# PEX Repiping in Philadelphia

> PEX repiping in Philadelphia homes: PEX-A or PEX-B, the right fittings and layout, and the City rule on where plastic water pipe may and may not be used.

URL: https://philadelphiafreedomrepipe.com/pex-repiping/

Flexible PEX supply lines run through a house's own walls and joists, in the occupancies where Philadelphia's code allows plastic water pipe, with metal where the code requires it.

Last Updated: October 26, 2026

**32 of 52** Whole-house or explicit water piping replacement permits in Philadelphia over 36 months that named PEX; one named copper

**75 ft** Height of an occupied floor above fire-access level beyond which Philadelphia's code calls for metallic water piping

**4 ft** Minimum developed length of copper or similar metallic pipe at a water heater's inlet and outlet under the EZ permit standards

**77.3** Days a year Philadelphia's low reaches freezing or below, on NOAA's 1991 to 2020 normals

[Philadelphia Freedom Repipe](https://philadelphiafreedomrepipe.com/) repipes houses in PEX across Philadelphia and nearby Delaware, Montgomery and Bucks County suburbs, in the buildings where the code allows plastic water pipe. PEX is crosslinked polyethylene tubing: flexible, listed for hot and cold drinking water, and joined with mechanical fittings rather than solder. It is the material most Philadelphia house repipes now use, and the reasons are practical. It also has firm limits under the City’s own plumbing code, and a few weaknesses that the installation has to account for. Licensed and insured contractors carry out the work; inside the city, a Philadelphia licensed master plumber oversees the job and pulls the L&I permit.

This page covers PEX specifically. For the full scope of replacing every supply line, see [whole-house repiping](https://philadelphiafreedomrepipe.com/whole-house-repiping/); for the metal alternative, see [copper repiping](https://philadelphiafreedomrepipe.com/copper-repiping/).

## Where Philadelphia allows PEX, and where it does not

Philadelphia writes its own plumbing code. The 2018 Philadelphia Plumbing Code, as amended effective April 1, 2024, allows nonmetallic water piping such as PEX in one- and two-family dwellings and apartments. Section P-605.4 then draws the line: any water supply piping that supplies or sits within any other occupancy has to be metallic. That catches the corner rowhouse with a store, office or salon on the ground floor, where L&I-approved scopes state that all supply piping for the commercial space shall be metallic.

Height is the second limit. Under P-605.4.1, metallic piping is required in a building with an occupied floor more than 75 feet above the fire-access level, with a narrow exception for piping inside individual dwelling units in new construction. A house never reaches that height, but a mid-rise apartment building can.

The third limit sits at the water heater. Philadelphia’s EZ permit standards call for at least 4 feet of developed length of copper or similar metallic pipe at the heater’s inlet and outlet, so a PEX system meets the heater through metal. The code also allows press-connect and push-fit joints above ground only. L&I’s [summary of the Philadelphia plumbing code amendments](https://www.phila.gov/media/20240226150355/PB_022_FAQ_Summary-of-2018-Philadelphia-plumbing-code-amendments.pdf) sets out these sections, and the guide [is PEX allowed in Philadelphia](https://philadelphiafreedomrepipe.com/guide/is-pex-allowed-in-philadelphia/) goes through them one at a time.

In the suburbs, townships enforce the statewide Pennsylvania Uniform Construction Code, which adopted the 2021 International Plumbing Code effective January 1, 2026; each township or borough’s own permit and contractor rules apply.

## Why most Philadelphia house repipes are PEX

L&I’s permit records show the trend plainly. Of 52 whole-house or explicit water piping replacements permitted between October 26, 2023 and October 25, 2026, 32 named PEX and one named copper; the recurring approved wording is “install new PVC and PEX piping throughout single family dwelling”. The reasons come from the houses.

