On Sep 16, 8:44 pm, jJim McLaughlin
I did that. I got a lot of redundant posts regarding heaving, but
nothing like a table of frost lines by city. Thanks a lot, Jim. At
least try not to assume that you're the Google guru and no one else is
capable of doing some basic research. I'll wait for a more helpful
response. I won't assume you're the best this group has to offer.
The local building permit/inspection office in each city will know the
depth, based on how far down they require footings to be. Local ag
extension office will probably know, too. NOAA web site has a map, but it
covers whole country, so minor variations are probably not accounted for.
Thank you. I'm not a contractor, I don't know the lingo. I'm just a
feller considering digging some post holes for a small deck,
(precisely why I came to this group looking for help). My queries
didn't include the word "map".
Thank you, again, for a helpful reply to my post.
So, rather than an academic interest in frost line depths generally, you
actually looking for data for a specific locating in which you were
for a deck?
You really are a jerk.
Ask your local building permit folks, and stop wasting the time and
energy of the folks who regularly post here who give decent responses.
I'm not the google guru.
You, however, looking for frost line data for a specific location for a
specific deck application should have enough sense to ask the local
building permit / code folks.
You go straight to the bit bucket.
Don't believe the map, it shows my area at 35 inches, where the legal depth
requirement is 48" and frost has been found at 60 inches. You need to check,
with a simple phone call, or possibly your town's web site, to find what the
legal depth requirement for frost proofing is in your locality.
It would seem that your local county extension agent would have that info.
Frost lines vary depending on severity of winter. Another way to find
out is to call a local cemetery. Gravediggers deal with frost all the
The map shows 27" for my area. I called the County Extension service & they
said it was 42".
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Retired Shop Rat: 14,647 days in a GM plant.
Now I can do what I enjoy: Large Format Photography
-- re: Don't believe the map
Do believe the map. It shows the official frost line, as determined by
the U.S. Department of Commerce Weather Bureau, for the areas
The map does not purport to tell us how deep to place our foundations
or fence posts. That depth, as many have mentioned in this thread, is
determined by whatever agency is responsible for the building codes in
our area. There are many more factors, besides the frost line, that go
into how deep to place a foundation or fence post in any given area.
So go ahead and believe the map - but only for what it is telling us.
- Ask the inspector that needs to measure your holes before you pour
- footings. Just because a map says something, does not mean your
- municipality has a different depth they mandate for post holes
I dug ten 48" deep holes for my deck in very sandy soil. Between the
time I dug them and the time the inspector was due to come to the
house, it was expected to rain. I covered each hole with a scrap of
wood to keep the rain out so they wouldn't collapse.
The inspector came out on a drizzly day and as my wife stuck her head
out of the window, he slid one of the covers off with his foot and
asked my wife "Is that a 48" hole?"
Wife: "Yes it is."
Inspector: "And I'll bet there's a 48" hole under every one of those
pieces of wood, right?"
Wife: "Yes, there is."
Inspector, sliding the cover back over the hole, "OK, you're all set."