Shower Valve Extension Kits: Which One Fits Your Valve When It Sits Too Deep

The tile is up, or a second layer of backer board went on, and now the shower valve sits too deep behind the wall. The trim sleeve does not reach, the handle will not seat, or the screws come up short. Most makers sell shower valve extension kits for exactly this, but each kit is made for one valve family, not for a brand. This page shows how to measure the gap, how to find the family and trim in your wall, and which kit each maker lists. It also covers the cases where the maker says no kit exists.

Measure First: Is the Valve Really Too Deep?

Compare the finished wall to the maker’s rough-in reference, not to a guess about the handle gap. The logic from the makers’ pages is simple. If the valve is inside its rough-in range, no extension should be needed. If it is too deep but within what the exact kit adds, use that kit. If it is deeper than the kit covers, or the maker says no kit exists, the reliable repair is to reset the valve rather than stack mismatched extenders.

The reference point differs by maker, so use the numbers for your valve only:

• Delta: in an answer on its 17 Series extension kit page, Delta says the distance from the stringer to the front of the black plaster guard is 2-3/4 in. plus or minus 1/4 in., and that this is the same distance to the finished wall (Delta: RP77992 questions and answers).
• Moen Posi-Temp: Moen’s rough-in instructions show a range of 2-1/4 in. minimum to 3-1/2 in. maximum, with the plaster ground flush with the finished wall.
• Kohler Rite-Temp: trim specs commonly say to use a deep roughing-in kit when finished-wall depth is over 3-1/2 in. and up to 4-1/4 in., for the trim and valve contexts those specs list.
• Gerber Treysta: for standard wall construction, the instructions say the plaster guard should be flush with the interior finished wall.
• Symmons Temptrol: the spec sheet gives a rough-in of 2-3/8 in. plus or minus 1/2 in.

The research did not find base rough-in ranges for American Standard R110/R120 or Flash/TU valves, so do not borrow another brand’s number for them. Use the installation sheet for your specific rough-in valve.

Identify the Valve Family and the Trim Series

Identify two things: the valve in the wall and the trim on it. Choosing by brand alone, or even by rough-in body alone, is a common mistake. Delta says its R10000 extension-kit choice depends on the trim series. Moen’s FAQ picks by valve type, handle operation, trim family, finish and sometimes date. Kohler’s chart picks by trim design and valve family.

Some tells help:

• Moen: Posi-Temp rotates only and controls temperature. Moentrol pushes and pulls as well as rotating, and controls volume plus temperature. M-CORE U130/U140 uses lift-and-rotate operation and controls volume plus temperature.
• Delta: in an answer on its RP77991 page, Delta says the 14 Series cartridge that kit fits is RP46074, which has two flat sides on the stem, and that the 17 Series cartridge RP46463 also has flat sides on the stem and does not use that kit (Delta: RP77991 questions and answers). So do not pick a kit by the shape of the stem. Go by trim series or model number.
• Delta integrated diverters: the 24, 27 and 27T Series map to different integrated-diverter kits, so the R22000 rough-in alone is not enough.
• Gerber: Treysta is its own family. Gerber says Treysta cartridges look different from earlier ones and warns against installing a new Treysta cartridge in an old rough-in valve body.

For the wider hunt, see our guides to which shower trim kits fit your valve and to identifying a Delta, Moen, Kohler, Pfister, American Standard, Symmons, Grohe or Gerber shower valve.

Shower Valve Extension Kits: The Chart

Every row below comes from the maker’s own page or spec. The chart narrows the field. It is not a promise of fit, so confirm the part number on the maker’s page against your model and trim before ordering.

