[snic]

The floor of the cabinet underneath my kitchen sink is warped and water damaged. I'd like to replace it with something resistant to water damage. In my experience, small leaks can go for days before being noticed, and by then the plywood is ruined. (A very special middle finger to Moen for their awful faucet - less than 6 months after installation, it developed a leak that we didn't detect until the cabinet floor had a giant puddle.)

I could use new plywood and then install a protective rubber mat, but I want to keep the pull-out basket that's mounted to the floor (it's very handy). So I'd prefer to use a floor material that won't warp or rot when exposed to water. I thought maybe azek, but while that's great for trim, it seems it's not very strong.

Any ideas?

 

[XSleeper]

It's usually wise to cut and fit a piece of FRP into the bottom of any sink base cabinet, and silicone caulk the edges. That will protect the plywood.

3/4" Azek sheet will work if you have the money to spend and want it to be rot free. But IMO that's kind of pointless when the edges of the cabinet are still wood.

 

[snic]

I suppose you mean something like this?

https://www.homedepot.com/p/1-16-in-x-4-ft-x-8-ft-Plastic-Panel-63003/202090190

Will it take screw holes for the pull-out basket without cracking? And would you also screw it down onto the plywood floor (in addition to caulking around the edges)?

 

[XSleeper]

You can use a little spray contact adhesive. It will lay very flat. Predrill pilot holes for your screws.

 

[Old Thomas]

I put a painted piece of luan plywood over mine. I haven’t had leaks, but cleaning products get stored there and after a few years the surface gets nasty. Then I toss it out and cut a new piece.

 

[snic]

Ha, I'd prefer a more permanent solution.

One idea I had while looking up FRP was to use HDPE board, like this one:

https://www.amazon.com/gp/product/B...&pf_rd_p=edaba0ee-c2fe-4124-9f5d-b31d6b1bfbee

The problem is that you can't caulk the edges; I don't think there's any caulk that sticks to HDPE. But I think I would just make some edges that go about 2" up on all 3 sides of the cabinet, using an adhesive that bonds HDPE. So basically it would be a box with a floor and 3 sides. Then just stick it inside the cabinet and screw it down onto the plywood. Waterproof and will last forever.

 

[huesmann]

Depending how pretty you need it to be, what's wrong with a sheet of shower pan liner, or even 10 mil plastic sheeting? You can cut it slightly oversized, turn up the edges, and tape them to the cabinet walls.

 

[snic]

Shower pan liner is an interesting idea, but it would indeed be ugly, and would eventually tear. I'm looking for a permanent solution.

(Ha, maybe I could install some tile on top of the liner, with some nice trim along the cabinet walls... :biggrin2

 

[House Designer]

If you are good with metal, you could form a 1-piece tray out of aluminum sheet that is custom fit to your cabinet. We made metal shoe boxes in junior high shop class with corner tabs and riveted seams. We were graded on whether it held water. No leaks-A.
One corner leak-B. Two corners leak-C. Three corners leak-D. Four corners leak-F.
We quickly learned that you can tap the outside corner lightly with a hammer to close it up before grading.
Nothing wrong with sealing up the corners with silicone caulk if you go this route.

 

[snic]

Dang, I reached 8th grade the year they eliminated metal shop! My brother took it, but I didn't. So either I get him to make the tray, or I watch some youtube videos.

Thanks for the suggestion. I like it (depending how easy it is to bend aluminum sheet). Also nice is that when I screw down the pull-out basket hardware, I can put a dollop of caulk on each screwhead to make that part watertight as well. Which I couldn't do with HDPE.

 

[huesmann]

I only suggested the shower pan liner because it's very forgiving when shaping and placing. You need something that you can effectively glue. Perhaps use House Designer's aluminum tray idea; any potential leaks can be caulked with silicone or RTV.

 

[udraft]

Two piece metal (aluminum is fine) floor. Through bolts for your drawer. Drop right over the old junk or remove the old junk as needed.

 

[snic]

Why two pieces?

 

[udraft]

Why two pieces?

So you can get it in there without dismantling the cabinet.

 

[snic]

Ah, got it. I don't have a center post, so one piece will be fine.

I just realized that a simple sheet will work fine with some silicone caulk around the edges. No need to make a fancy box. So - thanks for all the suggestions! I'm going to go with an aluminum sheet. I might even spray it with some metal etching primer and paint it a nice glossy white.