Problem solving
Drawer hits the pipes under the sink? Seven situations and the fix for each
You measured the cabinet, the drawer box arrived or the old one came out, and the back of the box hits the P trap, a shutoff valve or the disposal. This page is for the homeowner or cabinet shop with pipes in the way of a drawer: what each situation looks like, the one measurement that settles it, and the drawer that clears it.
Quick answer. A drawer hits the plumbing under a sink because a plain box is a closed rectangle and the trap sits inside its footprint. The fix is rarely moving the pipes; it is a pipe chase drawer, a box with a full height notch open at the back, sized and placed to the pipes by three numbers. Measure the left and right edges of the plumbing from the left cabinet side and the distance from the box front line to the frontmost pipe, keep at least 3 in of drawer on each side of the notch and in front of it, and the box slides home around the trap.
Ready to build it? The configurator prices every choice live and draws your box in 3D before you order.
1. The P trap is in the way
Size the notch to the trap. The P trap hangs below the bowl in the middle of the cabinet, exactly where the back of a plain box wants to be, which is why it stops nearly every rectangular drawer. A notch open at the back lets the trap sit inside the box when the drawer is closed and leave through the back when it opens.
Three measurements settle it. From the left cabinet side, measure to the left edge and the right edge of everything that passes through the box: tailpiece, trap and trap arm. From the box front line, the front edge of the cabinet sides in a frameless cabinet or the back of the face frame, measure straight back to the front of the trap. The notch width is that span plus about 1 in of room on each side, our suggestion rather than a rule, so a 7 in trap becomes a 9 in notch. The distance from the front to the notch is the distance to the trap minus about 1 in, never under 3 in: a trap 10 in back gives a 9 in front section, and on a 21 in box the notch reaches 12 in into the box. The pipe chase drawer page defines the terms, and how to measure plumbing for a U shaped drawer has the full method.
2. The drain is off center
Move the notch, not the drain. The notch center is a number you choose, from 4 1/2 to 31 1/2 in from the left outside edge of the box, so an off center drain just gives two legs of different widths. Take the midpoint of the plumbing’s left and right edges, measured from the left cabinet side, and subtract the slide clearance on the left: 1/2 in for side mount slides, 13/64 in for Blum TANDEM 563 with 5/8 in sides, half the width deduction for other undermount runners.
Then check the legs. The left leg is the distance to notch center minus half the notch width; the right leg is the box width minus both. Each must be at least 3 in. On a 33 in frameless base with side mount slides the box is 30 7/16 in wide; a trap spanning 18 to 25 in off the left side has its center at 21 1/2 in, so the distance to notch center is 20 31/32 in, and a 9 in notch leaves legs of 16 15/32 and 4 31/32 in. Both pass. A trap within about 3 1/2 in of a cabinet side leaves no room for a leg even with no clearance around it; the preview shows a red warning, and a roll out tray on the open side is the usual answer.
3. The drain is close to the front
Start the notch closer to the front. The notch can begin 3 in from the front outside face of the box, so a trap whose front edge sits 4 in or more behind the box front line still works with our suggested 1 in of room; the front section simply gets short, and a 3 to 5 in front section is a shelf for sponges rather than bottles. The notch depth grows as the front section shrinks, which costs nothing.
If the trap is closer than 3 in to the box front line, a notched box is out, and the answer is a lower plain box that passes under the trap. Measure from the cabinet floor to the bottom of the trap, take off about 1 in of room and the clearance the slide needs under the box, 9/16 in for Blum TANDEM 563 per Blum, and that is the tallest box. Nothing passes through it, so it is an ordinary custom drawer box with a drawer front; below 2 in of height, go to a roll out tray or a tip out.
4. Shutoff valves sit over a leg
Pick one of three fixes: a lower box, a wider notch, or a shorter slide. Supply stops usually sit near the back wall on each side of the drain, which puts them over the back of one or both legs, and the notch only clears what is inside it.
Measure two things: the height from the cabinet floor to the lowest point of each valve, and how far each valve sits from the back wall. A lower box keeps its top about 1 in below the valve, our suggestion, after the slide’s clearance under the box. A wider notch takes in a valve that sits close to the drain, as long as each leg stays at least 3 in. An 18 in slide instead of 21 in stops the legs 3 in further forward, so valves within 3 in of the back wall sit behind the box; Blum lists 18 29/32 in of inside depth for an 18 in TANDEM 563 runner. Moving the stops up the wall is the cleanest fix when a plumber is coming anyway, but it is their job.
