Building a Root Cellar

Even though we made every attempt to keep it dry and installed overhead electrical lighting (a single bulb), it was still a dark and moist place, and consequently a breeding ground for some of the largest and ugliest spiders I have ever seen.

We lived in Maryland at the time where the soil was mostly clay. Consequently it was easy digging. So easy as a matter of fact that we wound up digging a 10 foot wide, by 12 foot long, by 9 foot deep root cellar, and capping it with a shed that we placed over it. The shed had a trap door that allowed us access to the root cellar.

After digging the hole for the root cellar, and before placing the shed over it, we framed and lined the root cellar walls with pressure treated 2×4 walls sheathed with marine plywood. We also added cross bracing to prevent any threat of cave ins. Finally, we poured a concrete floor to create a clean and level surface. We also included a small well depression in one corner of the root cellar for a sump pump, which we wound up needing more times than I can remember. After building the root cellar and sliding the shed over it, we installed a couple of 3” diameter PVC pipes in the root cellar that vented to the outside of the shed to allow the root cellar to breathe.

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We also included a valve seal mechanism over the ends of the vent pipes to enable us to seal them off during very cold weather and to prevent freezing temperatures in the root cellar.

Finally, we installed shelving in the root cellar. In fact, we wound up lining all of the root cellar walls with shelving from floor to ceiling, and I must say we did a good job of keeping those shelves well stocked.

Building a Root Cellar Today

When building a root cellar today you don’t have to go to the same level that my father and I did. As a matter of fact, you can build a root cellar in your own basement. Simply find the coolest and moistest area in the basement and close it off with some 2×4 framed walls. Make sure you include an opening for a door.

Then insulate the walls with rigid foam insulation and sheath both sides of the walls with a moisture resistant drywall. Also insulate the root cellar ceiling and sheath it with moisture resistant drywall. Make sure to tape and mud all of the drywall seams to create a tight seal in the root cellar. It is important to note that the outside basement walls associated with the root cellar be at least 2/3rds high backfilled with soil.

The backfilled basement walls help to ensure cool temperatures in the root cellar during the warmer months.

Next, add some outdoor ventilation to the root cellar to ensure it maintains a cool temperature, but not frosty temperature. Include valves on the ventilation pipes to close off the root cellar to the outside elements when the temperature drops below freezing. One ventilation pipe should be located about a foot off the basement / root cellar floor and the other about a foot below the root cellar ceiling.

Again, make sure the crawl space is vented and that you can open and close the venting depending upon outside air temperature conditions.