A building permit is a dated announcement that money is about to be spent on a specific address. What is less obvious is that it often announces a SECOND permit, weeks later, from a different trade. Across 14,656 Massachusetts addresses that filed more than one trade, 21 pairs run reliably in one direction - and the gaps are long enough to be useful: Deck/Porch is followed by gas 87% of the time, a median 47 days later.
Two things had to be ruled out before any of this could be published. Co-occurrence is not sequence, so a pair appears here only if it runs one way at least 65% of the time across at least 40 addresses. And a same-day pair is not a sequence at all - it is one job filed as two permits on one morning. 2 pairs were excluded on exactly that basis, and they are listed further down rather than quietly dropped.
Read a row as: when the first trade files at an address, the second follows this often, this many days later. The middle-half column is the interquartile range, so it is the window worth watching rather than a single number.
| First | Then | Runs this way | Median gap | Middle half | Addresses |
|---|---|---|---|---|---|
| Deck/Porch | Gas | 87.2% | 47 days | 19-59 days | 41 |
| Kitchen/Bath | Gas | 82.3% | 31 days | 13-54 days | 79 |
| Deck/Porch | Plumbing | 80.4% | 47 days | 19-57 days | 41 |
| New Construction | Kitchen/Bath | 76.2% | 29 days | 14-57 days | 32 |
| Addition | HVAC | 75.4% | 40 days | 14-70 days | 46 |
| Kitchen/Bath | HVAC | 75.0% | 42 days | 20-80 days | 69 |
| New Construction | Plumbing | 75.0% | 49 days | 28-84 days | 39 |
| New Construction | HVAC | 75.0% | 78 days | 28-106 days | 30 |
| Kitchen/Bath | Plumbing | 74.5% | 22 days | 8-41 days | 295 |
| Kitchen/Bath | Electrical | 72.7% | 23 days | 11-42 days | 263 |
| Deck/Porch | HVAC | 72.5% | 57 days | 44-74 days | 29 |
| Renovation/Remodel | HVAC | 71.1% | 62 days | 30-97 days | 275 |
| Renovation/Remodel | Plumbing | 70.1% | 34 days | 14-59 days | 1,209 |
| Renovation/Remodel | Gas | 70.0% | 48 days | 21-83 days | 456 |
| Deck/Porch | Electrical | 70.0% | 25 days | 9-56 days | 77 |
| Addition | Electrical | 69.8% | 21 days | 10-43 days | 88 |
| Addition | Plumbing | 69.6% | 22 days | 12-56 days | 48 |
| Building | Plumbing | 69.5% | 28 days | 13-55 days | 456 |
| Roofing | Windows/Doors/Siding | 67.8% | 21 days | 6-57 days | 82 |
| Windows/Doors/Siding | Deck/Porch | 67.5% | 24 days | 12-58 days | 27 |
| Electrical | Fire/Sprinkler | 65.4% | 38 days | 20-85 days | 89 |
The longest reliable gap here is new construction to hvac, at a median 78 days. That is not a statistical curiosity - it is about 11 weeks of notice. A permit filed today at an address is, more often than not, a job for a different trade at that same address next month. The permit record is the only place that shows up before the work does.
These run one way just as strongly, and they are still not sequences. A median gap of a day or two means both permits were filed for one job - the trades did not follow each other to site, a clerk entered two rows. They are here because leaving them out silently would make the table above look cleaner than the data is.
| First | Then | Runs this way | Median gap | Addresses |
|---|---|---|---|---|
| Gas | Plumbing | 84.0% | 0 days | 2,358 |
| Electrical | Solar | 77.5% | 2 days | 183 |
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At an address that files permits from more than one trade, does one trade reliably come first, and how long is the gap?
Permits grouped by source and normalised street address. An address carrying more than 12 permits is dropped as a commercial site or subdivision rather than a house having work done. For each pair of trades at an address only the FIRST appearance of each trade is used. A pair is reported only if it appears at 40 or more addresses and runs one way at least 65% of the time. 14,656 of 56,426 addresses carry more than one trade.
Every source that publishes a street address.
Addresses are matched within a single source only, never across towns, so a common street name cannot merge two properties. No pair had to be dropped for disagreeing across source groups.
Two limits, both real. The dataset spans about six months, so a gap longer than that is invisible and every median here is biased short. And 0 sources are truncated to their newest 0 records, where the EARLIER permit at an address is the one most likely to be missing - which could manufacture false orderings. Every pair was therefore computed separately on capped and uncapped sources; both figures are in the evidence file, and any pair the two groups disagreed about was dropped.
Computed 2026-08-20 from a dataset fetched 2026-11-03. Download the figures behind this page (JSON).
Deck/Porch followed by gas: at addresses that file both, it runs in that order 87% of the time, a median 47 days apart.
Between 21 and 78 days depending on the pair. The longest reliable gap is new construction to hvac.
This says nothing about who does the work. Contractor names are never used in any analysis on this site. It is a statement about permits at an address.
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MassPermits. “What permit follows what in Massachusetts, and how long after”. Updated 2026-11-03. https://masspermits.com/research/permit-sequence
Method: https://masspermits.com/research/methodology · Corrections: https://masspermits.com/research/corrections · Licence: CC BY-NC 4.0