I agree, check all the doors and windows, open and close them.... What kind of foundation is it? Any defects, upgrades needed, etc.? You need to evaluate the totality of defects...to make a better determination.

Also, don't forget the "soil" ....... You may want to advise your clients to get a soils report or geo-technical evaluation

Just make sure to let your client know that you are not a structural engineer, you do not do soils evaluations, etc. Cracks happen in surfaces, and all structures have some degree of movement that causes cracks.

Hope this helps,
Justin
Orange County Home Inspectors, Certified Home Inspector, property inspectors, Huntington Beach Home Inspection, Laguna Beach and Santa Margarita Home Inspection Services