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How to repair water-damaged undersink cabinet shelves in kitchen?

Hello all,

The under-sink cabinet shelves in my kitchen are completely water damaged (see photos).

- Should I remove the damaged cabinet base to inspect whether there is damage to the floor underneath? The foundation is a concrete slab and kitchen has tiles. I don't know what's underneath the cabinet.

- What do I need to do to repair this in a cost effective way? Can I simply install a new cabinet base over the damaged one?

- I was hoping to reconfigure the cabinets to install a dishwasher on the left of the sink. Any advice on if that modification is possible with existing cabinetry?

This is a recently purchased property so I don't have the full history. The plumbing was fixed and there are no current leaks.

kitchen cabinets undersink 1.jpg kitchen cabinets undersink 2.jpg

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MitchellMc

Hi @Tad222222,

The simplest and most cost-effective approach here would be to trim off any protruding nails or screws left behind from the damaged base so they're flush with the inside of the cabinet. You can use a pair of pincers or a small metal-cutting blade for this.

Once the area is cleared, cut some 42x19mm pine to size and install these along both side panels and the back wall at the level you want your new base to sit—ideally, the same level as the original shelf. These timber strips will act as support rails for the new shelf. Fix them into place with screws, making sure the screws aren’t so long that they go through the outer side of the cabinet panels.

You can then have a piece of melamine board cut to the internal size of the cabinet and drop it in to sit on top of the support rails. This gives you a clean, functional base without needing to replace the whole cabinet.

There’s no need to waterproof the concrete slab underneath unless you notice signs of rising moisture or ongoing dampness. As for adding a middle support beam, if the shelf will be holding significant weight, a beam across the middle can help prevent sagging, but otherwise it’s not essential.

Please let me know if you have any questions.

Mitchell

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JacobZ

Hi @Tad222222,

Welcome to the Bunnings Workshop community, it is fantastic to have you with us.

I'd suggest you start by removing the damaged chipboard at the bottom of the cabinet to see how things are beneath. If there is this much damage to the shelving, then there is a good chance that underneath it is in fairly rough shape too.

With the chipboard removed, inspect the vertical pieces that form the walls of the cabinet. If they are still strong and there isn't significant water damage, then you may be fine to just replace the shelf and the bottom sheet, but if their strength is compromised, then you'd likely need to replace the whole cabinet. If you can upload some photos once the shelf and bottom sheet are removed, I'd be happy to give you my thoughts.

If the side walls are solid, I'd need to see how the shelf and bottom sheet are connected to them to advise you on how to repair them. Have a look for screws or angle brackets and let me know what you find.

With the dishwasher, I'd need to see inside the cabinet to see how it is made. Similarly, as long as the side walls of the cabinet are solid and capable of supporting the benchtop above, you may be able to remove shelves and kickboards to install a dishwasher.

Looking at the extent of the water damage, I'd be surprised if there aren't more issues underneath, but I have my fingers crossed for you.

Once you can report back, I will assist further.

Jacob

Tad222222

Thanks for your initial thoughts @JacobZ . I've removed the damaged shelves. There's concrete slab underneath and it looks undamaged. The side walls of the cabinet seem solid to me. The back wall a bit less but overall okay. I'm looking to keep costs down as I think I will redo the entire kitchen in 5 years' time. What's your advice on replacing the bottom shelf? How would I connect it to the cabinet walls? Do I need to place anything between the shelf and the slab (e.g. for waterproofing)? I don't need a middle level shelf but should I put a small wood beam across for support at that level?

And there's no natural space for a dishwasher unfortunately, so I'm scrapping that idea.

Thanks in advance!

MitchellMc

Hi @Tad222222,

Please let me know if you have any questions.

Mitchell

Tad222222

Thanks for all the advice! I got the job done and although it's not perfect I'm happy with it. I cut the shelf in two as I couldn't slide it in with the support beam in place but afterwards realised the beam could be removed temporarily. Hope this holds up until I install a new kitchen.

MitchellMc

Great work @Tad222222 and many thanks for the update. Looks like a solid repair that will hold out until the new kitchen.

Well done!

Mitchell

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