Was doing some cleaning after the kiddo went to bed, and as I was letting water or of the sink after doing hand wash, I thought I heard dripping. I opened the cabinet to see if the disposal want secured right, and the ****ing thing was leaking through the bottom. It's obviously toast.

However, it looks like this might have been going on for awhile. There's some light water damage to the base and the very bottom of the cabinet sides on the inside. I want to replace the bottom because there's some swelling and peeling. The inside corners also have gaps, so I'm wondering just how much water has gotten under the cabinet itself and what that damage is. Hopefully not much because we typically don't fill the sink and just run hand wash through it, but there's no telling how much of that water has actually been going down the drain.

Any advice on replacing the bottom? The sink cabinet is between another prefabbed cabinet and the dishwasher, with a stile between the two cabinet doors. Pretty sure I'll have to do it in multiple pieces. I guess I could try to remove the dishwasher and side, but that seems like a lot more trouble than it's worth.

no way in shape is this actual advice from a professional, but I don't see how you could actually replace that bottom. I am guessing it is builder grade cabinets. I would sanitize the hell out of it with bleach and sand any visible spots. Then place sealed/painted 1/4" plywood down across the bottom for structural support. Probably will need to be two pieces with the middle door block but if you glue them down, they shouldn't move.

I am sure someone with more experience will come along and give you a better option, but that is my best shot at it

Yep. It's basically particle board with a paper like veneer. Sanding won't do much with that. I figured I'd need to put in a new bottom in two pieces. Maybe put 1/4" veneers on the sides and back.

Also, go to home depot and buy an under sink mat. They are just thick plastic, but they will prevent damage from a small leak.

What builder93 said and then buy one of these:

Xtreme Mats Under Sink Kitchen Cabinet Mat, Pick Your Size, 33 5/8 x 21 7/8, Grey https://www.amazon.com/dp/B00HFXMH6K/ref=cm_sw_r_cp_apip_Lw1WLVbPNieC9

I love these things. I've put them under all my sinks.

Builder93 said:

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You need to remove the board because it probably has mold growing on it and you need to clean underneath it. Cut the board down the middle and then pry it out. It will come out of the groove in the edges. Clean underneath with something to kill the mold Vinegar and water is your best bet. Bleach is not as good because it only stays on the surface of the wood. Build a frame around the edge with 1x4's and then a 2x4 down the middle. Cut two pieces of plywood that can drop in from the right and left and meet in the middle. Caulk the joint well and all around the edges and paint it with multiple coats of paint. I have done this quite a few times.

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Concrobium for the mold/mildew

https://www.lowes.com/pd/Concrobium-32-oz-Liquid-Mold-Remover/50053503

Then on the bottom plywood panel I always use an oil base primer which will help prevent separation in the future when something leaks again

Had a mat. Pulled everything out to get up all the water. I'm kind of thinking about coating the bottom and 2" up the sides in a few layers of flex seal.

This is more what I need. I like the pan sides.

JP76 said:

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Builder93 said:

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You need to remove the board because it probably has mold growing on it and you need to clean underneath it. Cut the board down the middle and then pry it out. It will come out of the groove in the edges. Clean underneath with something to kill the mold Vinegar and water is your best bet. Bleach is not as good because it only stays on the surface of the wood. Build a frame around the edge with 1x4's and then a 2x4 down the middle. Cut two pieces of plywood that can drop in from the right and left and meet in the middle. Caulk the joint well and all around the edges and paint it with multiple coats of paint. I have done this quite a few times.

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Concrobium for the mold/mildew

https://www.lowes.com/pd/Concrobium-32-oz-Liquid-Mold-Remover/50053503

Then on the bottom plywood panel I always use an oil base primer which will help prevent separation in the future when something leaks again

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If you want something less toxic, Citrisafe. It's magic.

What do to think about flex sealing the bottom and up the sides? Bad idea?

ABATTBQ11 said:

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What do to think about flex sealing the bottom and up the sides? Bad idea?

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I think if you do what builder93 said and buy the mat like in the link you should be good to go. Doing more is up to you.