Lemme see now, I can "grab" PVC or iron with my hands but mother nature can't? Don't make sense to me!
Royce, where is SB? We don't have much of a frost problem here in southern Florida either. Have Fun Michael ----- Original Message ----- From: "Royce Woodbury" <[EMAIL PROTECTED]> To: "Multiple recipients of sslivesteam" <sslivesteam@colegroup.com> Sent: Saturday, January 08, 2005 2:40 PM Subject: Re: depth of post footings and frost, was Re: sslivesteam-Digest - Number 1318 > Hi All. At the risk of enraging those who hold strong convictions on > the matter of frost heave, I would like to throw out some ideas. > 1. I am beginning to understand that what is called "frost heave", is > the process whereby freezing soil at the surface of the ground can only > expand UP as the water freezes. The freezing soil "grabs" the post and > "pulls" it out of WHATEVER is around it below the soil surface. > 2. Repeated freeze/thaw cycles of the surface soil "jacks" the post upward. > 3. The final thaw at the end of the season results in a contraction of > the soil (as the ice melts) which will allow the post to wobble. > 4. There is a belief that if you extend the post below the frost depth, > the unfrozen soil is stable and will grab the post bottom sufficiently > to prevent the surface soil from pulling it upward. This would seem to > imply that the gripping force on the portion of the post below the frost > line is greater than the gripping force on the post at the freeze/thaw > depth. > 5. If all the above is true (and I'm just guessing - correct me if I'm > wrong), then it would seem that frost heave might be prevented by simply > wrapping the upper portion of the post in something slippery (like > polyethylene) which would prevent the surface freezing from gripping the > post. Which may be why someone's (I can't recall whose system it was) > method of using PVC pipe works. The PVC is slippery enough that the ice > can't grab ahold of the pipe. (As well as Gordon Watson's method of > using steel galvanized pipe). > > Just my thoughts. Any comments/criticism welcome. > > royce in SB - where I will NEVER have to deal with frost heave. > >
