The old cabinets came out and the wall behind them has opinions: a drain sticking out four inches, an outlet exactly where a drawer box goes, a heat register in the floor under the run. Some of these you cut around, some you go around, and some are somebody else’s job.
Every kitchen wall has a second layer: the pipes, wires and ducts that fed the old cabinets, put in by whoever was there before and sized to whatever stood there then. Your new plan was drawn on a clean wall. The two meet on install day, usually with a cabinet in your hands. The good news is that almost every collision falls into one of three answers — cut around it, go around it, or have it moved — and which one is rarely a judgement call. It depends on what the thing is, which box it lands in, and whose licence it falls under.
It depends what is in the way. Supply and drain pipes into a sink base come through the back panel: cut holes between the mounting rails, about ½″ bigger than the pipe, from measurements or a template. A pipe behind any other box: put a door cabinet there rather than a drawer cabinet, notch only the back panel and shelf, or run the pipe low through the open leg space under the box. An outlet that would end up buried behind a cabinet is moved by an electrician. A floor register is ducted to a toe-kick grille, and a radiator or baseboard heater is relocated by its trade — never boxed in.
The day the old cabinets come out is the one day you can see everything. Spend twenty minutes on it and install day becomes carpentry instead of improvisation.
| What is in the way | The usual answer | Whose job |
|---|---|---|
| Sink supply and drain stubs | Cut around: holes in the sink-base back | You |
| A pipe behind any other cabinet | Go around: door cabinet, notch, leg space or furring | You — or a plumber to reroute |
| An outlet behind a cabinet | Move it, or keep it reachable inside the cabinet | Electrician |
| A floor register under the run | Duct it to a toe-kick grille, or move it | You, or a heating contractor |
| A radiator or baseboard heater | Move it; never box it in | Heating trade or electrician |
| A gas line or shut-off | Keep it accessible; design around it | Licensed gas fitter |
| A stack, chase or structural post | Change the cabinet, not the obstacle | You, on the plan |
On a full renovation with the drywall off, moving a stub a few inches or dropping an outlet below the counter line is a short job. Once the wall is closed and tiled it is a day and a second trade. Measure against the plan before the drywall goes up, not after.
The sink base is meant to have pipes in it, so this is the one collision that is not really a problem — as long as the holes land in the right place first time. The sink guide covers where the stubs should be and what else lives in that cabinet; here is how to get them through the back cleanly.
The dishwasher is usually fed from the sink base too, with its own shut-off valve reachable without dismantling anything. If the machine itself is the one that won’t go in, that is a different page.
A drain or vent line that runs along the wall, a water line to the fridge, an old radiator pipe that nobody removed: these land behind ordinary cabinets, which have no reason to expect them. Work through the options in this order, cheapest and least destructive first.
Wall cabinets meet pipes less often, but vent stacks and ducts do run up behind them. An upper hangs on its rails, so the same back-panel notch between the rails works, with the shelf notched to match — and the screws must still reach a stud, which a pipe sometimes sits right in front of. If the only stud is behind the pipe, see there’s no stud where the cabinet goes. The cabinet over a range hood is the one upper that is meant to have a hole through it, for the duct; the appliances chapter covers that.
The rule is short and it is not ours to bend: an electrical box may not be enclosed and made inaccessible. A live outlet buried behind a cabinet back is a fault nobody can reach, inspect or reset. So the question is never whether you can cover it — you cannot — but which of three situations you are in.
Wiring between outlets often runs horizontally through the studs at about outlet height. A cabinet screw driven an inch into the stud at that height can find it. Where you know a cable runs, fasten through the other rail, and turn on the live-wire mode of your stud finder if it has one. This is the one place on install day where a screw can do more damage than a split stud.
The temptation is to set the cabinet over it and forget it. Don’t: a register blowing into the closed space under a run of cabinets gives you a cupboard full of dust, a warm base that dries out whatever is stored above it, and condensation where warm air meets a cold floor. There are two good answers.
A return-air grille — where air goes back to the furnace rather than coming out — is a different matter. It needs open area to breathe, and under a cabinet it would pull dust from the leg space into the system. Relocate a return; do not duct it into a kick.
Heaters cannot go behind or under cabinets. Boxed in, a radiator heats the inside of the cabinet rather than the room, and the cabinet is combustible material pressed up against a heat source whose maker specifies clearances to exactly that. Three ways through it:
Plan this at the measuring stage, not the install. A radiator is the size of a cabinet; finding it in the way on install day means a cabinet with nowhere to go.
None of these is a cabinet failure. They are the room telling you where the cabinets cannot go, and the plan is the cheapest place to listen.
Put the survey photos next to the plan and go box by box. If you can tick all six, install day has no surprises behind the cabinets.
Whoever installs — you or someone you hire — should have the photos and the marked-up plan on the day. When the boxes do go up, the screws still need studs behind them; and the install chapter covers the levelling that every hole above depends on.
Yes, in the back panel of a sink base or a door cabinet, between the mounting rails. Measure each pipe’s centre from where the cabinet will stand, drill a small pilot from the outside, then cut the hole with a hole saw from the inside out. Never cut through a mounting rail or a side panel: that is where the cabinet’s strength is.
About half an inch larger than the pipe, so the cabinet can slide over the stubs and still be adjusted. If a shut-off valve or fitting is already on the pipe, the hole has to clear the fitting instead; cover a larger hole with an escutcheon or a collar, and seal the raw edge of every hole.
Not if the pipe stands out from the wall into the cabinet. A drawer box runs nearly the full depth and has nothing to notch, so the drawer will hit the pipe. Put a door cabinet there instead, whose shelf can be notched, or route the pipe low through the open leg space under the box.
If it is in the sink base, it simply comes through the back panel. Anywhere else, put a door cabinet there and notch the back, fur out the wall so the whole run stands clear of it, or have a plumber shorten or reroute it before the cabinets go in. Rerouting is easiest while the wall is open.
No. An electrical box may not be buried behind a cabinet where nobody can reach it. Have an electrician move it, often to above the countertop, or keep it deliberately inside a cabinet with an opening cut in the back panel so the outlet and its cover plate stay reachable. Which of those is allowed is the electrician’s call.
Not blowing into the space under the cabinets, where it makes dust, condensation and a warm cupboard. Duct it under the box to a grille in the toe kick, or have the register moved before the cabinets arrive. A return-air grille should be relocated rather than covered or ducted into the kick.
No. A heater boxed in behind a cabinet heats the cabinet, not the room, and the cabinet is combustible material close to a heat source. Leave that stretch open, have the heater relocated by the right trade, or replace its output with a heater designed to sit in the toe-kick space under a base cabinet.
Notch when one cabinet is affected and the notch stays in a back panel or a shelf. Fur out when a pipe or a ledge runs along most of the wall, so every box stands forward by the same amount. Furring moves the whole run into the room, so the countertop gets deeper and the ends need fillers or end panels.
Fit a collar or escutcheon over each pipe, or run a bead of silicone between the pipe and the hole once the cabinet is fixed, and seal the cut edge of the hole as well, because raw board swells when water reaches it. Sealing also stops drafts, smells and mice coming into the cabinet from the wall.
Twenty minutes with a tape and a camera the day the old cabinets come out, and every pipe, wire and duct has a planned answer — cut, routed, or moved by the right trade before install day.
Draw the walls in the free designer →