Shower Valve Hole Size: Moen, Delta, Kohler, Diamond Cores

Every hole through finished tile has two numbers. The smallest hole clears whatever passes through it. The largest hole is the biggest one the trim plate, flange or escutcheon still hides. Any bit between those two numbers is the right bit. We call that range the hole window, and this chart gives you the window for every fixture on a bathroom wall, from the maker's own install sheet, plus the diamond core that lands in it.

It's written for the people who drill these holes every week: tile setters, plumbers doing trim-out, and shower glass crews. If you're drilling one hole in your own bathroom, the numbers are the same.

Tap a wall and a fixture in the drawing above to see its window and bit. Every number it shows is in the tables below.

What size hole do I drill for a shower valve?

Shower valve hole size is printed in the valve's rough-in instructions, and it changes with the wall. Moen, for one, gives two sizes for the same Posi-Temp valve: 4-1/2 in. through a tile wall and 2-1/4 to 3-1/2 in. through a fiberglass surround under 1/4 in. thick. Here is what each maker's sheet says.

Valve	Tile wall (thick)	Fiberglass wall (thin)	Trim plate	Source
Moen Posi-Temp	4-1/2 in., the size of the plaster ground	2-1/4 to 3-1/2 in. (wall under 1/4 in.)	7 in. escutcheon (T2133 series)	Moen INS2153D, fig. 3.1 and 3.2; Moen T2133 spec, rev. 4/17
Moen M-CORE	4-1/4 in., the size of the plaster ground (wall 1/4 to 1 in.)	3-3/4 in. (wall under 1/4 in.)	Varies by trim	Moen INS10923, pp. 4–5
Symmons Temptrol (C-96-1)	4 in. minimum, 4-1/2 in. maximum	Same	Varies by trim	Symmons ZV-459, fig. 1
Symmons S-262 / 46-2 body	3-1/2 in. minimum, 4 in. maximum	Same	Varies by trim	Symmons ZV-3246
Kohler Rite-Temp (K-8304)	4 in. on walls under 3/4 in.; 5 in. on walls over 3/4 in.	4 in.	Varies by trim	Kohler K-8304-K spec, p. 3
Delta MultiChoice (R10000)	4 x 4 in. square, the size of the plaster guard	Same	6-1/2 to 7 in., by collection	Delta DSP-B-R10000, rev. K
Grohe	Sized by model; read the rough-in sheet	Same	Varies by trim	Grohe rough-in instructions

Two things trip people up on shower valve hole size. First, the 2-1/4 to 3-1/2 in. number you'll see quoted for Moen is the fiberglass size. In tile, Moen says to drill a 4-1/2 in. hole, the same size as the plastic plaster ground on the valve, and to take the ground off only after the valve is set. Second, Delta's plaster guard is square, not round. A 4 in. round core can't clear the guard's corners, so cut the square with a PL-45 4-1/2 in. V-groove diamond blade ($38.53) on an angle grinder.

ITM's White Diamond tile bits stop at 2-1/2 in. For a 3 or 4 in. valve hole in porcelain, use an ITM stone countertop core: GRA-15 (3 in., $128.97) or GRA-18 (4 in., $155.65). Both thread onto an angle grinder, cut dry and cut 2-1/2 in. deep. GRA-18 lands right in the Symmons C-96-1 and Kohler Rite-Temp windows.

We don't sell a 4-1/2 in. porcelain core. For a Moen Posi-Temp hole in porcelain, core 4 in. with GRA-18, then open it to your pencil line with a DMC-75 diamond end mill ($96.23). Our diamond end mill guide shows how to mill to a line without chipping. In glazed ceramic, the CG0072 carbide grit hole saw cuts 4-1/2 in. in one pass ($113.36).

How big can the hole be before the trim won't cover it?

A hole can be as big as the trim plate still covers with some overlap left on every side. The plate has to sit flat on tile all the way around, or water gets behind it. That top limit is the window's largest hole.

The smallest hole is set by the gap the tile needs around a pipe. Tile can't touch the pipe, or movement in the pipe cracks it. The tile industry's movement-joint standard (TCNA EJ171) puts joints at pipes and asks for 1/4 in. where you can get it and never less than 1/8 in. Fill the gap with a flexible sealant that meets ASTM C920, such as 100% silicone, not grout. CTEF's Scott Carothers summed up the rule in NTCA's TileLetter in 2023.