A rowhouse has party walls on both sides and plaster on the rest. Rigid pipe needs a straight path or a fitting at every turn, and every fitting inside a finished wall means an opening. PEX bends around framing, can be fished down a stud bay from an opening at the top, and comes off a coil in long continuous runs, so a riser from the basement to the second-floor bathroom can go up with few or no hidden joints. Fewer joints in a wall means fewer openings and fewer places to leak. That is the main practical case for PEX in an old house, and it is why the [guide to repiping plaster walls](https://philadelphiafreedomrepipe.com/guide/repiping-plaster-walls/) assumes PEX for most of its examples.

None of this makes PEX the right material for every house. The [PEX vs copper repipe guide](https://philadelphiafreedomrepipe.com/guide/pex-vs-copper-repipe/) sets out where copper is the better or the required choice.

## PEX-A and PEX-B

All PEX is polyethylene crosslinked so it keeps its shape under heat and pressure. The letters describe how the crosslinking was done, and that changes how the tubing behaves on the job.

**PEX-A** is the most flexible. It bends tighter without kinking, and a kink can usually be recovered with heat. It is the tubing used with expansion fittings, where the tube end is expanded, pushed over the fitting and shrinks back to grip it. The fitting bore stays close to the tube’s own inside diameter.

**PEX-B** is stiffer and holds a coil memory longer, so it needs more bend supports and fastening to lie flat. It is usually joined with crimp or clamp rings, or press sleeves, on insert fittings. Insert fittings narrow the bore at each joint, which matters on a long run with many fittings feeding a shower upstairs, and matters little on a short branch.

Both are listed for drinking water when made to the relevant standards, and both are installed by the manufacturer’s instructions and the [Plastics Pipe Institute’s PEX design guide](https://www.plasticpipe.org/PPIPAC/BuildingConstruction/Publications/PEX-Design-Guide.aspx). The important rule is consistency: one tubing and fitting system, matched to the listing, through the whole job.

## Manifold or trunk-and-branch

A **trunk-and-branch** layout runs larger mains, usually 3/4 inch, with smaller branches teed off to each fixture group. It uses less tubing and suits narrow rowhouse framing, where there may be one good chase to the second floor.

A **home-run manifold** layout gives every fixture its own line from a central manifold, each with its own shutoff. A single fixture can be shut off without losing the bathroom, and the manifold ports can be labeled by room. It needs more lines through the walls, which can mean a larger chase.

Many Philadelphia repipes combine them: a manifold in the basement for the first-floor fixtures and a trunk up to the bathroom with a small manifold or branch tees there. The [rowhouse repiping](https://philadelphiafreedomrepipe.com/rowhouse-repiping/) page shows how that plays out in a narrow plan.

## What PEX does not tolerate

PEX does fail when it is installed badly, and the installation has to answer for four things:

- **Sunlight.** Ultraviolet light breaks PEX down. Tubing is stored out of the sun and never left exposed outdoors or under a skylight.
- **Heat.** PEX stays clear of flues, recessed lights and the water heater’s hot connections; the code’s metallic section at the heater handles the last.
- **Rodents.** Mice and rats can chew plastic tubing in basements and crawl spaces. Tight runs, sleeves at openings and sealing gaps reduce that exposure.
- **Freezing.** Philadelphia averages 77.3 days a year with a low at or below freezing on NOAA’s 1991 to 2020 normals. PEX stretches more than copper as ice forms, but fittings and valves on a frozen line can still crack. New lines stay inside heated space where possible and are insulated where they cannot.

PEX also expands and contracts with temperature more than copper does, so long runs get room to move rather than being clamped tight at both ends.

## Testing, flushing and closing up

Before any wall or ceiling closes, the new system is pressure tested with fixtures isolated so a weak joint shows on a gauge. After the cutover from old pipe, the lines are flushed and aerators cleaned, and each shutoff or manifold port is labeled. Openings close to the finish the quote names. The [guide to living through a repipe](https://philadelphiafreedomrepipe.com/guide/living-through-a-repipe/) covers water-off windows and daily routine during the job.

