Structural P.Eng recommendation GTA

Sorry about your luck.

Seems like you may need a forensic engineering firm to look at this. Problems like this can be troublesome, especially if it goes into litigation. Tarion warranty may help too, but they won't act until the crack is wider than 6mm. You can also try going through your insurance, and they will bring in their own forensic engineering firm, and they will go after your contractor for you.

I am a structural engineer myself, and I used to work for a forensic engineering firm, as a structural forensic investigator. Unfortunately, I do not have the capacity to help you myself right now. There could be a number of issues that could cause your crack, eg. foundation issue (incl. inadequate support or depth), geotechnical issues (ie. poor soils conditions or drainage issues), or possible design issues (I noticed that there are different types of foundation materials, some poured concrete and some blocks - poor design could cause stress points in the wall, causing sheer cracks). Unfortunately without a proper site investigation, it is difficult to pinpoint the problem.

I suggest you try some of the options above. If it was me personally, I would probably go through insurance. They will bring in their own forensic investigation team, bridge formal communication with the contractors and their insurance, and equipped to go through litigation if necessary (most costs will be covered by them). This would save you the trouble and headache of dealing through this yourself. If you want to tackle this yourself, there are a number of forensic engineering firms you can try:

http://arconforensics.com/
https://www.30fe.com/
http://expcep.com/

Good luck with your house... all the best!

I used Byron Escobar from TBM Engineers during my kitchen reno a year ago when removing a structural wall. Was happy with the service.

http://tbmengineers.com/who-we-are/

I used KH Davis for my reno. They were great to deal with.

Any recommendations for the Mississauga area?

TIA