So the hole for a pipe is its outside diameter plus 1/4 in. (1/8 in. a side) at the least, and plus 1/2 in. (1/4 in. a side) when the trim covers it. A 1/2 in. threaded nipple is 0.840 in. across. The smallest hole is 1-1/8 in., and the preferred hole is 1-3/8 in.

Measure the pipe, not its name. Copper tube is always 1/8 in. bigger than its size: 1/2 in. copper is 0.625 in. across (Copper Development Association). A 1/2 in. threaded nipple is 0.840 in. (ASME B36.10M). A 1-1/2 in. PVC or ABS drain is 1.900 in., and 2 in. is 2.375 in. (Charlotte Pipe, ASTM D2665).

What size hole for a shower arm, tub spout or steam head?

A shower arm, a threaded tub spout and a hand shower elbow all come out of the wall on a 1/2 in. threaded nipple, so each needs a 1-1/8 in. hole at the least. A slip-on tub spout slides onto 1/2 in. copper, which needs 7/8 in. Delta's spout sheet names both: "Slip Fit 1/2" CWT" and "Threaded 1/2" or 3/4" IPS".

The 7/8 in. hole you'll see recommended for every spout is too tight for a threaded one. It leaves 0.018 in. a side around a 0.840 in. nipple, and the tile will touch the pipe.

Steam heads have their own sizes. ThermaSol's TSS head says "Drill a 1-1/4" diameter hole in the shower wall," and the SteamVection head says 1-1/8 in. MrSteam's AromaSteam head needs "a 1.5" clearance hole around the steam pipe."

What comes through the tile	Outside diameter	Smallest hole	Porcelain pick	Glazed ceramic pick
Shower arm, threaded tub spout, hand shower elbow (1/2 in. threaded nipple)	0.840 in.	1-1/8 in.	ANG-30, $23.47 each (min. 2)	ANG-30, $23.47 each (min. 2)
Slip-on tub spout (1/2 in. copper)	0.625 in.	7/8 in.	HEX-26, $18.53 each (min. 2)	HEX-26, $18.53 each (min. 2)
ThermaSol TSS steam head	Maker's size	1-1/4 in.	ANG-32, $26.83 each (min. 2)	ANG-32, $26.83 each (min. 2)
ThermaSol SteamVection head	Maker's size	1-1/8 in.	ANG-30, $23.47 each (min. 2)	ANG-30, $23.47 each (min. 2)

Store prices on November 12, 2026. Our guide to drilling through tile covers the drilling itself: the 45° start, no hammer mode, and light pressure.

What size hole do grab bar anchors need in tile?

A grab bar hole is the size the anchor's instructions give, and it ranges from 1/4 in. for a screw into blocking to 1-1/4 in. for hollow-wall anchors. Size the hole to the anchor, not to the screw.

How the bar is held	Hole through the tile	Bit	Source
Screws into a stud or blocking	1/4 in. through the tile, then a 1/8 in. pilot into the wood	HEX-14, $15.22 each (min. 4), then a VT-1 countersink, $13.64 each (min. 4)	Moen INS10780 (pilot). The 1/4 in. tile hole is our clearance for a #10 screw.
Moen SecureMount anchor	1-1/4 in. at each mount	ANG-32, $26.83 each (min. 2)	Moen SMA1002CH spec
WingIts GBW40 / GBW50	1-1/4 in. at each flange	ANG-32, $26.83 each (min. 2)	WingIts install guide
WingIts Residential RESGBW35	Two 3/4 in. holes at each flange	HEX-24, $18.22 each (min. 2)	WingIts RESGBW35 guide, p. 2

Moen Home Care grab bar flanges are 3.15 in. across, so a 1-1/4 in. hole hides under the flange with room to spare. You'll see SnapToggle anchors suggested for grab bars. Toggler lists them for handrails, not grab bars, so we leave them to towel bars: a SnapToggle BA or BB takes a 1/2 in. hole (HEX-20, $16.97 each, min. 4).

For the screw holes themselves, many crews already carry V-Groove bits. Our V-Groove guide covers those. For shower doors and hinges, see frameless shower door installation.

What is the standard faucet hole size?

The standard faucet hole is 1-3/8 in. It fits every maker's range we checked: Kohler's K-7514 asks for 1-1/4 to 1-1/2 in., and Moen's 87446 asks for at least 1-1/4 in. Moen's Kivo is the exception, at 1-1/2 in. minimum, so check the sheet for your model.

Dishwasher air gaps take 1-3/8 in. too: Air Gap International's sheet says "Unit installation requires a 1-3/8 inch hole," and Kraus's KAG guide says the same. Delta's RP50781 soap dispenser needs 1-3/8 in., per Delta's answer on its product page.

