Getting floor polyethylene around the posts.

One area that others and I have struggled with when looking at earthberm, Wofati, Mike Oehler and any pole/polyethylene floor structures is understanding how to wrap the floor polyethylene such that it keeps moisture out, but allows the wooden posts to sink 2 feet below the surface. Especially when dealing with an earth-carpet floor. For many of the Wofati structures the floor is wood, but how did Oehler do it when he made it directly on the earth? How did he keep water from coming up the posts, especially if you were in a wetter area than where he lived? Reading through His books and watching his DVD's I do not see this covered in detail except to "wrap around it." But how would that be possible if you have a post right in the middle of the floor away from any adjacent walls?

Any experienced builders in this area, please feel free to enlighten me as to how you did it, or maybe I missed something really simple. Either way I feel that this is an important area to discuss because when I talked to a traditional builder about these types of structures this one one of the issues that they brought up. Suffice to say, they stumped me. And it is a point that many people get hung up on due to the idea that "wood in the dirt always rots". This would certainly help any other curious builders who have concerns about grey areas like these. Any input is much appreciated. Thanks.

Poly tape.  The red stuff.  Used in conventional building for vapor barrier under concrete. Patch holes, seam sheets together, wrap posts, transition between floor and walls, etc.

How about a small cement, metal or rock pier that goes underground and gives vertical support.  Also have it keyed into the post so that it gives lateral support.  

Seems like it wouldn't be that bad to have a compromise like that given the awesomeness of the rest of the structure.

Mike wrapped his posts in several layers of trash bags and then put the floor poly around the posts.

Trace Oswald wrote:Mike wrapped his posts in several layers of trash bags and then put the floor poly around the posts.

Here is a drawing of what I am seeing in my mind. The last one is the one with the trashbag. Even though that keeps the post dry, that does not prevent water from rising through the holes in the poly sheet where the post goes through. I live in a wet area, where the water table sometimes rises. Even if one were to use metal coats for the posts that does not stop the puncture in the sheet.

Mike Oehler Himself wrote:The polyethylene is a moisture barrier, an absolute one, but it can remain so only if it is not pierced, torn or punctured.

R Scott wrote:Poly tape.  The red stuff.  Used in conventional building for vapor barrier under concrete. Patch holes, seam sheets together, wrap posts, transition between floor and walls, etc.

This is the only thing I could see working. Sealing the plastic to the poly sheets that it penetrates to sink 2 feet into the earth. Taping it, painting it, and sealing it in any way possible, however this would require that you wrap the posts in something much more sturdy than trash bags, seeing as that would not seal well to 6 mil sheets. Does anyone have experience with this idea? Or descriptions of the process? even pictures?

Here's an idea to prevent moisture around posts. I have not done this nor seen it, but, seems logical to me.
I personally did not use any poly around post at all. I added to the dirt around the posts: wood ash, borax & diatomaceous earth to discourage microbes.
Time will tell if I made a foolish or wise decision.

Joshua Plymouth wrote:

R Scott wrote:Poly tape.  The red stuff.  Used in conventional building for vapor barrier under concrete. Patch holes, seam sheets together, wrap posts, transition between floor and walls, etc.

This is the only thing I could see working. Sealing the plastic to the poly sheets that it penetrates to sink 2 feet into the earth. Taping it, painting it, and sealing it in any way possible, however this would require that you wrap the posts in something much more sturdy than trash bags, seeing as that would not seal well to 6 mil sheets. Does anyone have experience with this idea? Or descriptions of the process? even pictures?

Or, you could use the tape to wrap the poly sheet tightly to the post, sealing the "hole" there. Any breaks in the sheet running out from the post, you seal with the tape. Done.