Hmmm,looks to Me that the front porch was planned from the initial set,maybe not. If it was designed to accept it then it should be fine.
Now that back lean-to thing(no offense meant but it is ugly)could be the source of some problems,maybe more than it is worth. Deffinetly check under it to see if it has supports near the home or if it is attached with a ledger board and adding to the weight of the back wall of the home as Yanita/Greg suggested.
I would suspect the foundation goes into the ground deeper than the frostline in Your area,and,if the footing is properly done it *should* support the weight of the house plus snow load plus,possibly,the lean-to and it's snow load.
For many years now I have thought/said that footings,under basement and/or frost walls *should* be wider as it is the "foot" the entire perimeter stands on,,works like a snowshoe for all intents and purposes,keeps the weight from sinking. Proper soil compaction under the footing/piers is another thing.Type of soil and good drainage(tiling)is another thing. Any one of these things or any combo can make for probs.
Blocking that sits on top of the ground is subject to frost heave and the amount of moisture frost has to work with compounds that problem. Perimeter blocking should never sit on top as there is more moisture soaking over.
When I helped the park owner pour the piers for My 14x70 I suggested pouring the end piers 3' in from the ends,He was going to put them right at the end,I saw no prob with a 3' cantilever and we went with that,worked well.
The hairline cracks should be no problem *if* there is enough rebar in the frostwall and footing and *if* the footing is deep enough and *if* the soil under the footing was compacted well. [[[Every buildings well being starts with the concrete man]]]. It is also worth mentioning(IMO) that sandy soil should have even wider and stronger footings,it is the same with perpetually moist soil.
When/if I build My own house the concrete will be so overdone I could build to the sky and have no settle probs! Heh heh,,overdone like this reply is!
![Smile :)](./images/smilies/icon_smile.gif)
Sorry. Do Ya forgive Me?!?!
Dean
PS- I have 2 friends(brothers) that have worked concrete for many years,the younger brother said the older one would probably refuse to pour concrete that was beyond specs for any given project! Job security or what?!?! Someday I wanna sit down with the older bro and see if that is truly the case. Building anything important that is,,well,,"planned" to fail long before it has to seems foolish to Me.