The bit depends on what you're drilling. A porcelain-slab or tile vanity top takes ANG-34 (1-3/8 in., $29.34 each, min. 2). A granite or marble top takes GRA-11 (1-3/8 in., $69.81). The reason is depth: White Diamond bits cut 1-1/4 in. deep, and a 3 cm stone top is 1-3/16 in. thick, which leaves 1/16 in. to spare and none if there's a subtop under it. GRA cores cut 2-1/2 in. deep. Finish the top edge with a POINT-1 diamond countersink ($50.21) so the faucet base sits on a smooth bevel.

ITM rates its stone cores for granite, marble, stone and porcelain. It doesn't list quartz. If you're drilling a quartz top, call us before you buy. Dry-cutting stone and quartz throws off crystalline silica, so use a shroud and a HEPA extractor; our quartz ban explainer covers why that matters now.

Diamond core sizes: every tile and stone bit we carry

We carry diamond and carbide grit bits for tile and stone from 3/16 in. to 5 in. This table puts every size on one line, so you can see which families make it and what it costs.

Size (in.)	White Diamond hex (impact or drill)	Blu Diamond (1/2 in. drill, wet)	White Diamond grinder	Stone core (grinder, dry)	Carbide grit (drill + arbor)
3/16	$15.22 (min. 4)	—	—	—	—
1/4	$15.22 (min. 4)	$22.15 (min. 2)	—	—	—
5/16	$15.65 (min. 4)	$23.93 (min. 2)	—	—	—
3/8	$15.65 (min. 4)	$24.46 (min. 2)	—	—	—
1/2	$16.97 (min. 4)	$30.65 (min. 2)	—	—	—
5/8	$17.30 (min. 4)	—	—	—	—
3/4	$18.22 (min. 2)	$32.22 (min. 2)	—	—	$31.15
7/8	$18.53 (min. 2)	—	$18.84 (min. 2)	—	$31.15
1	$20.50 (min. 2)	$34.33 (min. 2)	$20.96 (min. 2)	$57.12	$34.01
1-1/8	—	—	$23.47 (min. 2)	—	$34.01
1-1/4	—	—	$26.83 (min. 2)	$65.05	$34.90
1-3/8	—	—	$29.34 (min. 2)	$69.81	$35.19
1-1/2	—	—	$31.86 (min. 2)	$76.16	$35.19
2	—	—	$41.92	$100.96	$43.17
2-1/8	—	—	—	—	$51.07
2-1/4	—	—	—	—	$51.07
2-1/2	—	—	$52.82	—	$57.58
2-3/4	—	—	—	—	$57.58
3	—	—	—	$128.97	$69.76
3-1/2	—	—	—	—	$74.08
4	—	—	—	$155.65	$91.98
4-1/2	—	—	—	—	$113.36
5	—	—	—	—	$129.80

Prices are per bit, store prices on November 12, 2026. Where a minimum is shown, that's the fewest you can order. A dash means that family doesn't make the size.

How to read this chart: each line is one bit family. Find a hole size along the bottom and read the price per bit up the side.

What it means for you: up to 1 in., the hex White Diamond bits are the cheapest way through porcelain. Above 2-1/2 in., porcelain needs a stone core at $128.97 (3 in.) or $155.65 (4 in.), while glazed ceramic can use a carbide grit saw at $69.76 or $91.98.

Which diamond core fits my impact, drill or grinder?

The tool in your hand narrows the choice before the tile does. Hex-shank White Diamond bits go in an impact driver or drill. Blu Diamond bits need a 1/2 in. drill and water. Threaded bits go on an angle grinder.

Family	Shank	Runs in	Rated for	Cut depth	Water	Source
White Diamond hex	1/4 in. hex	Impact driver or drill	Porcelain, ceramic, granite, marble	1-1/4 in.	Dry	ITM 2026 catalog, p. 76
Blu Diamond	3/8 in. shank	1/2 in. drill, rotation only	Porcelain, ceramic	—	Wet: ITM says "use water"	ITM 2026 catalog, p. 78
White Diamond grinder	5/8"-11 thread	Angle grinder	Porcelain, ceramic, granite, marble	1-1/4 in.	Dry	ITM 2026 catalog, p. 76
Stone core	5/8"-11 thread	Angle grinder	Granite, marble, stone, porcelain	2-1/2 in.	Dry only	ITM 2026 catalog, p. 94
Carbide grit	Arbor: ARB-2 to 1-3/16 in., ARB-5 from 1-1/4 in.	Drill	Ceramics, fiberglass, cast iron, hardwood, composites. Not porcelain.	1-3/8 in.	—	Carbide grit spec sheet

Safety: drilling porcelain, stone and quartz dry throws off respirable crystalline silica. OSHA's silica rule for construction (29 CFR 1926.1153) requires controlling that dust: use a shroud with a HEPA dust extractor, or water where the bit is made for it, and follow your company's exposure control plan. Wear eye protection, and check behind the wall for pipe and wire before you core.

