Question

My lawn is lower than the lawns of the homes that surround me. What is the best strategy for keeping water out of my basement?

Asked by Susan Free
York, PA

I have a medium-sized yard that is overwrought with broadleaf weeds. I do not chemically treat the lawn because I have pets. Also, the soil is very hard and needs aeration (I get a lot of water from rain in the one quadrant, and there's nowhere for it to go because my lawn is lower than the three homes' lawns that surround me). As well, I have a flowerbed right against the house on the one side, which is level with a basement window. Should I get rid of the flowerbed and maybe cement the area instead? I sometimes get water in my basement, so I want the foundation to be protected. What is the best eco-friendly way to attack these challenges?

Answer

Elizabeth DiSalvo

Answered by Elizabeth DiSalvo

Norwalk, CT

Trillium Architects

June 27, 2012

Hi Susan,

I am an architect and not a landscape designer but I have worked with this sort of challenge on a number of jobs and at my own home as well.

I am guessing hat some landscapers might want to chime in with more specifics on plants but in general this is what I would do (and have done!) .

Keeping water away from the house

First, the foundation wall of the house. I have often thought about putting a concrete apron around my foundation.

  • My Italian grandmother in the Bronx had this and set her tomato plants in pots on top of the apron and everything was neat and clean and dry.
  • But I am reluctant to do that because it feels less natural and I try to have as little hardscape as possible due to water run off and heat island effect issues.

So what I recommend is a process that many of us in the green building world have used. It involves digging up the ground in front of the foundation wall -- perhaps a 5'-8' swath along the entire length.

  • Dig down a good 18".
  • Then pack the earth in a slope away from the house (Make sure you pack this earth firmly and that the slope is significant enough for water run off - maybe an inch per foot- and make sure it is consistent so no pooling occurs.)
  • On top of that put a rubber sheet. You can get this from roofing supply stores or on line. Basically you want a thick sheet (1/16" or 3/32") of rubber to lay over the entire swath - from foundation wall to outer edge. This will drain water away from the house. You can 'glue' the rubber sheet to the foundation wall with an adhesive that the rubber manufacturer will recommend.
  • Ideally you also flash the top of this rubber sheet but that is harder to do if you are doing this yourself and I find that the adhesive works very well.
  • Put rigid foam board insulation on top of this slope (2" is a good thickness).
  • On top of the foam board put a light gravel and then top with soil. The entire assembly will be hidden under the 'lawn' and only you will know it is there.

This is a simple - yet labor intensive- way to keep water away from the house AND provide a nice added benefit of insulation for your basement or slab. 

The wet quadrant of the lawn

The best thing to do with an area that is always wet is to acknowledge that instead of trying to keep it dry, celebrate the water instead.

At this location I would make a rain garden. A simple way to make a rain garden in an area like yours is to dig a 6-8" depression in that area that gets wet naturally.

  • Leave the native soil below undisturbed but cover/ fill the depression with a loose mixture of sand, organic matter and topsoil that will easily drain and let water percolate.
  • This area serves as a holding area which will let the water slowly percolate into the surrounding soil and not pool on top.
  • In this area, plant a nice garden of native shrubs and other hardy year round plants that are happy in wet areas.
  • On top of all of this put a few inches of wood mulch.

Now, instead of a puddle you have a lovely focal point that helps manage the extra water.

Consider native grasses

For your lawn in general you might consider planting native grasses, wild flowers or ground cover which will keep the weeds away.

Ask your local nursery or landscape expert for recommendations.

These three moves will go a long way toward creating a truly beautiful, dry and natural environment for you and your pets to enjoy!

 

For more information:

Read "I need advice about creating a bioswale or rain garden in my yard where overflow rainwater collects." a Q&A answered by Richard Heller.

Also, check Ryan Flegal's Q&A "How can I improve my outdoor area to avoid getting water in my basement and near-flooding in my backyard?"

Tagged In: basement moisture

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