Replies

1. 
   andy_engel | Feb 09, 2022 06:04am | #1

   Footings need to rest on undisturbed earth. You might have that 5 ft. out from the house, so you could use a 42 in. deep footing there, but the return walls would almost certainly need to go all the way down.

2. 
   unclemike42 | Feb 09, 2022 06:28am | #2

   Are you planning to do the work yourself?

   Stepped footers are not uncommon. every house with a basement and attached garage at grade level has a couple.

   the principal is that footers have to be on undisturbed (or properly prepared (meaning compacted and selected) soils.

   The footer under the walls that you mostly bury only need to be below the frost depth.

   You can handle the transition from the bottom of the basement wall a couple ways. You could finish the basement, backfill while paying attention to properly compacted and selected material to support the higher footings. Then pour footings just below the frost depth.

   You can also extend the basement footer where the other walls will be and build up the first foot or so of foundation wall close to the basement wall there, adequately bridging to the higher footer at or below 42 inches deep.

   You will want to secure the porch and sunroom foundation to the concrete/steel inside the basement wall ICF.

3. 
   user-7641575 | Feb 09, 2022 08:26am | #3

   Thanks for the replies!

   Mike, when you say: "You will want to secure the porch and sunroom foundation to the concrete/steel inside the basement wall ICF." is there a way around this? I am concerned about the thermal bridging there would be if the uninsulated porch foundation is in contact with the ICF concrete wall. Would I have to do a free standing porch with 4 foundation walls in order to avoid this?

4. 
   mikemahan3 | Feb 09, 2022 01:27pm | #4

   it would seem that the end walls are not bearing any load but are only there to support the stone veneer. I'd make them 42" deep on compacted fill. Run some threaded rod through the ICFs into the stem wall. You could use rebar, but I think the plated rod would be better through the foam. Is there going to be stone over the ICFs?

5. 
   mikeljon | Feb 09, 2022 03:04pm | #5

   If the concrete stem wall is supporting the loads of the porch and the roof, besides the undisturbed earth consideration, I would think your engineer will be requiring your footings to be sized and their depth determined by their zone of influence not interfering with the house's foundation...Everything anywhere near another footing my engineer has spec'd as either bearing at the same level of the existing footing, or located and deep enough to not intersect the existing wall at the 45 degree from the bottom of the new footing.