5. A garbage disposal hangs into the drawer
Size the notch to the disposal body, not the trap, whenever the disposal hangs into the box height. A disposal hangs roughly 10 to 15 in below the sink flange and its body is about 6 to 9 in across, so in many sink bases its bottom sits below the top of a tall drawer. Measure from the cabinet floor to the bottom of the disposal and compare it with your planned box top. Above the box, only the pipes below the disposal pass through the notch. Below it, the notch widens to the disposal body plus about 1 in each side, and the distance from the front moves to the front of the body. The cord, the air switch hose and the dishwasher drain hose need a path too. Our U shaped drawer with a garbage disposal page covers all of it, including a double bowl sink with the disposal on one side.
6. The plumbing fills the cabinet
Split the space instead of fighting it. When a filter, a hot water tank, a disposal and a dishwasher hose all live in one sink base, a single tall U box often cannot clear everything. Three layouts work. Two stacked U shaped drawers: a deep lower box notched around the trap and a shallow upper box, 3 to 4 in tall, notched wider around the trap and disposal, each ordered separately with its own three numbers. A roll out tray behind the doors, low enough to pass under most of it. Or a tip out tray in the false front for the sponges with a half width tray or shelf below. Two U shaped drawers in a sink base works the heights out, and sink base storage options compares the layouts.
7. A pipe comes up through the cabinet floor
A rear notch clears a floor pipe the same way it clears a wall drain, as long as the pipe sits at least 3 in behind the box front line and at least 3 in from each side: the notch starts in front of the pipe and runs to the open back. What a notch open at the back cannot do is leave drawer behind the pipe or wrap it on four sides, because a drawer with a closed hole cannot pull out past a vertical pipe at all. If the pipe sits closer than 3 in to the front, or you want the space behind it, order a shallower plain custom drawer box whose depth stops about 1 in short of the pipe, or send the layout through the instant quote and we draw it with you. A second pipe elsewhere in the cabinet means two notches, which is also a quote.
Decision table
Symptom, measurement, fix and the field it goes in
Open the doors, find your symptom, take the one measurement, and the last column names the configurator field it goes into.
| Symptom | Measurement to take | The fix | Configurator field |
|---|---|---|---|
| DRAWER HITS THE P TRAP | Left and right edges of the trap from the left cabinet side; box front line to the front of the trap | Notch sized to the trap plus about 1 in each side | “Notch width (inches)” and “Distance from the front to the notch (inches)” |
| DRAIN IS OFF CENTER | Midpoint of the plumbing’s edges, minus the slide clearance on the left | Notch center moved; legs come out unequal, each at least 3 in | “Distance to notch center (inches, from the left outside edge)” |
| DRAIN IS CLOSE TO THE FRONT | Box front line to the front of the trap | Notch starts closer to the front, never under 3 in; closer than that, a lower plain box under the trap | “Distance from the front to the notch (inches)”, or “Height (Inches)” on a custom drawer box |
| SHUTOFF VALVES OVER A LEG | Floor to the lowest valve; valve to the back wall | Lower box, wider notch, or an 18 in slide so the legs stop short | “Height (Inches)”, “Notch width (inches)” or “Depth Selection” |
| DISPOSAL HANGS INTO THE BOX | Floor to the bottom of the disposal; width of the body | Notch sized to the body, or a lower box under it | “Notch width (inches)”, “Height (Inches)” and “Plumbing notes (optional)” |
| PLUMBING FILLS THE CABINET | Clear height under the lowest item over each leg; which side is free | Two stacked drawers, a roll out tray, or a tip out plus a half width tray | Two orders with their own numbers, or the under sink pull out page |
| PIPE THROUGH THE CABINET FLOOR | Box front line to the pipe; pipe to each side | Notch reaching forward to it when it is 3 in from the front and sides; otherwise a shallower plain box or the instant quote | “Distance from the front to the notch (inches)”, or “Custom Depth (Inches)” on a custom drawer box |
Have your numbers? Build your U shaped sink drawer: the Top view draws your legs, notch and front section to the 1/32 in, and a red warning holds Add to cart on any box we cannot build as entered. Still unsure which fix is yours? Send us a photo and your measurements through the instant quote.
