Cordwood Construction on Gravel Bag Foundation — 14 Comments

  1. Hi I want to build a cordwood studio (single story) in my garden but am unable to dig foundations as i have a back issue and live alone…does the Earth bag/gravel bag foundation need to be over a deep rubble trench or are they laid directly on sand base/earth base? Here’s hoping! Thank you

    • If your soil really drains well so that there is no danger of uplifting frosts, then you can start laying bags of gravel right on the ground. Otherwise you will need a rubble trench foundation and possibly a French drain embedded in it.

      • Thank you so much for your reply. That area of garden is gravelled over a membrane; do you think that would be well draining enough?

        • If the membrane is moister permeable then you should be fine, or is the layer of gravel is deep enough to ensure that moisture will not wick up into the walls or floor.

  2. Hello Owen, I like your method, I, as you know am doing a cobwood structure right now as my personal home, one thing I am going for in my region (Texas) is thermal mass, here we look for methods to keep the home cool in summer, so we do not focus on the sawdust insulation in between the the cob mortar. The one thing I would like to point out is that I would have laid out a bed of straight cob on top of the earth bags to a depth of about 4-6 inches then started placing cords, this would give a better hold and course for the first run of cords!! Glad to see you are showing this Owen!!

  3. Is it possible to do the outside half of the wall with mortar and the inside with cob? This would use less cement, and add some insulation? I’ve never anyone do that so maybe there is a good reason. It would allow less worry about giant overhangs.

    And could I use pallet wood for this? I know it would look horrible, but I was just wondering.

    I like how earthbags allow me to raise a foundation easily. A circle of earthbags 12 inches above grade filled with scroia/gravel etc…That is just a random comment:)

  4. Some parts of the video got edited out for brevity. I’m showing earthen mortar as a low cost option. This would require large roof overhangs or wrap-around porches to protect against moisture damage. Most people use lime or cement mortar mixed with saw dust to slow the drying and reduce cracking. Or you could use lime or cement mortar on the bottom part of the wall and earthen plaster above. In any case, earthen mortar will require more maintenance.

    Also, I encourage foks to experiment a little to see what they like best. It doesn’t take long to make a little demonstration wall like this and then you’ll be able to make more informed decisions. Over all, this was a fun little experiment and I’m glad I did it. I can see why people enjoy building with cordwood.

  5. Comment from Kelly:
    It is interesting about cordwood, though, that yes it takes longer to
    lay up the walls, but then once you have done that you are done! No
    plaster; no paint; forever. I suspect that ultimately earthbag and
    cordwood building might tie in time. Another cool thing about cordwood
    is that it automatically provides a great balance of insulation and
    thermal mass, which few other methods can do. And it can use all kinds
    of junk wood. I would say that cordwood is my second most favorite

    Owen: Good point about cordwood providing insulation. This is particularly beneficial in the north woods where cordwood is most popular. Another point is cordwood takes less physical exertion. It’s much less strenuous than tamping earthbags. It’s more like a bird daubing mud on its nest. Cordwood construction is also efficient because only short pieces of wood are needed.

    • Kelly, I am glad you brought up the benefits of cord wood. I was curious about the comment saying it is easier. And, I guess it is where you live, up in Latitude 48 it seems like the best option. Also, Kelly you mention it being your 2nd favorite building method. What is your 1st?

      • I’m pretty sure he would say earthbag is his favorite. That’s what he’s used on his house, carraige house (garage/shop/office) and guest house.

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