"Fixing" Cat's Root Cellar:

My Plan

My helpful resources (in print) are: 

  1. Root Cellaring, by Mike and Nancy Bubel

  2. Peak Oil Survival by Aric McBay

  3. Mother Earth News by Steve Maxwell

The root cellar needs several improvements, to make it more functional and to keep the air fresh:

  1. Electrical:  Provide electrical outlet on stud wall, so can add fan if needed.

  2. Ventilation:  A few years ago, I added a heat vent to the room (on stud wall), to make it a drier storage space.  But if I intend to use this as a root cellar, I will need to remove or close off this vent.  I've decided to build a box around the vent, with a removable cover; close the vent and cover with removable insulation (behind the removable cover).  Then, if I add some kind of heat exchange to the furnace, I can open the vent to utilize the air conditioning.

  3. Replace ventilation with two 4" aluminum dryer vent pipes through the west exterior wall, next to the window (or one on east, one on west side).   Direct one to the floor via an elbow, to bring cool outside air into the room.  The other opens near the ceiling, so warm air can exit.  Photo, right, shows joist space where pipes will exit.
  4. Per Keith H., if exit vent pipes on opposite ends of the house, prevailing or stronger winds may end up driving air flow, rather than the convection caused by cold air sinking and warm air rising inside the cellar.  Air pressure on the windward side should be higher than the lee side; but if air is calm 90% of the time, this may not be an issue.

  5. On the outside, extend warm air vent vertically at least 8 feet to optimize the chimney effect.  provide flapper-vents on both pipes, to control air flow, and screens, to keep insects and rodents from entering the pipes.  If use 4" pipe, wide-mouth canning lids and coat-hanger wire make good flappers.

  6. Jeffrey F. prefers 6" PVC to optimize air flow; less than that, air friction could be a problem.  However, Keith H. used 4" pipe and found he didn't need any dampers. 6" PVC is problematic for my root cellar because it requires too big a hole through the exterior wall - not enough room in joist space.

  7. My contractor suggests using 4" aluminum dryer-vent pipe instead of PVC (PVC will degrade in sunlight).

  8. Dampers (from Jeffrey F): In theory, a single damper (on one of the pipes) would suffice.  But using two gives more options, since each is unlikely to offer a perfect seal.  And actually, you don't want a perfect seal, as the cellar needs some ventilation to stay fresh.

  9. The only time they need to be closed is when the weather is so cold outside (zero or below) that the cellar is in danger of freezing, and the cellar temperature is about 35 degrees.  In the summer, the cold air in the cellar will be more dense than outdoor air, and will tend to stay put; but since there is no change of cool air from outdoors to cool the cellar, it probably makes sense to close the vents, at least partially.

  10. Jeffrey used 6" PVC and made his own dampers (he didn't provide details).  You might try modifying a regular 6" stovepipe damper.  They are not intended to make a seal, but only dampen flow, allowing some air to pass through the holes in the damper.  You could glue a piece of plastic on the iron disc, to cover the holes and make a better seal.

  11. If use 4" pipe, wide-mouth jar lids work great. 

  12. Insulation:  Insulate interior stud wall and ceiling, and cover with 4 - 6 mil plastic sheet as a vapor barrier.  Also decided to insulate exterior walls above ground level and extend 6 - 12" below ground level.  If moisture becomes a problem, can add wallboard (type used in bathrooms)

  13. Insulate door with blue insulation board; add vapor barrier.  Install weather stripping to door jam. 

  14. Add removable Plexiglas storm window on outside of window.

  15. About 3 feet of the concrete north and east wall is above ground.  If needed, bring in soil to build up berm covering more of that wall with earth, or insulate wall on inside (behind shelves).  May not be needed because these walls are on cool side of house, and also shaded by big fir tree.

  16. Humidity control:  If room is too humid, add vapor barrier on inside of concrete walls.  If too dry, dampen floor (or set out containers of water) as needed, during seasons when not enough moist air can enter (dry summer, or frigid dry winter weather).

  17. The shelves are painted pine board.  Should they be replaced with something less likely to rot? If so, what?

Go to Sketches to see floor plan and cross-section sketches (not to scale)


Menu to my Root Cellar pages:

  1. The old root cellar

  2. The plan <===You are here

  3. Sketches

  4. Track progress:

  5. Mostly cleared out

  6. Blue wall, ceiling & door insulation

  7. Ventilation