Institutional plumbing
Lab fixtures, safety eyewash stations, and code-driven commercial fixture installs.
Government & DoD Mechanical Subcontractor
Licensed tri-state mechanical subcontractor for prime contractors and facility owners.
A mechanical sub who can't cross the state line stalls the award
Federal work in this corridor spans two borders: Portsmouth Naval Shipyard sits in Kittery, Maine, and Pease is in New Hampshire. JP Karos holds master-plumber licensure in NH, MA, and ME plus NH gas-fitting licensure, so one subcontractor covers the whole footprint without a licensing gap.
Built for prime contractors
We pursue mechanical subcontract work with prime contractors and construction managers serving federal and municipal facilities in our region, and we bring commercial past performance to the table: multi-boiler plant installs, process gas piping in food-production facilities, and institutional plumbing packages.
Licensed on both sides of the Piscataqua today, and relocating from East Hampstead to the Portsmouth area, a move that puts the shop minutes from Portsmouth Naval Shipyard and Pease.
Core competencies
- 01Boiler plant installation and replacement, residential through multi-boiler commercial
- 02Gas and process piping: natural gas, propane, and oil, permitted and inspected
- 03Heat pump and HVAC systems, Mitsubishi Diamond Contractor
- 04Commercial water heaters, institutional plumbing, and fixture packages
- 05Emergency mechanical response across the tri-state footprint
Differentiators
- 01Master-plumber licensure in NH, MA, and ME plus NH gas-fitting licensure, under one entity
- 02Owner-operated: the master plumber who signs the bid runs the crew
- 03Commercial past performance in food-production, chemical-adjacent, and multi-residential facilities
- 04Rapid mobilization within the Portsmouth, Kittery, and Pease corridor
Company data
JP Karos Plumbing & Heating LLC
238220 (Plumbing, Heating, and Air-Conditioning Contractors)
Related scopes bid under prime-held vehicles as applicable.
Fully licensed and insured
East Hampstead, NH (shop moving to the Portsmouth area)
Licenses (as printed)
New Hampshire
- NH PL M-2210287
- NH GF2212147
- NH-MBE2201473
Massachusetts
- MA PL M-17020
- MA HIC 207892
- MA PL CORP-4668
Maine
- ME PL MS-90020494
Reach the estimator directly
Send plans, a sub-bid scope, or a solicitation number. You'll get a direct answer from the license holder, not a call center.
One-page capability statement available on request.
Representative commercial work
Commercial and institutional past performance shown; federal task-order references provided as they are earned.
Commercial & Mechanical
Multi-boiler plants, commercial water heaters, process gas piping, and mechanical work for multi-residential buildings, restaurants, chemical and food-production facilities across NH, MA, and ME.
Five-boiler commercial plant
Full boiler bank with stainless venting and copper near-boiler piping in an occupied commercial building.
Food-production process gas
Permitted gas piping, regulators, and venting serving production equipment in a working food plant.
Need a licensed tri-state mechanical sub?
Send the scope. You'll get a direct answer from the master plumber who runs the crew.
- 21+
- Years in the trade
- 3
- States licensed
- 7
- Licenses held