Stop me!

Hello,
I am leading a project that involves creating a useable floor in a barn. Currently the floor is uneven, dusty and dirty and occasionally gets wet during a major rain event. So we have a plan. Please stop me if I'm doing something stupid.
Our plan is to lay down some straw put two loads of fill dirt, some more straw, a load of sand, some more straw, water and then till down through the sand, into the dirt to get a rough mixture that resembles cob. Then use a compactor to pack it in and get it semi level.
This is our stage one. Eventually, we want to put down radiant heating and a proper earthen floor. But in the meantime, we are thinking that this will keep us dry and be much cleaner and be a solid foundation for the earthen floor yet to come.
So, please. Tell me if this will work or if I'm making a big mistake. Thanks.

That sounds like an interesting idea. I mean interesting in that I'm interested to see how it turns out, not interesting as in "interesting". Whatever you decide, please keep us up to date.

The book The Hand Sculpted House (by someone someone, I'm too lazy to google it right now) is a good resource for earthen floor building. If you haven't read it yet, your local library should have it. If they don't, then your local library SHOULD have it and feel free to tell them I said so.

I've never done like this before, but I could see a couple of challenges that might come up - based on my reading.

First, tilling straw can be a challenge as it wraps around the tines something fierce. Perhaps a solution would be to toss it through a chipper first? But then would it still give the structural somethingsomethingIreallyneedmorecoffee you want for a floor? Question for more experienced people.

Is a cob-like base likely to give you the best result for the work involved? It may. Like I said, I've not done this myself. However, from my reading it looks like cob-like mixes wick water really well, that's why cob walls need such a big foundation and overhanging roof. Moisture reduces the strength of cob (again going from reading). The ground (at least around here) has lots of moisture in it some times of the year. But then again my worries may be moot, and it could be well worth a try.

Hoping more people will weigh in on this question. In the meantime, if you haven't yet, check out the book I mentioned above. They have some lovely write up on earthen floor construction.

Hi Ben...Welcome

This caught my eye today because of the "Stop me" title...

So yes...STOP!!!

This is not, under just about every circumstance I could think of, other than an extremely arid and very desert like biome a good recipe for the preliminary foundation for any structure, let alone the dias of any "earthen floor" modality...

I would strongly recommend reading a post here called "Raised Earth Foundations." I believe you may find it informative and useful.

My primary concern is the amount of "unknowns" not shared about the architecture this is planned for; its regional location, age of the barn, current foundation type, general condition (photo would really be more than helpful in this case) and other details to be determined. Good advice only can come from a complete picture and outline of goal sets for the project.

Whenever I hear/read....

...occasionally gets wet during a major rain event...

Then I believe there to be a compromise or other mitigating issue with proper drainage. This alone arrest any possibility for a durable earthen floor system until this "wet condition" is dealt with thoroughly and completely, as earth floors exposed to any liquid moisture of this form acts like a sponge and can harbor the moisture for a very long time...This often leads to other issues with mold, and decay.

Sorry, for the depressing view, but I believe you can still (perhaps) achieve your goal, but other information will have to be collected to give proper guidance and the modality of the system greatly modified.

Regards,

j

The project is in North Georgia, There is plenty of rainfall and the surrounding ground certainly gets wet. However, under the barn, it stays quite dry. The exception is when there is a major rain event and water starts to move through the field. We have plans to set up a swale to catch that rainfall and direct it elsewhere.
Here's the barn...

And here's what happens when we camp there...

As you can see, there is no foundation at the moment, just dirt.

Ok J. I've read your post on raised earth foundations about 5 times now and I think I finally get the basic ideas. Please correct me if I am wrong.
1. I could do wooden platform of some kind.
2. A better foundation for our project, if we decide to go with an earthen floor, would be gravel of some kind.

Questions surrounding number 2.
1. What type of gravel would be best?
2. How much?
3. I have read about building up flat spots with packed earth as a foundation. Do you see this as a viable option.
4. What about a combination? Gravel then rammed earth?
5. It looked like the Wariguri Chi-gyo could be constructed without anything holding it in on the sides. Correct?
6. Probably most important question, would there be a better alternative to a cob floor? Looks like tataki would do better with moisture? Limecrete? Hempcrete?


