How to reduce 1-1/2" sink drain to 1-1/4" ptrap

Ive got an Ikea sink and vanity combo that comes with a 1-1/2" drain line and p trap. Unfortunately, I realized today that I have a 1-1/4" galvanized drain line coming from the wall. Because there is very little space behind the drawers in the vanity, I can't put a fitting on the galvanized pipe to increase the size to 1-1/2. It seems that my only real option is to find a way to reduce the 1-1/2 down pipe/tail pipe, to the 1-1/4 p trap. Is there a product for reducing the size of the down pipe? If not, is there any reason I couldn't just use a rubber coupling with stainless steel clamps to connect the two?

1 1/2 to 1 1/4 reducing washer with nut for the reduction. It looks like the normal 1 1/2 nut but it’s inside is slightly thicker. Very common

Thank you for the info! Can you send a link to the product? Preferably from Home Depot or Lowe’s? Two separate “very experienced” plumbers at Home Depot had no idea this reducer nut exists so I want to make sure I can find it when I get to the store.

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Turns out that the reducer washer and nut works if you have a 1-1/4" pipe coming down from the sink that you need to adapt to a larger 1-1/2" drain but as far as I can tell, there is no way to do the other way around when you've got a 1-1/2" coming from the sink to a 1-1/4" wall drain. Makes sense because the threaded nut comes from the top so theres no way to fit a nut that threads a 1-1/4 pipe onto a 1-1/2" pipe. Just wouldnt fit. So I ended up just using a rubber coupling. Seems to work fine.

frodo said:

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cant build out from the wall because the vanity drawers don’t leave enough space so this wouldn’t work. This is what I just did. Seems to work fine.

Somewhere I heard it wasn't kosher to go from larger to smaller in a waste line, but a PVC Reducing Coupling, Socket x Socket, 1-1/2" x 1-1/4" Pipe Size - Pipe Fitting (Lasco #429212) could be turned around to do just what you're doing with the rubber coupling. But I'd prefer the rubber coupling for ease of future maintenance. It'll be all hidden by stuff you store under the sink anyway, so anything will work,

Mikey said:

Somewhere I heard it wasn't kosher to go from larger to smaller in a waste line, but a PVC Reducing Coupling, Socket x Socket, 1-1/2" x 1-1/4" Pipe Size - Pipe Fitting (Lasco #429212) could be turned around to do just what you're doing with the rubber coupling. But I'd prefer the rubber coupling for ease of future maintenance. It'll be all hidden by stuff you store under the sink anyway, so anything will work,

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You read it in the plumbing code.
Can be done with a "poetic license".

I think you just built a point of failure. The rubber coupling should be a couple of diameters higher, so it is well above the top of the line going into the wall, and never sees standing water.

Michos said:

cant build out from the wall because the vanity drawers don’t leave enough space so this wouldn’t work. This is what I just did. Seems to work fine.

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I have the same issue with my Ikea sink and drain. I thought I bought the same flexible connector as Michos, but mine is bigger on one end. The one in your picture appears to be the same size on both ends, which would provide a tighter fit. My question is did you slip the flexible connector over the threads at the end of the P trap, or did you cut the trap to remove the threads? Also, any issues with the flexible connector after using it for a while?

Thanks.

So IKEA makes this drain connector that will take you down to 1 1/4 that came with my faucet. Then you can buy this 1 1/4" kit that will work with it.