Keep the hammer off for all of them. ITM lists its PAD-5811 adapter ($12.81, min. 4) for running threaded mills, countersinks and hole saws in a 1/2 in. drill. It doesn't list it for the grinder tile bits, so we don't recommend that pairing.

For a fiberglass tub surround, use carbide grit, not diamond. A Moen Posi-Temp valve through fiberglass lands in the 2-1/4 to 3-1/2 in. window, and CG0040 (2-1/2 in., $57.58) is the size that fits it.

The hole window chart: every fixture, smallest to largest hole

This is the whole bathroom on one table. "Smallest hole" clears the pipe by 1/8 in. a side, or is the maker's printed size. "Largest hole" is the maker's maximum, or the trim plate's size where the maker gives none. The picks are the bit of ours that lands in the window for each material: porcelain or stone, glazed ceramic, and fiberglass (carbide grit, not diamond).

Fixture	Wall	Passes through	OD (in.)	Smallest hole	Largest hole	Porcelain or stone	Glazed ceramic	Fiberglass	Source
Moen Posi-Temp valve, tile wall	Shower wall	4-1/2 in. plaster ground	—	4-1/2	4-1/2	None. Core 4 in. with GRA-18, mill with DMC-75	CG0072 4-1/2 in., $113.36	— (tile wall row)	Moen INS2153D, fig. 3.2
Moen Posi-Temp valve, fiberglass	Shower wall	Valve body, wall under 1/4 in.	—	2-1/4	3-1/2	—	—	CG0040 2-1/2 in., $57.58	Moen INS2153D, fig. 3.1
Moen M-CORE valve, tile wall	Shower wall	4-1/4 in. plaster ground	—	4-1/4	4-1/4	None. Core 4 in. with GRA-18, mill with DMC-75	None	— (tile wall row)	Moen INS10923, p. 4
Moen M-CORE valve, fiberglass	Shower wall	Valve body, wall under 1/4 in.	—	3-3/4	3-3/4	—	—	None. Our nearest, CG0064 (4 in.), is 1/4 in. over	Moen INS10923, p. 5
Symmons Temptrol C-96-1 valve	Shower wall	Valve body	—	4	4-1/2	GRA-18 4 in., $155.65	CG0064 4 in., $91.98	CG0064 4 in., $91.98	Symmons ZV-459, fig. 1
Symmons S-262 / 46-2 valve body	Shower wall	Valve body	—	3-1/2	4	GRA-18 4 in., $155.65	CG0056 3-1/2 in., $74.08	CG0056 3-1/2 in., $74.08	Symmons ZV-3246
Kohler Rite-Temp valve, wall under 3/4 in.	Shower wall	Valve body	—	4	4-1/2	GRA-18 4 in., $155.65	CG0064 4 in., $91.98	CG0064 4 in., $91.98	Kohler K-8304-K, p. 3
Kohler Rite-Temp valve, wall over 3/4 in.	Shower wall	Valve body	—	5	5	None	CG0080 5 in., $129.80	— (fiberglass walls are under 3/4 in.)	Kohler K-8304-K, p. 3
Delta MultiChoice R10000 valve	Shower wall	4 x 4 in. square plaster guard	—	Square	Square	Not a core. PL-45 blade, $38.53	Not a core. PL-45 blade, $38.53	Not a core	Delta DSP-B-R10000, rev. K
Shower arm	Shower wall	1/2 in. threaded nipple	0.840	1-1/8	Trim size	ANG-30 1-1/8 in., $23.47 (min. 2)	ANG-30 1-1/8 in., $23.47 (min. 2)	CG0018 1-1/8 in., $34.01	ASME B36.10M
Hand shower elbow	Shower wall	1/2 in. threaded nipple	0.840	1-1/8	Trim size	ANG-30 1-1/8 in., $23.47 (min. 2)	ANG-30 1-1/8 in., $23.47 (min. 2)	CG0018 1-1/8 in., $34.01	ASME B36.10M
Steam head, ThermaSol TSS	Shower wall	Steam head	—	1-1/4	1-1/4	ANG-32 1-1/4 in., $26.83 (min. 2)	ANG-32 1-1/4 in., $26.83 (min. 2)	CG0020 1-1/4 in., $34.90	ThermaSol TSS install sheet
