I'm curious about dirt floors and how they hold up and hold heat in a cold climate.
1) If there is good heat in a room that has a hardwood floor built over hard-packed soil, but is not insulated, will the floor be like ice in a northern winter like it is for a cement floor? The heat is coming through the ducts in the ceilling of the room.
I'm curious as to whether such a space could be used for movement classes with bare feet or lying on the floor in the winter. I'm also curious in a similar vein, if a yurt were on a raised floor over packed earth rather than on a platform.
2) Are there any issues that I should be aware of? It seems to be mold free and dry, but I'm not sure about insect/bug issues, etc.
Please share if you are experienced with this type of floor.
Was the dirt floor mold free and dry during all seasons of the year? If not (and even if it is) you might be better off putting in a moisture barrier, like a plastic sheet, between the dirt and wood floor. You also might be better off using a thermal break, like Styrofoam, between layers. You don't want heat loss or cold penetration if you can help it.
Here in N. Ohio I've seen the ground rise 5 inches from freezing during winters. That's why you need sufficient footers. What you want to do may well work. But if it doesn't you may have to start over with your building or floor. It may cost more to do it right the first time, but it will be cheaper in the long run. I had a building in our museum that I built too close to the ground (the dirt was very dry in summer). The wood floor rotted out in thee years. I had to jack the building up to raise it, put in plastic and gravel and build a new floor. Lots of avoidable work if I had done it right the first time. The first settlers in our area used to clear an area, stomp it down and build a fire on it to harden the dirt. They then build a cabin on it. It worked, it lasted for a bit. You could sweep it to keep it (sorta) clean. But it didn't last years. It was just what they could do as a temporary solution to an immediate need.
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I had to think this over a bit before I replied and I am glad I did.
I have what you describe although in my case the wood over dirt is softwood instead of hardwood, but a moot point I think. Anyway here is the skinny on it as I have experienced what you are asking in the State of Maine anyway. Mold WILL NOT be an issue as the humidity in the air in the winter is drastically low in a heated house, especially one heated with forced hot air as you describe.
In my house I have two sections of flooring, and one has 2 inch Styrofoam insulation under it and the other section (a mudroom) does not. Being a shoeless house, we remove our shoes whenever inside, and as such I can say that the floor buffered by insulation is cool, but bearable in our harsh winters, but the mudroom is not. That is where our lockers are, and where my 4 daughters, and my wife and I , remove our shoes and store them. It is a VERY quick walk to get into the house I assure you.
Now my dirt is placed over a concrete slab so that may differ, but I don't think so as concrete is just hardened earth after all. I am not advocating concrete, I just feel I would be amiss to not point that out.
As for rodents; I am not sure. Again I have concrete, but a common practice on concrete slab on grade is to put a box and keep the concrete away from any traps around showers so that they can be positioned during installation. In my house this was about 4 feet in from the edge of the concrete and rodents still tunneled under the slab, found the hole and came into the house through that route. Only when I pulled the shower, filled the area around the pipe with concrete did that stop. HOWEVER, with that being said, a homestead with livestock of any kind is going to attract rodents of this type, and I deal with it to this day. They get in. So while I think having a dirt floor would make it really easy for them, counter measures are still in order. With a dirt floor it may not be an issue if you were just more proactive then I am. Here we are sporadic on rodent control, but a better approach would be to get a dog or cat that is rodent-aggressive. With that in place, and maybe a place with no livestock, a dirt floor with wood on top may work.
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