Maker	Valve family or trim context	Kit	Depth added	Watch for
Delta	13/14 Series tub/shower, current MultiChoice/R10000 trim	RP77991	Wall thickness up to 1-3/4 in.	Do not read this as “all 1400 Series”; confirm model and trim
Delta	17 Series tub/shower	RP77992	Wall thickness up to 1-3/4 in.	Separate from 17T
Delta	TempAssure 17T	RP75136	Check Delta’s current instruction sheet	17T only
Delta	3- and 6-setting separate diverter (R11000-T118 context)	RP75137	1 in.	Not the R22000 integrated-diverter family
Delta	MultiChoice integrated diverter, 24 Series, R22000	RP90542	1 in.; for wall thickness over 1-1/8 in. up to 2-1/8 in.	Integrated, not separate, diverter
Delta	MultiChoice integrated diverter, 27 Series, R22000	RP90543	1 in.	Delta makes no longer integrated-diverter extension
Delta	MultiChoice integrated diverter, 27T Series, R22000	RP90544	For wall thickness over 1-1/8 in. up to 2-1/8 in.	27T TempAssure only
Moen	Original single-handle valve (push/pull and rotate, introduced 1964)	10399 chrome, 99503 polished brass	1 in.	Not Posi-Temp, Moentrol or M-CORE
Moen	Moentrol	137347 or 193112	1 in.	193112 is for named trim families such as Flara, Doux, Arris, Weymouth and Align
Moen	Posi-Temp	96945, 96858 or 193114; 96955 or 96868 where 2 in. is allowed	1 in. or 2 in.	The 2 in. kit is not allowed for several named trims
Moen	M-CORE U130/U140	200755, 200779, 200780 or 200781	1 in.	Use Moen’s model-number list to pick
Kohler	Rite-Temp valves K-304, K-305, K-11748, K-306 and K-2971	Kit chosen by trim design	Some specs cover 3-1/2 in. to 4-1/4 in. finished-wall depth	Kohler says some kits are not interchangeable
Kohler	Rite-Temp K-8304 / K-8305 and K-28305 cartridge families	K-10350-NA	3/4 in.	Support page names K-8304; the spec says all trims for K-8305 and K-28305 cartridges
Pfister	Single-control tub/shower, non-SecurePfit trims	910-563A/K/U/Y	7/8 in.	Not for SecurePfit
American Standard	R110/R120 rough valves, single-control pressure-balance trim	M961818-0020A	3/4 in.	Not Flash/TU
American Standard	Flash rough-in valves with TU Series pressure-balance trim	M970649	3/4 in.	Includes two 4 in. screws plus a handle-adaptor screw
American Standard	R422/R433 diverter valves	963554	Maximum 3/4 in.	A diverter extension, not for a pressure-balance mixer
Symmons	Temptrol	TA-10-EXT-KIT	Depth not found	Spindle extension, longer handle screws, diverter/volume-control extension, longer escutcheon screws
Symmons	Safetymix / Visu-Temp	C-5-EXT-KIT	Depth not found	Listed for Safetymix and Visu-Temp shower series valves
Gerber	Treysta valves, with or without diverter	D113001 (and BB, BN, BS finishes)	Exact added depth not found on Gerber’s pages	Treysta only, not universal Danze/Gerber
Grohe	GrohSafe 3.0 pressure-balance trims, rough-ins 35 110 through 35 116	49121000	3/4 in.	35 114 is not sold in Canada

Three cautions on that chart. First, Moen’s M-CORE kit assignment is where its own pages disagree: the FAQ groups trims by family, while the separate model-number list places some Arris model numbers differently. So do not trust a trim-family name for M-CORE. Look up your exact model number in Moen’s M-CORE list.

Second, Delta’s RP75136 product page does not say how much depth the kit adds. Confirm against the current instruction sheet before ordering.

Third, Pfister also lists 970-0890 as a shower diverter extension kit for its 15 Series, but the page we reviewed did not state its added depth or contents.

If There Is No Kit for Your Valve

Sometimes the honest answer is that no kit fits. According to Delta’s RP75136 page, some units have no extension kit and require re-plumbing. Delta’s RP90543 page says it does not make a longer integrated-diverter extension when RP90543 is not enough.

Kohler says thermostatic trims do not offer deep roughing-in kits. They use short, medium and long K-joints included with the trim, and Kohler says there is no longer stem-extension option.

Moen says the 2 in. Posi-Temp kit is not an option for Doux, Flara, Colinet, 90 Degree, Bamboo, Felicity, Fina, Icon, Rothbury and Waterhill trims. Those use the named 1 in. path instead.

Be careful with Delta’s older valves. Delta’s pages say RP75136 will not work with a 144910-SS 1400 Series faucet and that Delta does not offer an extension for it. Yet RP77991 is described as fitting newer 1400 series valves. Both can be true if Delta uses the 1400 and 14 labels across different generations. So current 13/14 Series MultiChoice trims use RP77991, while some older 1400, ball-type or Foundation-style Delta units may have no kit and may need re-plumbing. One Delta page also says B112900C has no extension kit. Treat that as an edge case, not a rule for other Delta models.

