WOFATI on bedrock

So the land I am looking into is in an area with rich fertile earth, for about two feet then solid bedrock. Suggestions for 'importing' earth for an earth berm around the building. I suppose a couple dumptrucks of clay soil and I could make a berm around the building. I don't think I will have a true wofati but do want to have an area for a root cellar/storm shelter that is also part of the home. Since digging one seems out of the option, creating a solid earth berm around and above part of the foundation is my best idea so far.

Gail Jardin wrote:So the land I am looking into is in an area with rich fertile earth, for about two feet then solid bedrock. Suggestions for 'importing' earth for an earth berm around the building. I suppose a couple dumptrucks of clay soil and I could make a berm around the building. I don't think I will have a true wofati but do want to have an area for a root cellar/storm shelter that is also part of the home. Since digging one seems out of the option, creating a solid earth berm around and above part of the foundation is my best idea so far.

I think I am going in a different direction now, but I have given WOFATI's a lot of thought, and I think the situation you are in (as my site location would be as well) with a WOFATI on bedrock being not just possible, but IDEAL!

IDEAL!

First of all, you know the building is not going to sink, I mean it is sitting upon bedrock. But better yet, ledge rock is always warm, like always 57 degrees, so there is heat in that. It is much easier to heat a building from 57 degrees to 70 degrees when it is -20 degrees below zero (f) outside then to take a home from -20 degrees (f) outside to 70 degrees. It is called "degree days", and ultimately a person on bedrock is using geothermal heat without having to dig down an extra 4 feet to find it. That is a very, very sweet deal.

But water runs over bedrock, but that is okay. I would scrape the soil off the bedrock, and then to make a flat concrete slab, I would then bring in crushed rock and shim the area level to sit my Wofati floor upon. Any water that accumulated between the concrete slab of the WOFATI, and the bedrock, would drain right through, while still allowing the slab to get that all important geothermal heat.

Myself, I would dispense with passive solar, and instead super-insulate the WOFATI which I think would allow for a more comfortable home, and then pipe active solar heat through the slab. A small boiler heating the slab would also work. Again, it is not going to take many BTU's...

As for the earth berming, I think you have more soil there than you think. I live on very thin soil too, but it comes in pockets, and scraping together enough soil to make a berm is really not going to use a lot of soil. As for moving it, you have a few choices. There is something to be said for renting a skid steer for a day and moving all the earth you need in a day for $450, but moving a little earth at a time, every day means a lot of earth can be moved too. I moved hundreds of cubic yards last summer doing so, only moving 1 cubic yard at a time. At the end of the summer I had moved over 700 cubic yards of gravel from a gravel pit a 1/4 mile away.

Even with a wheel barrow that is 1/4 cubic yard, hey (4) wheel barrows is 1 cubic yard. If a person was to move eight wheelbarrow loads per day, in a weeks time they would have moved an entire dump truck load's worth. Even if they moved only (4) wheelbarrow loads per day, in two weeks time they still would have moved an entire truck load of earth!

I have known people that have saved for weeks and weeks and weeks to get enough money to buy a dump truck load of earth, when they would have spent $0, and had the same amount of earth, had they only moved a few wheelbarrow loads per day.

In any case, moving that much soil that slowly, you would not have to worry about slumping; you would be compacting it as you went.

Why would digging one be out of the question? You can rent or hire an excavator with a breaker attachment. Think a jackhammer mounted where the bucket normally is. If your bedrock is fairly soft (Shale, slate, limestone, sandstone ect) it would make short work of it. Granite would be another story, but it's worth looking into. Might be cheaper than trucking in material.

B. Rey. wrote:Why would digging one be out of the question? You can rent or hire an excavator with a breaker attachment. Think a jackhammer mounted where the bucket normally is. If your bedrock is fairly soft (Shale, slate, limestone, sandstone ect) it would make short work of it. Granite would be another story, but it's worth looking into. Might be cheaper than trucking in material.

Because bedrock impedes water so it would end up being a swimming pool.

I think that you could have two bermed structures one for a root cellar and another for the house.
I would berm on 3 sides and have the un-bermed entrance to the cabin facing uphill, and have a berm/ditch/drain divert the water before it hits the the structure.

I want to second the idea of 6mil radon and water barrier, rigid foam insulation R-40, and cement thermal mass with PEX pipe for radiant floor heating.
You can then heat the 100F (38C) water in the pipe with a solar collector or wood/pellet or heat pump.
A simply wind unit AC can cool the whole building down if you every need it, and bring humidity under control.
A ERV can be used to vent the bathroom and also provide enough air exchange for the entire house.

Travis Johnson wrote:

Because bedrock impedes water so it would end up being a swimming pool.

Yes it does, so with some good planning on the drainage you can have it fill a cistern naturally with rain water that's filtered through the gravel surrounding the home. Take that problem and make it work for you.

B. Rey. wrote:

Travis Johnson wrote:

Because bedrock impedes water so it would end up being a swimming pool.

Yes it does, so with some good planning on the drainage you can have it fill a cistern naturally with rain water that's filtered through the gravel surrounding the home. Take that problem and make it work for you.

That is true...

I would think it would be less costly though to scrape off the topsoil and get the site down to bedrock, then shim the site level with crushed rock. I could do all that with my farm tractor and not have to worry about renting an expensive piece of heavy equipment. Then water would naturally drain, not to mention radon gas being pushed out, if that is an issue.