[youtube http://www.youtube.com/watch?v=q_KwwLOg_WI&w=420&h=315]
There are a lot of little details you can search on the Internet. This is just a basic introductory video to show you the cordwood/earthbag concept. What I like to do is have the mortar recessed slightly. It looks a little better if the wood is protruding slightly. You smooth this out. The mix is very similar — it’s basically cob. You could also call it earthen mortar.
Here is my general impression of cordwood construction. It’s extremely beautiful. It’s very practical in certain areas where you have an abundant wood supply. But it’s very labor intensive. Earthbag is several times faster. So it’s very slow. What I would recommend for most people is maybe just use it around a doorway, an entryway, because it’s very beautiful. Maybe around your fireplace, something like this, because it’s very beautiful. You can search the Internet and see some really beautiful examples of cordwood construction.
You can watch almost 100 videos at Earthbag Natural Houses YouTube channel. Each step of instruction, including how to make gravel bag foundations, is shown in detail.
Earthbag Instructable: steo-by-step earthbag building instructions
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.
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!!
Yes, cobwood is what some call this method. Good point about not needing insulation in hot hot climates.
To speed construction I didn’t use mortar below the first course. There’s limited time. I mostly wanted to show how to use cordwood/cobwood on an earthbag foundation.
I love it!! so glad to see it here!!
This calls for a more thorough blog post in the future.
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:)
Using lime or cement mortar on the outside and cob on the inside is a good solution.
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.
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
technique.
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.