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Rammed Earth construction cost (semi DIY)

 
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I'm looking for some rough estimates of how much it would cost me to build a Rammed Earth (RE) house. I would be building the house myself but I would probably need help with it. I don't mean a huge crew charging big bucks, but maybe a couple of laborers and one person who could at least come around when needed to give guidance. Most of the RE portfolios I can find on the internet are geared to the luxury market. Maybe the luxury market customers feel bad about all the co2 their lear jets are producing and try to make up for it with RE homes, hah.

I was thinking around 1500 sqft. 3-4 bedroom. Where do I even start pricing this? Can this be cheaper than stick construction? I'm feeling pretty lost here as like I said, I haven't been able to find much RE geared to the budget market.

-Matt
 
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Matthew Tubman wrote:
I was thinking around 1500 sqft. 3-4 bedroom.
-Matt



If i recall correctly, you're going to be at a similar price to stick framing. For something that size, you're going to want power equipment: a Bobcat to move piles of dirt around, a pneumatic tamper, and the monster air compressor that the tamper needs.

Remember that when rammed earth is a vernacular architecture, 3-4 bedrooms serve 6-10 people. Doing a big house like that by hand, it happens everywhere, but it happens with 12 people, not 1 plus a couple of part-time employees.

Our 21st-c-American appetite for square footage CAN be adapted to traditional architecture. But it requires adaptation. 1-4 people can build a 12-person project... with power equipment.
 
Mike Cantrell
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So as far as prices.

Go download Gernot Minke's book, Building With Earth.

Find out how much the soil gets compressed. I think it's something like 60%.

Decide on the size and shape if your house, so that you can know how much wall you're building.

Calculate the volume of your walls (L x W x H).

Call a landscape supplier or an excavating company and ask the price for clean fill dirt.

Now you know the price of material!

(Doors, windows, roofs, they're all nearly the same as standard construction.)

Find the type of pneumatic tamper that's appropriate for RE work, find a price. Last time I looked, I think it was $600 or so new, but it's been a few years.

Check the spec for the Sustained Cubic Feet per Minute (SCFM) that it needs.

Find the price for a compressor that supplies that SCFM.

Add, say, $500 for the miscellaneous stuff- lumber and fasteners for the forms and scaffolding, oil for the tools, etc.

There ya go!
 
Matthew Tubman
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Mike Cantrell wrote:

Matthew Tubman wrote:
I was thinking around 1500 sqft. 3-4 bedroom.
-Matt



If i recall correctly, you're going to be at a similar price to stick framing. For something that size, you're going to want power equipment: a Bobcat to move piles of dirt around, a pneumatic tamper, and the monster air compressor that the tamper needs.

Remember that when rammed earth is a vernacular architecture, 3-4 bedrooms serve 6-10 people. Doing a big house like that by hand, it happens everywhere, but it happens with 12 people, not 1 plus a couple of part-time employees.

Our 21st-c-American appetite for square footage CAN be adapted to traditional architecture. But it requires adaptation. 1-4 people can build a 12-person project... with power equipment.



Good point. It does seem fairly labor intensive. I was planning on renting the necessary power equipment of course, the tampers, bobcats etc. It seems that assuming you have the right soil the real expense will be labor. I still want to do RE if I can, but I am skeptical if it can be done on a budget.
 
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I did with a hand tamper I got at Harbor Freight on some walls just to see what the worse case labor rate would be. It was back braking work. I could not find any air tapers to rent. I'll probably buy some next time I try it. It takes skill not only in building but designing the mix and getting those nice looking striations. I tried all kinds of mixes, earth oxides, learned I had too much rock and needed mostly sand and clay or different colors. I then did not have a strong enough clay so I tried portland cement, lime, fly ash, that changes the look I was after. I did outdoor and indoor on a house, the outdoor retaining wall fell apart since I did not seal the top right. I got all kinds of varing results some did not even make sense, and learned. It's an acquired skill in time, lots of practice. I don't know how those pro's do it in wet climates but some look great. I did the book cost estimate, did not work out for me, ended up with too much hauling back to the quarry. Logistics is another area, the cops did not like me dumping piles in the street by the curb a big clear lot is a must. The bob cat needs an open space too I did not have. I ended up hand carrying mixes into a house I was finishing a room doing some RE pony walls. What a mess and work.

Its a rehab I have on the market now you can see the pony walls here: http://www.zillow.com/homedetails/1333-Pauline-St-Augusta-KS-67010/1327433_zpid/

Not bad for a first, some like them some don't.
 
