# frost lines



## chrisherk

Anybody have any idea what the depth of the frost lines are? I cant find it in the International Residential Code, which New Hampshire uses. I always thought for a garage that has 2' of concrete sticking up' you need around 4' inthe ground (includes footing). The concrete guy was going to pour 4' walls and 2' of it is sticking out, which would've left 2'8" in the ground. Ive seen frost over 3' deep in this part of NH. Anyway I cant find a min. depth

chris


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## rino1494

Why will there be 2' sticking up??? Finished grade should be level with the top of concrete floor. 

Anyways, around here we always dig our frost footers 3' deep.


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## bassmaster

I Think in CT it is 42", jmic - would probably know for sure.


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## chrisherk

rino1494 said:


> Why will there be 2' sticking up??? Finished grade should be level with the top of concrete floor.
> 
> Anyways, around here we always dig our frost footers 3' deep.



2' is the finished grade around the whle house because of the height of the bulkhead. where are you penn? this job is in northern NH I was thinking 4' but i would like to see something in the code. 

chris


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## jmic

This area in Ct. goes by 42" for frost.


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## chrisherk

jmic said:


> This area in Ct. goes by 42" for frost.


Is that what the state code, or local inspector says?


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## jmic

Chris, 
Is what you're calling a bulkhead the little pc. of foundation wall between garage doors? Anyways from your finish garage slab elevation you should have probably ilike what your thinking 48" to bottom of your footings for frost.


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## PipeGuy

From http://www.bow-nh.com/codeenforcement.asp



> BOCA CODES:
> 
> As of 2002, the Town of Bow uses the 1984 BOCA Codes for residential buildings, and the 1999 BOCA Codes for commercial buildings.
> 
> Roof Loads: Both live load and snow load are 40Lbs/Sq Ft--- Commercial: 45-50 Lbs/Sq Ft
> Ground Snow Load: Commercial: 75-85 Lbs/Sq Ft
> Wind Pressure: 25 Lbs/Sq. Ft---Commercial 80-90 Lbs/Sq Ft
> Seismic Zone:2 --------------------------Frost line depth: 3 Ft.


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## jmic

chrisherk said:


> Is that what the state code, or local inspector says?


 Couldn't really tell you for sure, it's just common knowledge of what everyone does and the inspectors expect, so it must be code:w00t:  :laughing:


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## PipeGuy

see also http://met-www.cit.cornell.edu/reports/RR_96-1.html


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## rino1494

jmic said:


> Chris,
> Is what you're calling a bulkhead the little pc. of foundation wall between garage doors?



We call that a keyway.

To us, a bulkhead is vertical footer that runs b/n grade change elevations.


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## chrisherk

jmic said:


> Chris,
> Is what you're calling a bulkhead the little pc. of foundation wall between garage doors? Anyways from your finish garage slab elevation you should have probably ilike what your thinking 48" to bottom of your footings for frost.


the bulkhead is the outside basement stairs into the basement. For some reason they set that 2' down from top of foundation. That right there sets the grade around the whole house (flat lot).I just found in the Mass code, it says 48". I knew i was right, this concrete guy is putting garages and breezeways in too shallow. thanks, jmic

chris


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## PipeGuy

found it









"Extreme depth of frost penetration (in meters)"
http://www.ngs.noaa.gov/PUBS_LIB/GeodeticBMs/#figure13


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## chrisherk

rino1494 said:


> We call that a keyway.
> 
> To us, a bulkhead is vertical footer that runs b/n grade change elevations.


 I guess every body calls things different, I always thought a keyway is the tie-in from the bottom of the wall to the top of footing, to keep the wall from sliding off the footing. But what do i know.


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## chrisherk

PipeGuy said:


> found it
> 
> 
> 
> 
> 
> 
> 
> 
> 
> "Extreme depth of frost penetration (in meters)"
> http://www.ngs.noaa.gov/PUBS_LIB/GeodeticBMs/#figure13


 wow, i'm impressed


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## PipeGuy

I was kinda' surprised to see it. Down here the frost line is only 1/2 a meter but everything gets 4 feet of cover. What's that, a 2:1 safety factor?


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## Tom R

chrisherk said:


> I guess every body calls things different, I always thought a keyway is the tie-in from the bottom of the wall to the top of footing, to keep the wall from sliding off the footing. But what do i know.


Yeah, - - what I call a 'keyway' is a slot along the top of the footing to help prevent sliding.

Cool map, Pipe.


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## rino1494

Tom R said:


> Yeah, - - what I call a 'keyway' is a slot along the top of the footing to help prevent sliding.


I guess we are talking about poured walls here then. I haven't seen too many masons use a slot in the footer around here. Most use rebar sticking up.


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## jmic

rino1494 said:


> We call that a keyway.
> *We call a keyway a 2"x2" groove that runs around the footings under where the walls will be sitting so when the walls are poured they lock into the footings.*
> To us, a bulkhead is vertical footer that runs b/n grade change elevations.


*We just call these steps but have heard them refered to as bulkheads, I was just curious as to what Chris was refering to.*


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## jmic

chrisherk said:


> the bulkhead is the outside basement stairs into the basement. For some reason they set that 2' down from top of foundation. That right there sets the grade around the whole house (flat lot).I just found in the Mass code, it says 48". I knew i was right, this concrete guy is putting garages and breezeways in too shallow. thanks, jmic
> 
> chris


 Ok now I see what you're calling a bulkhead, we use precast Bilco Door Units, the Co. just comes and bolts them to foundation:thumbsup:


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## rino1494

jmic said:


> Ok now I see what you're calling a bulkhead, we use precast Bilco Door Units, the Co. just comes and bolts them to foundation:thumbsup:



same here


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## ContractorSon

The garage usually has a stemwall set upon the footing. (which is usually 3.5 feet deep in NE Ohio). They consider this to be an "exhaust curb" that will place the entry door 2 feet above the garage finished floor.


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