Tub spout, threaded	Tub wall	1/2 in. threaded nipple	0.840	1-1/8	Trim size	ANG-30 1-1/8 in., $23.47 (min. 2)	ANG-30 1-1/8 in., $23.47 (min. 2)	CG0018 1-1/8 in., $34.01	Delta DSP-B-U1010-PK
Tub spout, slip-on	Tub wall	1/2 in. copper	0.625	7/8	Trim size	HEX-26 7/8 in., $18.53 (min. 2)	HEX-26 7/8 in., $18.53 (min. 2)	CG0014 7/8 in., $31.15	Delta DSP-B-U1010-PK
Single-hole faucet	Vanity and counter	Faucet shank	—	1-1/4	1-1/2	Porcelain: ANG-34 1-3/8 in., $29.34 (min. 2). Granite or marble top: GRA-11 1-3/8 in., $69.81	ANG-34 1-3/8 in., $29.34 (min. 2)	CG0022 1-3/8 in., $35.19	Kohler K-7514; Moen 87446
Dishwasher air gap	Vanity and counter	Air gap body	—	1-3/8	1-3/8	Porcelain: ANG-34 1-3/8 in., $29.34 (min. 2). Granite or marble top: GRA-11 1-3/8 in., $69.81	ANG-34 1-3/8 in., $29.34 (min. 2)	CG0022 1-3/8 in., $35.19	Air Gap International; Kraus KAG
Soap dispenser	Vanity and counter	Dispenser shank	—	1-3/8	1-3/8	ANG-34 1-3/8 in., $29.34 (min. 2)	ANG-34 1-3/8 in., $29.34 (min. 2)	CG0022 1-3/8 in., $35.19	Delta RP50781 product page
Sink or toilet supply stub	Vanity and counter	1/2 in. copper or PEX	0.625	7/8	Trim size	HEX-26 7/8 in., $18.53 (min. 2)	HEX-26 7/8 in., $18.53 (min. 2)	CG0014 7/8 in., $31.15	Copper Development Association
3/4 in. supply	Vanity and counter	3/4 in. copper or PEX	0.875	1-1/8	Trim size	ANG-30 1-1/8 in., $23.47 (min. 2)	ANG-30 1-1/8 in., $23.47 (min. 2)	CG0018 1-1/8 in., $34.01	Copper Development Association
Sink drain arm	Vanity and counter	1-1/2 in. PVC or ABS	1.900	2-1/4	Trim size	ANG-40 2-1/2 in., $52.82	CG0036 2-1/4 in., $51.07	CG0036 2-1/4 in., $51.07	Charlotte Pipe (ASTM D2665)
2 in. drain	Vanity and counter	2 in. PVC or ABS	2.375	2-3/4	Trim size	GRA-15 3 in., $128.97, if the trim covers 3 in.	CG0044 2-3/4 in., $57.58	CG0044 2-3/4 in., $57.58	Charlotte Pipe (ASTM D2665)
Toilet flange	Toilet and floor	4 in. PVC	4.500	—	—	Not a core. Cut the tile to the flange before you set it.	Not a core	Not a core	Charlotte Pipe (ASTM D2665)
Grab bar screw into blocking	Grab bars	#10 screw	—	1/4	5/16	HEX-14 1/4 in., $15.22 (min. 4)	HEX-14 1/4 in., $15.22 (min. 4)	—	Moen INS10780 (1/8 in. pilot); tile hole is our clearance
Grab bar, Moen SecureMount	Grab bars	Anchor	—	1-1/4	1-1/4	ANG-32 1-1/4 in., $26.83 (min. 2)	ANG-32 1-1/4 in., $26.83 (min. 2)	CG0020 1-1/4 in., $34.90	Moen SMA1002CH
Grab bar, WingIts GBW40 / GBW50	Grab bars	Anchor	—	1-1/4	1-1/4	ANG-32 1-1/4 in., $26.83 (min. 2)	ANG-32 1-1/4 in., $26.83 (min. 2)	CG0020 1-1/4 in., $34.90	WingIts install guide
Grab bar, WingIts RESGBW35	Grab bars	Two anchors per flange	—	3/4	3/4	HEX-24 3/4 in., $18.22 (min. 2)	HEX-24 3/4 in., $18.22 (min. 2)	CG0012 3/4 in., $31.15	WingIts RESGBW35 guide, p. 2

The tool above slides any fixture's window along a ruler of every bit we carry, filtered by your material and tool. Choose "Your own" and type your pipe and trim plate sizes for a fixture that isn't listed.

