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Questions about stem wall and footing below frost line cold climate questions

A

atvjoel

Registered User
Joined
Aug 1, 2021
Messages
124
Location
Alaska
I am building a personal home on a hillside lot about a 10% or 15% grade. Top 2' of organics have been removed and native soil underneath is a sandy gravel. I am in Alaska outside City Limits so we are on International Building Code. I am building 24x64 ranch style single story.

Question 1 - Does code require you to be below the frost line if you are not on top of a water susceptible soil? I know ideally in my area your footing will be 42" down just specifically asking for code.

Question 2 - I read you can have higher then a 4 ft stem wall as long as not more then 4 feet are exposed without fill around it or it has to be engineered. If I build a 6' stem wall and then backfill about 42" of material around the footing and stem wall with sandy gravel (pitrun) after the stem wall is poured? Would this be acceptable and I qould not have to have engineered stem wall.

Thanks for your help
 
to add I am on SP soil. I am wondering what "unbalanced fill" is considered with 48" max stem wall height without engineering. If I "balance it" then I would not need an Engineer? As in backfill with SP Soil and compact both sides, would it now be "balanced" with 6' stem wall?
 
Welcome!

Looks like you are new here, and have multiple posts.

So yes, code would require that bottom of footing will be below whatever frostline has been determined by the AHJ.

As far as "unbalanced file", typically that can be mitigated with your floor framing system. But yes, backfilled and compacted on both sides would do it.

Be aware, if your floor framing is withing 18" of the earth below, treated lumber, for the framing system, will be required. Sheathing also if within 18".

I am NOT and engineer. ;)

R317.1 Location required. Protection of wood and woodbased
products from decay shall be provided in the following
locations by the use of naturally durable wood or wood that is
preservative-treated in accordance with AWPA U1.

1. Wood joists or the bottom of a wood structural floor
where closer than 18 inches (457 mm) or wood girders
where closer than 12 inches (305 mm) to the exposed
ground in crawl spaces or unexcavated area located
within the periphery of the building foundation.
 
fatboy said:
Welcome!

Looks like you are new here, and have multiple posts.

So yes, code would require that bottom of footing will be below whatever frostline has been determined by the AHJ.

As far as "unbalanced file", typically that can be mitigated with your floor framing system. But yes, backfilled and compacted on both sides would do it.

Be aware, if your floor framing is withing 18" of the earth below, treated lumber, for the framing system, will be required. Sheathing also if within 18".

I am NOT and engineer. ;)

R317.1 Location required. Protection of wood and woodbased
products from decay shall be provided in the following
locations by the use of naturally durable wood or wood that is
preservative-treated in accordance with AWPA U1.

1. Wood joists or the bottom of a wood structural floor
where closer than 18 inches (457 mm) or wood girders
where closer than 12 inches (305 mm) to the exposed
ground in crawl spaces or unexcavated area located
within the periphery of the building foundation.
Click to expand...
Ya I should have added more detail, reason for the question is because I was half tempted to abandon doing the crawl space and just do a slab and did read about below frost line reading through code but doesnt really make that much sense with a heated slab, but I do get it because if moisture gets under there and does freeze, heaving can occur.
I am a License Contractor but I am not a seasoned veteran building in Alaska and not a code wizard about cold climate. This is my video about what I am up against. I am building out of pocket and what I think I am going to do is just proceed forward with the crawl space and place the footing at this grade, build a 5 or 6 ft stem wall and then backfill around the stem wall so it is 42" below grade and I am not exceeding the 48" rule for "unbalanced fill".

I did read another section on chart and I may be reading it wrong but says if you have SP soils and you have 8" stem wall you can do up to 6' stem wall with "unbalanced fill" but obviously still the frost line issue occurs. I appreciate handholding I am on shoestring budget just trying to make a home for my family. I moved back to Alaska for work and last houses I built here I didnt inspect.
 
fatboy said:
Welcome!

Looks like you are new here, and have multiple posts.

So yes, code would require that bottom of footing will be below whatever frostline has been determined by the AHJ.

As far as "unbalanced file", typically that can be mitigated with your floor framing system. But yes, backfilled and compacted on both sides would do it.

Be aware, if your floor framing is withing 18" of the earth below, treated lumber, for the framing system, will be required. Sheathing also if within 18".

I am NOT and engineer. ;)

R317.1 Location required. Protection of wood and woodbased
products from decay shall be provided in the following
locations by the use of naturally durable wood or wood that is
preservative-treated in accordance with AWPA U1.

1. Wood joists or the bottom of a wood structural floor
where closer than 18 inches (457 mm) or wood girders
where closer than 12 inches (305 mm) to the exposed
ground in crawl spaces or unexcavated area located
within the periphery of the building foundation.
Click to expand...
I am also lost on R404.1.7 where is says you cant place backfill on unbraced stem wall or if its not anchored to floor above if its over 4ft, seems a little crazy to me because if you are not backfilling on wet concrete seems way overboard. Unless it means if you are placing more then 4ft of fill, which would make sense.

I just need to be about to backfill 42" of fill without giant headache. I have a private inspector but cant blow his phone up with questions. I am creating video channel so people can learn from what I learn. I appreciate any hand holding.
 
The exception to R404.1.7 allows you to place less than 4 ft. of unbalanced fill before the floor is framed.
 
Will you be using any 2-inch rigid Styrofoam on the inside of the stem wall and below floor? Just curious how its down in Alaska?

Where's Alaska Joe?
 
Pcinspector1 said:
Will you be using any 2-inch rigid Styrofoam on the inside of the stem wall and below floor? Just curious how its down in Alaska?

Where's Alaska Joe?
Click to expand...
Yes I will be placing 2 inch foam. I am using Poly Spray Foam for insulating the entire home except attic I am flash sealing and blowing it in with fiberglass to R value of 5,000,000 haha jk. I went underground with all my sewer, didnt want to hang it from floor joists
 
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