On Sun, 9 May 2010 13:41:05 -0400, "James"
wrote:

This is one subject that I find impossible to understand. Although the
theory about having a firm foundation to a point just below the frost line
is clear, everywhere I look I see construction of steps and sidewalks that I
know is not built on a foundation or other support rested at a point below
the local frost line.

I live in an area where the frost line is commonly known as two feet, but
has been known to go down to three feet.

My first case in point is sidewalks and walkways. I see many sidewalks
made either of concrete, flagstone, etc that I know for sure have not been
built by first digging two or three down to get below the frost line. I
see walkways made of flagstone placed in mortor, where I know for sure that
the entire structure of the walkway is no more than five or six inches
thick. How do they avoid frost heave ?

They dont. If water can seep underneath and freeze, you got heaving.
When the same number of liquid molecules solidify they need more space
while forming ice (a lattice structure).


I would like to build some steps up a fairly steep slope. This would be
about 14 steps over a span of about 25 feet (I am just estimating here).
I would like to have flagstone steps, set in mortor. If I follow what I
have read in prior posts here, I would have to build 14 separate footings,
all 2 or 3 feet deep , upon which to place each steps. That would be a
**major** project !!

At one time, I thought that the frost heave problem was a consideration in
structures that would carry a lot of weight, such as the foundation for a
home (traditional footings) or a deck post to support a deck. But then I
read that even steps, sidewalks, and walkways must also be built so as to
avoid frost heave.

I must be missing something here, or somehow totally misunderstanding of how
to deal with frost heave in constuction projects such as these discussed.

Can someone please clear this up for me ???

Thanks !!

James


If your steps drain quickly they are more likely to resist heaving.