What to pick in the configurator
Each fix above is one field. Here is where it goes and what to enter.
| Fix | Field | What to enter |
|---|---|---|
| NOTCH SIZED TO THE TRAP OR DISPOSAL | “Notch width (inches)” | The span plus about 1 in each side, 3 to 29 31/32 in |
| NOTCH MOVED TO AN OFF CENTER DRAIN | “Distance to notch center (inches, from the left outside edge)” | The plumbing midpoint minus the slide clearance on the left, 4 1/2 to 31 1/2 in, as a whole inch plus a fraction to the 1/32 in (17 1/16 in is 17 plus 1/16) |
| NOTCH STARTING CLOSER TO THE FRONT | “Distance from the front to the notch (inches)” | Distance to the frontmost pipe minus about 1 in, 3 to 27 in |
| LOWER BOX UNDER VALVES OR A DISPOSAL | “Height (Inches)” and “Height Fraction” | 2 to 12 3/4 in, top about 1 in below the lowest item over a leg |
| LEGS THAT STOP IN FRONT OF THE VALVES | “Depth Selection” for undermount runners, or “Custom Depth (Inches)” for side mount | The slide length, for example 18” Inches (D) |
| UNDERMOUNT RUNNER | “Notching”: Notched & Drilled For Undermount Slides, then “Slide Brand/Model” | Your exact runner, such as Blum TANDEM plus BLUMOTION 563 from our undermount slides, with its front locking devices under “Clips” from clips and brackets |
| SIDE MOUNT SLIDES | “Notching”: None | The box gets the plumbing notch only; Würth PRO100 and other side mount slides need a box 1 in narrower than the opening |
| EVERYTHING ELSE IN THE CABINET | “Plumbing notes (optional)” | Disposal, valves, hoses and the height of the lowest item over each leg |
| TWO NOTCHES, AN L SHAPE OR A PARTIAL HEIGHT NOTCH | Instant quote | A photo with a tape measure in it and your measurements |
The U shaped sink drawer configurator guide walks every field with its price. We check your three numbers against your box size before we cut, and contact you if they do not add up.
Pipes in the way questions
My drawer hits the P trap. What do I do?
Replace the plain box with one that has a rear notch sized to the trap. Measure the trap’s left and right edges from the left cabinet side and the distance from the box front line to its front, add about 1 in of room (our suggestion), and enter the three numbers in the configurator. A plain rectangular box can never clear a trap that sits inside its footprint.
My sink drain is not centered. Can a drawer still work?
Yes. The notch moves to the drain: enter the midpoint of the plumbing’s left and right edges, minus the slide clearance on the left, as the distance to notch center. The legs come out unequal, which is fine as long as each one is at least 3 in wide.
The drain is close to the front of the cabinet. Is a notched drawer possible?
Usually. The notch must start at least 3 in from the front of the box, and we suggest about 1 in of room in front of the pipe, so a trap whose front edge is 4 in or more behind the box front line works with a short front section. Closer than that, use a lower plain box that passes under the trap, or a roll out tray.
Can I move the plumbing instead?
Sometimes, and it is a plumber’s job. A trap can often shift a few inches side to side with a different trap arm, and supply stops can be moved up the wall, but the drain stub in the wall stays where it is. For most sink bases, sizing the notch to the plumbing is quicker than moving pipes, and the box is cut to the 1/32 inch either way.
What if a pipe comes up through the cabinet floor?
A notch open at the back clears it when the pipe sits at least 3 in behind the box front and at least 3 in from each side; the notch simply starts in front of the pipe and runs to the back. What a rear notch cannot do is leave drawer behind the pipe. If you need that, or the pipe is closer than 3 in to the front, order a shallower plain custom box that stops in front of it, or use the instant quote.
What if there are pipes on both sides of the cabinet?
Two separate pipes need two notches, which the configurator does not cut; that layout goes through the instant quote. If both pipes fall within one span, a single wide notch that includes both works, as long as at least 3 in of leg remains on each side. Supply lines near the back wall are often better cleared by an 18 in slide so the legs stop in front of them.
Can the notch be made bigger after I order?
No. The box is built to your three numbers and is not returnable, so measure before you order. Before we cut, we check the three numbers against the box size and contact you if they do not add up, and the live preview holds Add to cart while a red warning shows. If we built it wrong or it is defective, send photos and we remake it.
Related reading
- What is a pipe chase drawer: every name for the drawer and the geometry in one drawing.
- How to measure plumbing for a U shaped drawer: the three numbers step by step.
- U shaped drawer with a garbage disposal: the disposal body, the cord and double bowl sinks.
- Two U shaped drawers in a sink base: the stacked layout when one box cannot clear everything.
- Sink base storage options: U drawer, tip out, roll out tray or shelf.
- U shaped drawer installation: checking the notch against the real plumbing before mounting.
- Under sink pull out drawers: the low tray route when the doors stay.
Pipes in the way? Build the box around them
Enter your box size and three notch numbers and we build a dovetail U shaped sink drawer that clears your plumbing, built to order in our Las Vegas shop and cut to the 1/32 inch. Build yours in the configurator: the price and the drawing update with every choice, the wood box carries a lifetime warranty, and retail shipping is free.