my dirt bag cabin

[Porkbrick]

i have some acres in the mountains of santa cruz. ive been wanting to build a cabin up there for a long time and after clearing, thinning, rebuilding roads, building an outhouse (not totally finished, but functional), and a small pole cabin/kitchen, i finally started on it this spring. it is a 20x25 with a loft, simple pitched roof, and bermed into the hill behind. the whole structure, except the roof, is rammed earthbags. 50lb feed sacks filled with moist soil, laid in courses (like bricks) and then compacted with much sweating and cursing. between each course is a double row of barbed wire, partly for re-enforcement, but mostly to keep the bags from shifting. every four courses (staggered every two courses so the overlap) there are straps holding the bags together vertically. at the corners and near the windows i'm driving re-bar down through the wall every eight courses or so. all the bags come from a local chicken farmer who is only too glad to get rid of them, and all the dirt is from onsite, either from leveling the site or from digging the foundation. speaking of which, the foundation is a rubble trench. that is, it is a trench 24" wide and 18" deep, lined with filter fabric, drainpipe laid in bottom, then filled with drain rock and rubble (mostly the damn rocks i had to dig out of the trench. so heres the site. some of you may recognize the "thunderbox" from previous posts.


looking at the site. it will be squeezed between the rock and the oak/outhouse

looking down from the site

and looking down from the parking area in front of the site.

i borrowed the ASV from work to level and dig into the hill...

looking up the hill...

looking down from above...

...and some dirt.

i've got shed loads of photos, more to come...

 

[MasterBlaster]

That is so frigging cool! Who needs a grid!

 

[tophopper]

Very cool!

 

[pantheraba]

You are gonna be one very busy fellow...great project.

 

[Porkbrick]

next is the foundation. all dug by hand, about a billion rocks. as you might expect this was the toughest part of the build so far, luckily the rocks in the area are soft sandstone and fairly easy to break.

my awesome wife starting the trench...

trimming the back wall...

some of the rocks required more than a digging bar to vanquish

oh yeah, and lots of roots...


...the rock vanquished. BOW BEFORE THE ROTOHAMMER!


this part of the wall curves to give room to the oak. i like oaks, and there are few on this part of the property. i forgot to mention that all the walls bow out slightly. this is for strength, as well as increasing floor space.

 

[Porkbrick]

You are gonna be one very busy fellow...great project.

ive been going since april, every weekend i can make it out there. i figure it will be a two year project to get the roof on and the walls plastered. so far its going well.

 

[Treepreacher51]

 

[MasterBlaster]

Hey, Jesse.

 

[Treepreacher51]

Howdy.

 

[Thor's Hammer]

Awesome thread Jaime, rammed earth is a great construction method.

 

[woodworkingboy]

Jaime, with the rainfall you get in the area, and tucked into the surrounding ground, what is the situation with moisture in the structure? Cool thread, looking forward to developments.

 

[Porkbrick]

moisture is something ive worried about quite a bit. the bermed sections all have a layer of rigid foam and plastic between wall and dirt. that will keep water from infiltrating that way. i also plan to have generous overhangs on the roof, slope the ground slightly away from the walls, and put a short masonry facing on the bottom of the walls all the way around. all that plus the fact that the sandy soil is very well drained should do the trick... i hope.

 

[Adam_P]

Pretty impressive project. What's that other building you have out there with the glass door? That whole spot looks like an awesome place to get away from it all.

 

[Porkbrick]

the other building was started as a sort of screened in porch/camp kitchen, then a friend moved in and insulated/windowed it. so now its a very small cabin with a sink and stove top outside under the tarp.

some more pics...

filling the trench with drain rock and rubble.

first two courses of bags are double bagged and filled with drain rock to prevent moisture wicking up from the ground.the gap in the row is a huge rock, i decided it was better to build around it than try to hack my way through it. you can also see the insulation and plastic against the hill


and that is the completed foundation!

 

[Porkbrick]

the third course is the first course of dirt bags. from here on out its mucho pounding, and many blisters.



this is the door form box. i found a nice 6'x7' glass french door on craigslist. the walls are built up around the box, every three or four courses a bit of two-by is incorporated into the wall. after the wall is up and the header is in place, the form box will be dis-assembled and the door frame fits in and is fixed to the imbedded two-by.

 

[MasterBlaster]

Keep em coming!

 

[Porkbrick]

...and more bags. the shape of the building is becoming more apparent as the pile of dirt shrinks.

 

[Jed]

You're the man Jaime. Cldn't be more jealous of your hard work. Mine's all gone after three o'clock.

 

[vharrison]

Very cool!

 

[vl2007]

Earthbags...cool way to build!


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[MasterBlaster]

That's pretty cool. I guess there's some formula for knowing how much dirt is needed? I bet it's a super solid structure, especially with a bit of reinforcement!

 

[PCTREE]

I have been yearning for years now to build a cabin or a house here on my property but havent had the time or the money to do it yet. Just looking at your pictures makes me want to make a start....

What is the insulating property of those dirt walls?? Certainly lots of thermal mass.

 

[Porkbrick]

a simple volume calculation will give you a pretty good idea Butch. length if wall x height of wall x width of filled bag (about 16"), minus openings for doors and windows. theres almost always free dirt from construction cos if you run out.

more bags. the concrete is piled at the base of the wall to protect the bags from the sun and feet etc.

more craigslist scores. three 30"x60" windows, one either side of the door and one on the east wall.

the forms for the windows have a flair on the inside so i can make a nice round edge on the insides to get more light inside.

 

[Porkbrick]

What is the insulating property of those dirt walls?? Certainly lots of thermal mass.

tons of thermal mass (pun intended). not strictly very high R-values, but the mass i think makes up for that, especially if the building is designed to take passive solar principles into consideration. the cool thing about the bag system is the flexibility it allows as far as what you can fill the bags with. ive seen articles talking about filling the bags with scoria (excellent R-value) or mixing scoria into the dirt. i experimented a bit with the idea of mixing wood chip with a cement binder and filling the bags with that, but that would require a lot of mixing, and i had a lot of dirt that needed a home.

 

[pete mctree]

Fantastic & imaginative project. I'm enjoying watching the progression