Matthew Tubman
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Terry Ruth wrote:I did with a hand tamper I got at Harbor Freight on some walls just to see what the worse case labor rate would be. It was back braking work. I could not find any air tapers to rent. I'll probably buy some next time I try it. It takes skill not only in building but designing the mix and getting those nice looking striations. I tried all kinds of mixes, earth oxides, learned I had too much rock and needed mostly sand and clay or different colors. I then did not have a strong enough clay so I tried portland cement, lime, fly ash, that changes the look I was after. I did outdoor and indoor on a house, the outdoor retaining wall fell apart since I did not seal the top right. I got all kinds of varing results some did not even make sense, and learned. It's an acquired skill in time, lots of practice. I don't know how those pro's do it in wet climates but some look great. I did the book cost estimate, did not work out for me, ended up with too much hauling back to the quarry. Logistics is another area, the cops did not like me dumping piles in the street by the curb a big clear lot is a must. The bob cat needs an open space too I did not have. I ended up hand carrying mixes into a house I was finishing a room doing some RE pony walls. What a mess and work.

Its a rehab I have on the market now you can see the pony walls here: http://www.zillow.com/homedetails/1333-Pauline-St-Augusta-KS-67010/1327433_zpid/

Not bad for a first, some like them some don't.


First of all Terry that house looks very nice, if I could buy that house and stick it on my land for that price I'd send you a check tomorrow!

Secondly you mentioned a book cost estimate- what was that?

I'll be building from scratch on a rural parcel of land so I don't have to worry about some of the issues you faced.

Thanks!
 
Terry Ruth
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Secondly you mentioned a book cost estimate- what was that?



What Mike described by volume/compression ratio is in most books on the subject. I made test blocks but when I went to ram into form work that mix did not work so it through my estimates off. I'd suggest small projects before doing an entire house. I wonder if those pro's use alot of white portland cement to get it to hold together and don't tell anyone. Mine crumbled on the surface and washed away easy with water if the walls need cleaning until I put a siloxane sealer on it. If you hit it with a vacuum it crumble so I put baseboards down. Next time I'd cast in a nailer for those and cabinets, wood work, but the depth will be tricky....In a room like that where there is nothing to pin/brace form work to the ground it is hard. I used big centerblocks, but when I moved the forms I did not get a smooth transition. I ended up blending them not that it looked bad I just don't get how the pros get it so smooth yet. I'll make real strong forms next time. New construction will be easier.

Good luck it is very nice once you get the hang of it.
 
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from reading the errors made by some folks here I tend to think they did not do their home work. There is a reason to pay attention to aggregate sizing.. keeping ratio of the soil 70% sand / aggregate,  20% clay, and 5-10% stabilizer.  On the aggregate  in my area that would be quarry tailing as small as dust and large as 1/4".  There is a reason to keep the moisture content low. It is mixing with the clay and stabilizer portion of the mix.. Most say no more than 10% water to the volume of the entire mix.

I get the impression one should move form / shutter boards as soon as you start the next course of wall. The wall dries fast enough that if you wait you will not get the clean lines that many complain about.  work it gently with a wire brush.  like any concrete you dont have a lot of open time ...  60 minutes and you are not going to get any real blending. The wall is set.  Still it will likely take 30 or more days for the wall to dry cure for the cement.  

Being that I like to see results.. 2 foot by 16 foot shutter boards seems to be appropriate.  Makes for fairly fast lifts.   Several people can be working and not getting in each others way.   2 people could easily be stomping the earth in an 8 foot section.  So one could have a wall raising party.   I have been thinking that most of the backing for the rammed earth many use 2 x 12 to back up the shutters.  I was thinking I joist as one can get them wide and lengths of 18 foot very easily.   Then when done use them as part of the roof structure or for a lean to shed.   Biggest expense is that on many jobs 20 -30% seems to go to waste.  That is a lot of trash.

Found air tampers on Amazon.. $200 or so.  No real reason to go with more expensive models unless you plan to do this commercially.. just keep them oiled and they should easily do a 2000 sq ft home.  Keep them clean and re sell them on Ebay or craigslist.   As to the air compressors a 6 -10 hp model should do so if one goes the harbor freight route. I can be sourced relatively inexpensively and sold when the entire house is done.. Might want to use it for air tools on the build.

Depending upon where you look some say 6 inch some up to 12 inches on a lift.. Have yet to see any comment on compressing the lifts more than 50%    Seems like another error is that people do not seem to understand.. you have to start compressing on the outside near the shuttering.  Once it is compressed it is also compressing towards the center of the wall.    When the wall is to the correct compression you will hear a change in sound as you continue to compress.  Think solid thud.   In 3rd world countries they use poles and their feet to do the tamping.  Figure if they can hear it you should be able to also.
 
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