Rotted Sink Cabinet Floor–How To Fix



hey everybody I'm Ethan James with the honest carpenter comm and in this video I'm gonna show you how to fix the rotted floor of a sink cabinet like this one behind me so this is another thing that I just see all the time I've done this repair maybe 20 times in my life these prefabricated cabinets come out of factories and they put particle board floors in them it just doesn't make any sense because the moment you start to get drips out of the drain lines the supply lines or disposal like this that particle board soaks it up and you wind up with these big dips you can hardly see if there's a really big belly in this floor here and sometimes the stuff will just rot straight through so what I'm gonna do is I'm not gonna take this out the cabinet would essentially fall apart if I did that instead I'm going to make a custom plywood floor that can come in and lay overtop this one like a bridge and there's a couple tricks that I have to use to make that work but I'll show them to you now to begin the repair I just go ahead and pull the internal measurements of the cabinet first front to back and then pull side to side just by the tape up against the left wall and pull to the right and you're looking to get within maybe an eighth of an inch in either of these directions doesn't have to be dead tight I go ahead and write my measurements on the floor of the cabinet so I don't forget them it's gonna get covered up anyways and for our replacement material we're using half inch plywood this is specifically sand apply which is Home Depot's brand of plywood it's cheap it's almost cabinet great it looks good when it's painted so I'd go ahead and set up the saw to cut the the front of back measurement and once I've ripped that down I I set up the side to side cut I don't bother even pulling out a circular saw for this to cut my full panel I set it on the miter saw make my first cut from one direction flip the piece around and then make the finishing cut from the other direction as you can see but this full-size piece won't fit in the cabinet because the face frame at the center obviously won't let it in so we need to split this piece in half I just go ahead and cut it right down the center once again with the miter saw you could of course do this on a table off you wanted to and before I take it inside I marked the front and the back this helps a lot keeping orientation in mind it's easy to get the sides confused and I also put these two little reference marks in the middle to let me know when we're lined up well once that's done I bring them in and I carefully work them into the cabinet don't hit any plumbing too hard don't hit the disposal just kind of tilt them and lean them until they're propped up like this and they'll be resting on the pipes at the back go ahead and mark the locations of those pipes leave your marks about a half inch outside of the pipe location and then also pull measurements from the back of the cabinet to the front of the pipe this is gonna be the depth of the notches that we make to allow our pieces to slide back into the cabinet here I go ahead and bring those measurements out and I transfer them onto the pieces that we're gonna be putting in you can see I just make essentially little squares representing where they're not just go but I'm not gonna cut square notches instead I'm gonna use hole saw bits in my drill to cut circular notches right up at the perimeter of where we want them here you can see a probably a three and a half inch hole saw bit chucked in my drill and I line up that front edge with the front of where I want the notch to be and I just go ahead and bore right down through it there's the three and a half and the other hole saw bitch I just size them by eye basically and I've got a Bosch quick change bit all these pieces just slide onto this mandrel here real quickly it's real good tool to have around so when I have all three of my holes bored I go ahead and set up my jigsaw and I just carefully notch them out you can see I come in straight from the back following my guidelines and then I taper in towards the center to follow the curve of the hole that the hole saw a bit left I just do this by I just go slowly but it ends up making a really nice-looking notch you can see as this piece falls away you just kind of have this this uu shape scoop in the back so I go ahead and repeat that on my other two pipe locations bring them in work them into the cabinet and set them in place and I pull them tight to the front of the cabinet there's any space I've wanted at the back but you can notice I left a little gap around the pipe I don't want our panel touching the pipe because pipes can sweat condensation and it can start another rot process so here all around you tell that I left my notch is just a little shy and I've got the reference marks on the board lined up it weren't quite right the cabinet's a little out of square so I wedged my screwdriver back here and bring the right one for just a little bit and we're not quite ready yet to bring in the other board instead I want to create a way to bond the two boards together better over this dip and we're actually going to use the dip to our advantage I like to create a little plywood ligament to bond the two together out of 8-inch scrap plywood I just cut maybe a three inch wide piece it's like a foot long and then I bring it in and I just use liquid nails to go ahead and put a put a couple dabs underneath the board that's already installed you don't have to do this but it's usually how I start and then I run a bead down this plywood eighth inch plywood piece on the left and I press it up under the board that's already installed and shoot down through it with maybe like three quarter inch Brad's to lock it in place don't shoot through your finger doing this make sure your fingers are out of the way but when that's done you can go ahead and run liquid nails on the exposed side of that eighth inch scrap plywood set the other panel in and just press it down good and hard onto the liquid nails and the scrap plywood and you want to kind of work it back and forth kind of smush that liquid nails into place and now shoot down through the new board with three quarter inch Brad's into our eighth inch scrap piece and this is really gonna lot these two panels together they won't be able to go anywhere the adhesive is going to set up every time and you can get the board's pretty flush doing it this way then I just go around the perimeter and I just put in a few extra Brad's to keep the whole thing from shifting around a little bit you don't have to go overkill you probably don't even have to do that step if you don't want to the last thing we have to do is address this kind of ugly plywood front edge I don't like to leave it like this you could just paint it and caulk it if you want to I like to go a step farther and add a little custom trim piece something about like this this is a little too thick so I go out and this is just scrap pine I go ahead and rip it to a thickness that will conceal that front edge kind of perfectly here you can see I got just one long stick of it and it's just shy of a half inch thick then I go ahead and pull a measurement from the verticals of the face frames on the left side and I cut those pieces like 11 and a quarter put glue on the back of them and then I just shoot them into the front edge of our plywood panels you can adjust them up and down with your finger as you do this smooth out any glue drops but you just need a few Brad's to pin it together and after that the repair is pretty much done here's the wrap-up to the st. cabinet repair see our little screen trends in the front both sides got glue drawing up there the cabinets a little out of square they pretty much fall along I'm not too worried about that you can caulk these seams if you wants you can these nail heads and you can even sand the center seam if you want to my client after I leave is going to paint this with the exterior grade paint that will hold up better than any type of water intrusion but even if he didn't do that this plywood even though it's untreated would hold up way better – any drips or drops from up here then that particle board so this floor should last really good long time it's very strong you see me pushing on it here and so that's how you repair a rotted sink cabinet floor if you enjoy the video please hit like and subscribe below and check us out at the honest carpenter comm thanks for watching we're now offering live video consultations and phone consultations to homeowners nationwide to get your most important home related questions answered by trade expert just visit the honest carpenter