## Price, permit and who does the work

A PEX repipe of a typical home runs about $4,000 to $10,000 by area pricing, with large homes higher. For a one- or two-family dwelling, L&I lists the alteration permit at $50 for the first 7 fixtures and $22.50 for each additional one. The [repiping cost guide for Philadelphia](https://philadelphiafreedomrepipe.com/guide/repiping-cost-philadelphia/) breaks the drivers down, and the [Philadelphia repipe permit guide](https://philadelphiafreedomrepipe.com/guide/philadelphia-repipe-permit/) covers the application and inspection.

## Related resources

- [Galvanized pipe replacement](https://philadelphiafreedomrepipe.com/galvanized-pipe-replacement/), the most common starting point for a PEX repipe
- [Repipe cost estimator](https://philadelphiafreedomrepipe.com/tools/repipe-cost-estimator/) built on the published ranges
- [Philadelphia plumbing code update](https://philadelphiafreedomrepipe.com/blog/philadelphia-plumbing-code-update/) for the pending 2021 code bill

## What's included

- A layout plan: trunk-and-branch, home-run manifold or a mix, chosen for the house
- PEX tubing and one listed fitting system used consistently through the job
- Metallic sections at the water heater inlet and outlet, as the Philadelphia code requires
- Supports, bend supports and protection sleeves where tubing passes framing or masonry
- Clearance from flues, recessed lights and other heat sources, and no exposed runs in sunlight
- Insulation on runs near outside walls or in unheated space
- Pressure test before walls close, a full flush, and labeled shutoffs or manifold ports
- The L&I permit, pulled by a licensed master plumber, and its inspection

## PEX fitting systems compared

|  | Expansion (cold expansion) | Crimp or clamp ring | Press sleeve |
| --- | --- | --- | --- |
| Tubing it suits | PEX-A, which is flexible enough to be expanded | PEX-B or PEX-A, by the fitting maker's listing | PEX-A or PEX-B, by the fitting maker's listing |
| How the joint is made | The tube end is expanded, slipped over the fitting and shrinks back onto it | A copper or stainless ring is squeezed over the tube on an insert fitting | A sleeve is pressed over the tube onto the fitting with a press tool |
| Flow through the fitting | Fitting bore close to the tube's inside diameter | Insert fittings narrow the bore at each joint | Insert fittings narrow the bore at each joint |
| What to check | Expansion is slow in cold weather; the tube needs time to recover | Each ring must be checked with a go/no-go gauge | Press-connect joints are allowed above ground only in Philadelphia |
| Where it fits a repipe | Long runs and manifolds where bore matters | Tight spaces and short branches | Quick joints with a consistent tool |

## Guides for this work

- Learn [Is PEX Allowed in Philadelphia?](https://philadelphiafreedomrepipe.com/guide/is-pex-allowed-in-philadelphia/)What the Philadelphia Plumbing Code says about PEX water pipe: where it is allowed, where metal is required, the rules at the water heater and the fittings, the pending code bill, and how the suburbs differ.
- Decision Guide [PEX or Copper: Which Is Better for Repiping a Philadelphia House?](https://philadelphiafreedomrepipe.com/guide/pex-vs-copper-repipe/)How PEX and copper compare for a Philadelphia repipe: what the city code allows, how each handles Philadelphia water, cold basements and rodents, what each means for the walls, and which way each moves the price.
- Cost Guide [How Much Does Repiping Cost in Philadelphia?](https://philadelphiafreedomrepipe.com/guide/repiping-cost-philadelphia/)Typical ranges for a whole-house and a PEX repipe, what sits inside the price, the City's permit fees, and why two quotes for the same rowhouse can differ.
- Learn [How Long Does a Repipe Take When You Are Living in the House?](https://philadelphiafreedomrepipe.com/guide/living-through-a-repipe/)The schedule depends on floors, fixtures, access and the plaster, not on a standard number of days. How the work is staged so the water is off only at cutovers, and what to get ready before the first day.
- Learn [How Do You Repipe a House With Plaster Walls?](https://philadelphiafreedomrepipe.com/guide/repiping-plaster-walls/)Plaster on lath can be opened and closed cleanly if the openings are planned. Where the cuts go, how routing keeps them few, the three levels of patching, and what keeps the dust in one room.
- Learn [Do You Need a Permit to Repipe a House in Philadelphia?](https://philadelphiafreedomrepipe.com/guide/philadelphia-repipe-permit/)How the L&I plumbing permit works for a repipe in Philadelphia: when one is needed, who can apply, what the EZ permit covers, the published fee lines and surcharges, and what happens at inspection.

