Checking sealed paint over time
Sealing does not take the lead away, so the surface needs looking at. Check for chips, cracks, bubbling and worn edges, especially at corners and low on walls. Repair the coating, or plan removal if it keeps failing. Tell a future buyer and any contractor where lead paint has been sealed, since sanding or cutting through the seal disturbs the lead beneath.
What affects the cost
Prep drives encapsulation: cleaning and fixing the surface, testing it, the amount of area and the number of coats a product needs. Enclosure adds materials and carpentry, and a job designed to last 20 years or more adds the abatement notice, plan and clearance.
Sealing starts with knowing what the paint contains, which lead paint inspection and testing covers, and where sealing will not hold, exterior lead paint removal covers the removal side. Livermore Lead Paint Removal links every service on its homepage.