What a home's permit history can and can't tell you before you reach out
Building permits are one of the best public signals for home-service prospecting. Here is what they reveal, where they mislead, and how to match them to homes without guessing.
The MapKnock team · · 5 min read
When a homeowner replaces a roof, installs solar or swaps a furnace, there is often a building permit. Many cities and counties publish those records. For anyone selling home services, they are one of the few public signals that speak directly to the work you do.
What permits tell you
- Roughly how old a system is. A reroof permit from 2004 says more about the roof than the year the house was built.
- What is already installed. A solar permit means a solar pitch is the wrong pitch, but a battery or expansion conversation might be the right one.
- Which neighborhoods are active. Clusters of recent permits show where homeowners are investing, and where neighbors may be weighing the same project.
Where permits mislead
- Not all work is permitted. The absence of a permit is not proof that nothing was done. Treat “no permit on record” as unknown, not as old.
- Descriptions are messy. Permit types and free-text descriptions vary between jurisdictions and even between clerks. Classifying them into “roofing” or “solar” takes care.
- Coverage varies. Some jurisdictions publish years of history in a clean format; others publish nothing, or only recent records.
Matching permits to the right home
The hard part isn't reading a permit; it's attaching it to the right property. Addresses are written many ways, units get dropped, and parcels get split or merged. A wrong match is worse than no match, because your team will repeat it to a homeowner.
A careful process looks like this:
- Match on the parcel number first, when the permit has one.
- Otherwise match on a standardized address, and accept it only when exactly one property fits.
- Send anything ambiguous (several candidates, or a match that only works after dropping a unit) to a person.
- Keep those human decisions, so re-importing the data doesn't undo them.
How MapKnock uses permits
MapKnock follows that process. Permits show on the property record as a timeline, labeled as public permit records, and feed signals like roof age and existing solar. Coverage is growing jurisdiction by jurisdiction: today it includes solar and roofing permits in select markets, and customers can request the jurisdictions they work. Read more on the permit intelligence page.