10 Comments

  • Robert Arabian

    April 15, 2019

    I had the same issue in a rental, except the renter let it get so bad, the particleboard was like sawdust. So I cut it out, took 2×4's and framed in underneath. Essentially did what you did, but had a new frame underneath to nail to and then trimmed it out with some moldings inside the cabinet. I skipped the bridge step since I had solid wood underneath that was not bowed. Well done.

    Reply
  • RTPSEV

    April 15, 2019

    Honestly? You just buried some mold in blossom under the new bottom? Even without any drop of bleach underneath?

    Reply
  • Maxima

    April 15, 2019

    I actually cut a hole in the old piece and spray mold killer in there. I've opened up some sink bases and there has been mold. Nice vid

    Reply
  • Ed Over50

    April 15, 2019

    Nice fix, it looked good and if the client chose not to paint it wouldn’t be bad as is . I use puck board often for repairs ( puck board may be a Canadian term – 1/4” white plastic board available at most HD or Lowe’s). Think that might be a good alternative, just shim the dip and glue down, shoot a few brads and the edge would fit behind the face frame lip – save you time and mean more $$ in your pocket.

    Reply
  • Rick S

    April 15, 2019

    Nice job…

    Reply
  • fenikzart

    April 15, 2019

    Did you offer to paint it before you put it in, i think it would have been easier to paint before you put it in.

    Reply
  • Marty Meyer

    April 15, 2019

    well done sir!

    Reply
  • Stephen Dennis

    April 15, 2019

    Thanks for the video! The ligament patch joining both sheets from underneath is brilliant.

    Reply
  • Carlos Chinchilla

    April 15, 2019

    I like your channel, so I subscribed. This is a good repair. Only reason I would demo the old particle board would be to eliminate as much of that mold that was there.

    Reply
  • William Ruisinger

    April 15, 2019

    Nice work! I’ve actually installed sheet vinyl flooring over the new cabinet floor. Usually protects better than any paint would!

    Reply

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