JB Construction

Converting Old Basements Into Living Space


By Jim Bruce

JB Construction Services, Inc.


As a remodeling contractor, we receive a few calls a year to look at converting unfinished basements into living space.  I live and work in the Portland Oregon area and the great majority of basement conversions occur in older houses, because newer ones are not built with basements, unless they are daylights.  Things to consider in the planning stage are:

  • Is the basement dry?  I mean “really dry”.  Nobody wants moisture problems that can lead to high humidity, rot and mold.  So we ask each homeowner how long they have lived in the house, have they ever had a leak, etc.  Then we carefully inspect the basement and the surrounding yard.  Does the ground slope away from the house?  Are the rain drains in good shape?  Does the foundation have an exterior perimeter drainage tile and what shape is it in?  Are there a lot of trees around the house that could cause the gutters to overflow?  All of these factors and more are considered.  Even if all of the above checks out, we recommend that almost all basements should have an internal perimeter drainage system installed inside the basement and below floor level, with a sump well and pump to catch any water infiltration.  That same system has a plastic fin that protrudes slightly above the floor near the foundation wall and re-directs any wall leakage down into the drain tile under the floor.  Then we frame the interior stud walls inside and away from the plastic fin.  We have found that this “last line of defense” is very effective and protects the homeowner’s  investment.


  • Is there reasonable access to the basement from both inside and outside?    Building codes require a proper stairway from the inside or outside.  Invariably, the homeowner wants unfettered internal access to the basement, and that can cause challenges with the upstairs floor plan.  The basement must also have a secondary exit in the event of a fire or other emergency.  An egress window or outside door can suffice as a secondary exit.  Additionally, each bedroom must have its own egress window or door.


  • Is there enough headroom in the basement?  The code minimum in Portland is 6’8”, but we recommend  a minimum of 7’0” after all finishes are installed.  We will often dig down to achieve this.  Sometimes the existing foundation is not deep enough and we will build one under the existing foundation walls to achieve the desired height.  There is also the furnace and its ductwork to consider.


  • Is there enough light down there?  Much can be done with windows and light tunnels.  Window wells can be turned into small atriums or gardens.


  • Is the old plumbing in good shape?  We encourage our clients to change out the drains and supply lines, especially in older homes.  If they are cast iron or galvanized steel, they will never hold up for the 50 or more years that a basement remodel should last.  The newer materials are much more durable and efficient.  Having to repair a sewer line under the concrete basement floor, after doing that beautiful remodel, can be very disruptive and costly.


These are the main points that you should consider when planning to remodel your basement.

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