Which holes can't a core cut?

Some bathroom openings are bigger than any core, or not round. Cut these with a blade before or after the tile goes in.

• Toilet flange. A 4 in. PVC drain is 4.500 in. across, and the closet flange on it is wider still. Cut the floor tile to fit around it with a grinder before you set the tile.

• Floor-mount tub filler. Kohler's drawings show a 4-3/4 to 5 in. base. The floor opening comes from the mounting-block rough-in sheet, so read that sheet before you cut.

• Delta's square plaster guard. Cut the 4 x 4 in. square with a PL-45 V-groove blade.

• Moen M-CORE and Posi-Temp in porcelain. 4-1/4 and 4-1/2 in. are bigger than our largest porcelain core. Core 4 in., then mill to the line.

What does a trim-out kit cost?

A tub-shower bath in porcelain with a Symmons C-96-1 valve takes four bit sizes. That's GRA-18 for the valve ($155.65), ANG-30 for the arm and spout (2 at $23.47), HEX-26 for the toilet stop (2 at $18.53), and HEX-14 for 12 grab bar screws (4 at $15.22). Add 4 VT-1 countersinks ($13.64 each) for the screw holes. The total is $355.09 at store prices on November 12, 2026, minimums included.

The bits outlast the job. The 4 in. core is one per crew. The 1-1/8 in. bit wears fastest, since every arm and spout uses it.

The kit builder above counts the holes on your job and returns the bits, minimums and total. A first order of tile or glass bits ships free with a matching diamond countersink; see the First Pack offer.

"Read the rough-in sheet before you pick up the bit. The same Moen valve wants 2-1/4 inches through a fiberglass surround and 4-1/2 through tile. Drill the smallest size that clears it, so the trim still covers the hole the next time somebody opens that wall."

David Castro, President, Eldorado Tools

Shower valve and fixture hole questions

What size hole saw for a Moen shower valve?

In a tile wall, 4-1/2 in. for a Posi-Temp and 4-1/4 in. for an M-CORE, the size of each valve's plaster ground. Through a fiberglass surround under 1/4 in. thick, Posi-Temp takes 2-1/4 to 3-1/2 in. and M-CORE takes 3-3/4 in.

What size hole for a Delta shower valve?

Delta's MultiChoice R10000 rough-in has a square 4 x 4 in. plaster guard, and the cutout follows it. Cut a square, not a round hole.

Is there a standard shower valve hole size?

No. Each maker sets its own shower valve hole size. In a tile wall, 4 to 4-1/2 in. covers Moen, Symmons and Kohler, and Delta's MultiChoice cutout is a 4 x 4 in. square.

Are shower valves 1/2 or 3/4 in.?

That's the pipe connection, and your valve's sheet lists it. It doesn't change the hole through the tile. The valve body and its plaster ground set the hole.

Do diamond tile bits need water?

It depends on the bit. ITM's White Diamond bits are made to cut dry. Blu Diamond bits are wet bits: ITM says "use water." The GRA stone cores are dry only.

What size hole for a WingIts anchor?

The standard WingIts GBW40 and GBW50 take a 1-1/4 in. hole at each flange. The Residential RESGBW35 takes two 3/4 in. holes at each flange.

How do I make a valve hole bigger after the tile is set?

Mill it to a pencil line with a diamond end mill, such as a DMC-75, using light sideways pressure. Our diamond end mill guide walks through it.

Written by Vanessa at Eldorado Tools from the makers' own sheets: Moen INS2153D, INS10923, INS10780, SMA1002CH and T2133; Symmons ZV-459 and ZV-3246; Kohler K-8304-K and K-7514; Delta DSP-B-R10000 and DSP-B-U1010-PK; ThermaSol, MrSteam, WingIts, Toggler, Air Gap International and Kraus install guides; the ITM 2026 catalog (pp. 76–78, 94); Charlotte Pipe; the Copper Development Association; and TCNA EJ171 as reported in NTCA's TileLetter (2023). Prices are store prices of November 12, 2026. Change log: first published [date].