PEX-A vs PEX-B
PEX-A kinks heal with a heat gun. PEX-B kinks need a coupling.
Tested and reviewed by Jonathan West · Updated October 12, 2026 ·how we research these
Cross-linked polyethylene (PEX) comes in types A and B, and PEX-A is ahead on several attributes that Uponor's comparison lists. For a repair, though, the tubing already in the wall decides which fittings you can use.
PEX-A can be kink-repaired with a heat gun and pairs with expansion fittings. PEX-B cannot be kink-repaired, so a coupling must be installed, and it typically pairs with insert fittings secured by a crimp tool. At DIY Repair Guide, we compiled this comparison from that one article, and Uponor makes PEX-A, so its claims favor its own product.
PEX-A or PEX-B
On the attributes Uponor compares, PEX-A is ahead on flexibility, kink repair, fitting options, flow, and freeze resilience. PEX-B has fewer strengths in the article. It is approved for expansion fittings, and the article pairs it with smaller-diameter insert fittings.
Bends are the first place the two types differ. Uponor says PEX-A's flexibility allows the tightest bend radius, which removes fittings at each change of direction. PEX-B is less flexible than PEX-A, so the article's bend claim applies to PEX-A alone.
Kink repair is one difference. Uponor says PEX-A has thermal memory that allows a kink repair with heat from a heat gun. PEX-B cannot be kink-repaired, so a coupling must be installed at the kink.
For a new run, the verdict is PEX-A, because the article's comparison favors it on flexibility, kink repair, fittings, flow, and freeze. For a repair, the verdict is set by the pipe already installed, since a repair has to use fittings made for that tubing.
PEX-C is a third type that this comparison does not cover.
| PEX-A | PEX-B | |
|---|---|---|
| Bend and flexibility | Most flexible. Tightest bend radius, which removes fittings at direction changes (Uponor). | Less flexible than PEX-A. |
| Kink repair | Repairable with heat from a heat gun, because of thermal memory. | Cannot be kink-repaired. A coupling must be installed. |
| Typical fitting | Expansion-style fittings, which suit larger diameters. | Insert-style fittings secured by a crimp tool, which suit smaller diameters. |
| Expansion fittings | Supported by its elasticity. | Approved, but it lacks PEX-A's elasticity and can microcrack when expanded. |
| Flow through fittings | Pipe and fitting diameters match, which Uponor links to superior flow. | Insert crimp fittings restrict flow and lower system performance, per Uponor. |
| Freeze behavior | More resilient where freezing occurs, per Uponor. | The article makes no freeze comparison claim. |
| Shared traits | Resists corrosion, pitting, and scale buildup. | Resists corrosion, pitting, and scale buildup. |
| Drawback Uponor names | Expansion can delay return to original size, which can need a heat gun. Uponor calls this its only con and ties it to cold climates. | Microcracks when expanded. A kink in a slab is harder to deal with, per Uponor. |
Matching Fittings to PEX-A vs PEX-B Tubing
Match the fitting system to the tubing type, because Uponor pairs each type with a different fitting style.
PEX-A pairs with expansion fittings. Uponor says PEX-A's elasticity supports larger-diameter expansion fittings, and the matching pipe and fitting diameters are the reason it cites for better flow.
PEX-B typically pairs with insert fittings secured by a crimp tool. Uponor says PEX-B is approved for expansion fittings but lacks PEX-A's elasticity, and it can experience microcracks when expanding. Uponor also says insert crimp fittings restrict flow and lower system performance, which matters because insert fittings are the usual PEX-B match.
Diameter is part of the match. PEX-B works best with smaller diameters in the article, and PEX-A's expansion fittings are sized to match the pipe. Compare the size of your tubing with the size of the fitting you plan to buy, and use our pipe size chart for the sizes.
Do not improvise a connection. The article does not say whether PEX-A and PEX-B can be joined, so a mixed join has no answer in this comparison. Brand compatibility is also outside the article, which does not say whether one brand's fittings fit another brand's tubing.
Read the installation instructions the tubing maker publishes for your product before you cut, expand, or crimp anything. Use only the fittings those instructions name for that tubing.