Our immediate goal is to do something that will raise the level of the barn a few inches and be clean and easy to walk on.

I am beginning to gather the importance of keeping cob dry. Our test patch has not indicated any problems yet and it gets wet regularly, but I have heard it enough to believe it.

For a relatively clean floor now,  you could scrape up all loose material and then put a layer of finely crushed rock.

 After the material is laid,  hose it down lightly and tamp. This will wash most fine dust to the lower levels.

Hi Ben,

Loved the last photo...!!!

Isn't it strange how great camping location seem to lead to special delivers some 9 months later...

I love it when folks like you come back with "number list responses" it makes my job of responding fun and easy...Thanks for that...

1. I could do wooden platform of some kind. Our immediate goal is to do something that will raise the level of the barn a few inches and be clean and easy to walk on.

Yep, in a nutshell, that would be the fastest, simplest, and probably (in my experience of working in all these mediums of stone, earth, and wood working modalities) the most inexpensive both fiscally and physically is typically timber and plank...

If you select this one, we can dig into details...Your frame presents as a simple "pole barn" but the bones look solid and the only obvious challenge glaring at me is the roof design (too short of overhangs and a "dumping pitch" on the front) and the second issue..."drainage"...is tied to the first...

2. A better foundation for our project, if we decide to go with an earthen floor, would be gravel of some kind.

A+ again!!!

Questions surrounding number 2.
1. What type of gravel would be best?
2. How much?

The structure will either require a new roof design ($$$ and probably not worth it at this time) or it will need the proper drainage it never got in the first place.

I like traditional "gutters" and these are "under ground." So, a "drip line" drainage trench is the quickest remedy for this. That trench or channel should have a 2% to 5% slope (~1° to 3°) and "run to light." If the distance to "light" (aka where the pipe discharges to open topography) is too far away, a distribution pond/pool of open sump should be dug to accommodate the max flow of the area that distributes water by the roof and drainage area of architecture.

This channel works best with clean 20 mm (~3/4") stone, and if possible lined and covered with filter cloth before final infill with gravel. The top "lift" (layer) of gravel can be of a nicer cosmetic stone or even a thin layer of sand (if the trench is protected by filter cloth and grass species tolerant of fast drainage/sand bedding.

Volume will be determined by length of trench, and in your area the depth starts at 300 mm (~12'). For the floor area of the barn, the lift of gravel should be 200 mm (~8") and plate compacted.

Note: If opting for a "crawl space" and raised wood floor there are a few inexpensive tricks we can go into once that choice is made...

3. I have read about building up flat spots with packed earth as a foundation. Do you see this as a viable option.

Not until the drainage issue is addressed and rectified.

4. What about a combination? Gravel then rammed earth?

Again, no matter what natural architectura modality of construction is selected...ALL...start with solid...and...WELL DRAINED...foundations.

5. It looked like the Wariguri Chi-gyo could be constructed without anything holding it in on the sides. Correct?

It depends on the method selected, the size of the stone, angle of repose in the smaller stone sizes and/or the skill of placing stones of a larger format. These form what is called a "drainage field" or "drainage diaphragm" yet still need to "distribute its load" to a "drainage system that carries the water way in a capacity to match the max load endured by the coverage area of roof.

6. Probably most important question, would there be a better alternative to a cob floor? Looks like tataki would do better with moisture? Limecrete? Hempcrete?

Short answer...yes. Cob floors are labor intensive comparatively. My first choice is almost always wood, then stone/brick, then tataki and related systems.

I am beginning to gather the importance of keeping cob dry. Our test patch has not indicated any problems yet and it gets wet regularly, but I have heard it enough to believe it.

Some cob types are more resistance than others to moisture...none are very tolerant cover type without continued maintenance and upkeep, especially when exposed to liquid moisture or precipitant.

Not sure how you feel about this, but a better plan may be earthcrete.

All you do is take bags of Portland cement and spread evenly around your floor, then take a rotartiller and mix the existing soil with the cement. Then you have the option of watering it so it eventually hardens, or just waiting for the next rain storm. Either way, it will harden!