Write an offer contingent on a satisfactory home inspection within ten days of seller acceptance. Hire a licensed home inspector to thoroughly examine the house after you've had the offer accepted. The inspector will advise you of structural problems, presence of mold, etc., and approximate cost to repair or address deficiencies. Hire the inspector to tour the house within the first few days, leaving you time to arrange for any other contractors (e.g., roofers) to come out and give free estimates before the ten days elapses. Licensed home inspectors charge $250-$450 here in Michigan. They're well worth it. Find one near you on the Internet.