Kinks, Slabs, and When to Call a Plumber
A kink in PEX-A can be repaired with heat, and a kink in PEX-B needs a coupling installed.
Uponor credits PEX-A's thermal memory for making a heat-gun repair possible. The same article says expansion fittings can delay PEX-A from returning to its original size, which can also need a heat gun. Uponor calls that its only con and ties it to cold climates.
Slab work is one place the two types differ. Uponor notes that in a slab, where some jurisdictions do not allow connections, a PEX-B kink is harder to deal with.
The article does not name those jurisdictions or say which allow a connection in a slab. Local code decides that, and the article does not list the local rules, so a slab kink needs a local answer before any cutting starts.
Call a licensed plumber for any slab kink, any repipe, and any repair your local code requires a licensed plumber to make. The article does not cover permits, so this comparison cannot say which work needs one.
How to Weigh Uponor's Claims
Uponor makes PEX-A, and its article argues for PEX-A throughout. That does not make the claims false, but each comparison comes from the maker of one of the two types.
The article publishes no prices, pressure or temperature ratings, lifespans, code approvals, or brand-by-brand compatibility, so this comparison gives none of them. This comparison has no independent test data for either type.
Weigh the PEX-A claims as the maker's position. Its statements about PEX-A's own kink, flow, and freeze behavior are direct claims about its product.
Weigh the PEX-B side as thin. The article's points about PEX-B are mostly what it lacks compared with PEX-A, and it makes no freeze comparison claim for PEX-B.
A reader who needs an answer on freezing, mixed joins, or local rules should ask a licensed plumber, because the article cannot supply one.
Who This Is Not For
This comparison is not for anyone who needs a price, a pressure rating, a lifespan, or a code approval for PEX-A or PEX-B. The article publishes none of them, so the comparison gives none.
It is not for anyone planning to join PEX-A to PEX-B, or to use a fitting from another brand, without a licensed plumber's review. Call a licensed plumber for that job, and use our plumber cost guide to plan the visit.
It is not for slab kinks either. Call a licensed plumber, because the article says that repair is harder in a slab.
If you want a full repipe price, start with the repipe house cost page. This comparison does not price tubing or fittings.
What Would Change Our Answer
The new-run verdict changes if a local rule or a maker's instruction rules out PEX-A for your job. This comparison cannot see either one, so the local rule decides.
The repair verdict is already set by the pipe. If the installed pipe is PEX-B, you use PEX-B fittings, and a kink needs a coupling.
The comparison changes with an independent source. A published test of PEX-B's freeze behavior or of mixed joins would answer the two questions this comparison cannot answer.
Your Next Step Before Buying Fittings
This comparison cannot tell you how to identify the type on an installed run, because the article does not describe it.
If you cannot tell which type is installed, ask a licensed plumber before you buy fittings or cut any pipe.
Start by finding out which type is in the wall, then buy only the fittings made for that type.
Common questions
Can you mix PEX-A and PEX-B?
The Uponor article does not say whether PEX-A and PEX-B can be joined, so this comparison gives no answer on mixing. Do not join them with a fitting made for the other type. For any joint between the two, call a licensed plumber before you cut.
Which is better, PEX-A or PEX-B?
PEX-A is ahead on several attributes the Uponor article compares, including flexibility, kink repair, flow, and freeze resilience. For a repair, the type already installed decides the fitting, so the ranking matters most for a new run.
Can PEX-B use expansion fittings?
Yes, Uponor says PEX-B is approved for expansion fittings. The article also says PEX-B lacks PEX-A's elasticity and can microcrack when expanded, and it works best with smaller-diameter insert fittings secured by a crimp tool.
Can you repair a kinked PEX-B?
No, PEX-B cannot be kink-repaired with heat, so a coupling must be installed. Uponor says a PEX-B kink in a slab is harder to deal with, and some jurisdictions do not allow connections there. Call a licensed plumber for any kink in a slab.
Is PEX-B vs PEX-A a different comparison?
No, it covers the same two types. The table, verdict, and limits above apply in either reading order, and the source's claims still favor PEX-A.
What is the main drawback Uponor names for PEX-A?
Uponor says expansion fittings can delay PEX-A from returning to its original size, which can require a heat gun. It calls this the only con and ties it to cold climates.