Laying Out Sink Base Cabinets for Plumbing Stubs

Creative cosmetics, advanced math, and inspired guesswork are all it may take for you to punch perfect plumbing holes every time. November 19, 2008

I have a sink base that needs to be installed. Two water supply and two drain pipes come up through the floor of the cabinet. This particular cabinet has to be positioned precisely in relation to an adjacent cabinet. Besides measuring 5-10 times and hopefully only cutting once, are there any other tricks of the trade that I am not thinking of? I had thought of cutting a single hole for the 4 pipes and using some type of rubber sheet/gasket with the 4 holes and pulling that down over the pipes (would form a collar around the individual pipes) and glue it to the deck of the base.

Forum Responses
(Cabinet and Millwork Installation Forum)
From contributor F:
There are no tricks to the trade other than to measure it and drill the holes. If you are worried about making a mistake, use a piece of 1/4 plywood as a template and measure and drill that to fit then transfer it to your cabinet, so if you make a mistake, just use another piece of plywood and start over.

From contributor C:
Measure, measure again! Just take your time and check your measurement. I drill holes larger than usual (so that it is a little easier to set the cabinet), not too large, but enough so that you can use a flange around the pipes.

From contributor D:
1. Establish a plumb reference line at the edge of the sink base. In your case where the pipes are coming up through the bottom, establish a square line at the bottom edge.

2. Establish a level line at the top edge of the cabinet. In your case off the back wall assuming it's plumb.

3. From the back side of the cabinet lay out your holes using the distance off your reference lines.

4. Drill a 1/8" pilot hole from the back in the center of the holes.

5. Use these holes as a reference to drill the proper size holes from the front. Perfect job every time.

From contributor S:
If you are totally paranoid, flip your cabinet upside down and glue four strips of wood into a template frame. Lay that on the floor and mark on the edge of the template where the pipes are using ticks on the side and back. Set that on the bottom of the box and transfer it all. Drill through the center of your holes with a small bit, as suggested, from the outside to the inside. Then drill with a hole saw from the inside to the outside. The small drill bit hole guides your hole saw, and drilling from the inside to the outside puts the chippy blow out on the outside where it doesn't show. If disaster strikes, you can skin the inside of a cabinet with a 1/4 piece of the same material and redo your holes, though it'd be worse on the bottom of a cabinet because you'd see the edges.

From contributor B:
Seems like a lot of fooling around to me. I'd notch out the entire area of the pipes and put a false back inside the cut area. The plumber can then drill his pipes into the false back and it will appear just like it was coming through the wall.

From contributor M:
I use a tube of cheap lipstick and put it on the ends of the pipes, push the cabinets to them, and cut accordingly.

From contributor J:
What happens if the pipes come out at an angle?

From contributor M:
Then I use linear algebra.