Armchair Builder

Checklist: Keep Moisture Out of Your Finished Basement

Photo by Chris&Riannon

Photo by Chris&Riannon

If we are going to put time, effort and money into finishing our basement, we need to make sure we take steps to keep the moisture out.  There is nothing worse than having to remove new carpet, drywall, and insulation because water made its way into your home.  Here is a checklist I use whenever one of my customers is thinking of adding finished space to their basement.  Don’t forget to speak to your homeowner’s insurance agent to add coverage for your newly finished project.  Most policy’s require a rider to cover basement water damage or damage from a sewer backup.  I have provided two different checklists, one for incorporating a finished basement into a newly built home from the ground up and then one that is being added to an existing home.

If we are finishing the basement as we build a new home from the ground up…

  • Include plastic/visqueen under the basement floor to help keep moisture out.  The sheets of plastic should be taped together with no gaps or holes.  This will also be a part of your radon mitigation system.
  • Install interior and exterior draintile connected with bleeders through the footer every 8′.  This comes in handy if there is ever a problem with either the interior or exterior system.  We are basically adding redundancy.
  • For a large basement, run a diagonal draintile under the floor connected to the sump crock.  This helps when you have a high water table.
  • Apply waterproofing to the exterior foundation wall.  This should be a pliable material that will span any cracks that occur in the foundation wall.
  • Install an insulation/drain board on the exterior foundation wall.  This material actually serves two functions;  It prevents groundwater from being trapped up against the wall, which will eventually make it’s way through.  It also provides an R-Value to a concrete wall that alone, has almost no insulation value.
  • Properly slope the grade around the basement.  The grade should drop 6″ for the first 10′ around the home.
  • Install a high quality sump pump along with a battery backup system and/or alarm
  • Silicone the joints in the concrete floor including the perimeter at the wall.  This is also an integral part of your radon mitigation system.

If you are adding a finished basement to an existing home…

  • Silicone all joints in the concrete floor including the perimeter.
  • Check the finished grade around the basement.  There should be a minimum 6″ of fall for the first 10′ around the home.
  • Make sure all downspouts are connected and discharge rainwater away from the home
  • Check operation of sump pump and check valve.   If the pump is older than four years, replace it.
  • Add battery backup sump pump and/or water alarm

It’s also a good idea to run a dehumidifier in your basement during the summer months to remove the moisture from the air.  This will help keep your new space cozy and dry. Be sure to checkout our new video…Keeping Your Basement Dry.

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