## 

1. First call You describe the house: rowhouse, twin or detached, how many floors and bathrooms, what the pipe looks like where you can see it, and what made you call. That sets up the walk-through.
2. Assessment The walk-through starts at the meter and main shutoff, traces the pipe up every floor, checks pressure and flow, and maps the routes and the openings. You get a written scope that says what is replaced and what stays.
3. The work A licensed master plumber pulls the L&I permit. New lines go in while the old ones keep the house running, then each section is cut over during a planned water-off window.
4. Completion The new piping is pressure tested and inspected, then flushed. Shutoffs are labeled, openings are closed to the finish the quote names, and you get a list of anything old that stayed in service.

## What this work looks like

Gloved hands using a cordless expansion tool on red PEX tubing in a rowhouse basement

Red and blue PEX lines in plastic clips along the basement joists, turning up through drilled holes

A brass PEX manifold with red and blue lines rising from a plywood board to the joists

A water heater with short copper connections at the top changing to red and blue PEX lines

Before

After

## PEX repiping questions

### What is the difference between PEX-A and PEX-B for a repipe?

They are crosslinked by different methods, and that changes how they handle. PEX-A is more flexible and is usually joined with expansion fittings whose bore stays close to the tube's. PEX-B is stiffer and is usually joined with crimp or press fittings on inserts, which narrow the bore at each joint. Both are listed for drinking water.

### Is a manifold or trunk-and-branch layout better for a PEX repipe?

Neither is better in every house. A home-run manifold gives each fixture its own line and shutoff, which helps later service but needs more lines through walls. Trunk-and-branch uses fewer lines and suits tight rowhouse framing. Many repipes mix them: a manifold for the first floor and a trunk up to the bathroom.

### Why do most Philadelphia house repipes use PEX?

Because of the houses. Rowhouses and twins have party walls and plaster, and PEX bends around framing and comes in long runs that can be fished down a stud bay, so fewer fittings sit inside walls and fewer openings are cut. L&I records show 32 of 52 recent whole-house repipe permits named PEX.

### Why are long PEX runs not clamped tight at both ends?

PEX grows and shrinks with temperature more than copper does, so a long hot line gets longer each time hot water runs through it. Clamped tight at both ends, it bows, rubs or pulls on fittings. Runs get loose supports, gentle offsets and room at the ends so the tubing can move without stressing a joint.

### What does a PEX repipe typically cost around Philadelphia?

About $4,000 to $10,000 for a typical home, by area pricing; large homes run higher. The number moves with the fixture count, floors, layout, how much plaster or tile has to open and how much patching follows. The water heater's required metallic section and any service line work are priced as part of the scope.

## Related services

### Whole-house repiping

Every hot and cold supply line from the main shutoff to the fixtures, replaced in the material the Philadelphia code allows for the building and pressure tested before the walls close.

### Copper repiping

Rigid copper supply lines for mixed-use buildings and other occupancies where Philadelphia requires metal, and for houses whose owners choose it, joined by press or solder with care around old framing.

### Rowhouse repiping

A repipe planned around the rowhouse itself: a service through the front wall, a long narrow basement, party walls on both sides and a bathroom one floor up.