing. No one has suggested french drain. One contractor say he can run pipers under the pavers to allow water to drain underground into the alley behind my house. Also if I re-grade my backyard the area just behind fence belongs to the city so it will remain higher than my yard.  How can determine whether is safe to pave the whole thing?

ANSWER: Hi Terry

Ok, any space can be paved regardless of its dimensions, however it clearly must have a drainage network that is capable of removing water.

I would consider using a french drain (plastic tube placed in a trench filled with gravel) around the whole outside and running parallel french drains across the slope that lead the water into the main external drain. These gravel areas could then planted with plants like Iris or sedum acre to render them beautiful.

Thanks for any ratings that you give for this answer in advance

Jonathan

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

QUESTION: Thank you for your quick response. What do you mean by main external drain...are you thinking if a drain that is tied into the city's water system or is that something that would built by the landscaper?  Also, if it is the former...it may not exist.

Also, my question is how do determine what kind of system is necessary. Or if it is okay to take the advice of the contractors who say it is not. ... I am trying to decide which contractor's advice to take. Do I need a some kind of surveyor or landscape engineer?..no contactor has suggested using a french drain...I even asked and was told that would not work...not sure why. Again thank you for advice and I will ask again about the french drain.

Answer
I simply intended a main drain (tube in a gravel trench) that that runs around the entire area and can act as a main point of drainage - where all others could lead.

French drain systems work anywhere where there is a slope and a place to drain the water to. maybe a pond, a reserve tank (rainwater tank) or just a run off (a pit filled with rocks)

I would clearly have to see the property and there is a limit as to how much I can help you on here but my advice is to stick with the simple solution and that's a french drain!

Jonathan