Get an independent engineer's assessment first, before any repair company walks the property. Ask a good local real estate agent for a referral to a structural or geotechnical engineer whose only job is to assess the home. A company that both diagnoses the problem and sells the fix has an obvious incentive to find a bigger problem. Independence removes that incentive. With a neutral report in hand, you know what you're actually dealing with, and you can take that same defined scope to multiple repair contractors for competitive bids. That usually gets you a truer picture and a better price than trusting a single all-in outfit's diagnosis. It also puts you in a stronger spot as a seller. You can disclose accurately, and you can price or negotiate any repairs from facts instead of a worst-case sales pitch.