The research found no maker statement that current Pfister, American Standard, Symmons, Gerber or Grohe single-handle families have no extension kit. That is “not found,” not “does not exist.”

When the exact kit is not enough, or the extension would change how the handle connects, the durable answer is to open the wall and reset the valve. If the valve is inside the wall and you are unsure, call a plumber before cutting. According to Moen’s Posi-Temp installation sheet, pressure-test and flush before closing the wall opening, and do not turn on the supplies before the instructions call for it, because debris can damage cartridge sealing surfaces or block the balancing spool.

The Opposite Fault: The Valve Sticks Out Too Far

A deep rough-in kit will not pull a valve backward. Delta’s answer for a valve outside the finished-wall dimensions in the outward direction is that a valve sticking out too far needs to be reinstalled.

Some makers do list separate shallow or thin-wall parts. Kohler’s Honesty spec warns that long trim screws can damage K-2971-KS in thin-wall situations and points to thin-wall kit 88526 where needed. A Gerber Treysta FAQ, seen on a mirror site, lists shallow-depth kit GA663B11/BB/BN/BS for all collections except Vaughn, Avian and Lemora, with shallow defined as 2-3/4 in. to 3 in. from the back of the valve body to the front of the plaster guard. For Moen, Pfister, American Standard, Symmons and Grohe, the research found no maker-named shallow-wall part. Use a maker-specified part where one exists, or reset the valve.

Aftermarket Kits and Stem Extenders

Retailer listings and “compatible with” kits show what exists in the field, but they should not override the maker’s fitment rules. One example is Kibi, which lists its own extension kit for Kibi models KSF403, KSF404, KSF405, KSF406, KSF408, KSF409, KSF412 and KSF413, with up to 7/8 in. of outward extension. It is not a cross-brand kit.

Danco sells a brass stem extension kit for Price Pfister faucets. Its listing says the kit provides additional length for tub and shower stems.

Two-handle and three-handle valves are a different category. They use stem extenders rather than the trim-family kits above. Pfister, for example, lists a Stem Extension Kit 910-005.

Follow the Manufacturer’s Sequence

Installation steps differ enough between makers that a generic “add a stem extender” instruction would mislead. Professional opinions vary on how to tackle a deep valve, so follow the sheet that comes with your exact kit.

What to Do Next

Measure the gap, find your valve family and trim series, and match them to the chart. If the maker lists no kit, or the kit is not enough, plan to reset the valve. For the wider picture, see our shower repair hub.

Sources

• Delta: RP77991 Extension Kit
• Delta: RP77992 Extension Kit
• Delta: RP75136 Extension Kit
• Delta: RP75137 Extension Kit
• Delta: RP90542 Extension Kit
• Delta: RP90543 Extension Kit
• Delta: RP90544 Extension Kit
• Delta: R22000-WS
• Delta: RP77991 questions and answers
• Delta: RP77992 questions and answers
• Moen: Rough-in valve installed too far back, extension kit FAQ
• Moen: M-CORE Shower Extension Kit List by Model Number
• Moen: INS1997 instruction sheet
• Moen: Posi-Temp installation sheet (INS1986)
• Kohler: Deep Roughing-In Kits for Rite-Temp Valve Trim
• Kohler: Extension and Deep Roughing-In Kits for Faucets
• Kohler: K-10350 spec
• Kohler: Refina spec
• Kohler: Honesty spec
• Pfister: 910-563 spec
• Pfister: 970-0890 Shower Diverter Extension Kit
• Pfister: 910-005 spec
• American Standard: M961818 Deep Rough-In Kit
• American Standard: M970649 Deep Rough-In Kit
• American Standard: 963554 Diverter Extension Kit
• Symmons: Temptrol repair parts
• Symmons: C-5-EXT-KIT
• Symmons: Temptrol spec sheet
• Gerber: Treysta compatibility
• Gerber: Treysta installation instructions
• Gerber: Treysta FAQ mirror
• Grohe: 49121000 GrohSafe 3.0 Extension Kit
• Kibi: Shower Valve Extension Kit
• Danco: Brass Stem Extension Kit for Price Pfister Faucets
• Danco: 2016 catalog

Educational content only. Not a substitute for licensed professional advice. Local plumbing codes vary by jurisdiction. Use of any guidance from this guide is at your own risk.