Base kitchen cabinet repair

Hello all,

After a water leak went undetected for quite a while, the base of my kitchen sink cabinet showed a significant concavity. I set out to replace it by following the instructions contained in How to Replace a Sink Base Cabinet Floor | The Family Handyman. I left 2 1/2" of the old particleboard base on each of the 4 sides and cut off the center part. Clearly the part closer to the end wall was humid and rotten and did not offer much resistance to the saw. Coincidentially, at exactly my chosen cutting distance from the end wall, I discovered a wood panel under the base, which was supporting it. From the look of it, it seems that it received quite some water too. I applied a spray product to kill the mold in all the reachable areas. After 24 hours that back panel still looks darker and humid in the center but it's not soft to the touch. My initial plan was to just glue a plywood board on top of the frame provided by the leftover old particleboard base. Now I am not sure whether I should also cut off that back support board and put a new support before gluing the new base. Shall I just wait a few days to see if it dries up completely, or is the wood already compromise and I'd better substitute it? Probably there is mold on the other side, that I could not reach with the spray, but I could easily do it by opening just a couple of holes in it. Also the back wall looks a bit damaged.
I welcome any advice since I am quite inexperienced on this matter. I am attaching a few pics that show the situation.
Thank you

 

Welcome to the forums!

I'd be inclined to remove all the particle board [add lumber if needed to attach the new floor] and then install the plywood bottom. Not sure it would be a good idea to cover up the bottom portion of that receptacle. As long as the wood at the back is dry/solid I wouldn't be overly concerned about it.

 

Once particle board gets wet there is no hope of drying it out and it's all better.

 

Hi marksr and joecaption, thanks for your replies. I'm gonna eliminate that particle board on the back. I'm now entertaining the idea of not putting a new plywood board where the old base was, but just to keep the extra space that was available below. Strange that there was another board there, isn't it? I was thinking of finding the bare floor. The only reservation I have is that covering with the plywood might give an extra layer of protection against a new leak: if the bottom plank rots, it would damage the structure below. What's your opinion?
Thanks again

 

I'm not sure what the deal is with the piece on the floor, could it be the underlayment for the floor covering? [put down prior to the cabinet install] IMO not installing a new bottom and leaving it open would be a little unhandy and make it harder to keep that area clean.

 

I would install new cleats at back and sides, a middle support, and install an entire new deck at the same height it was.

The remainder of the old deck can be removed using channel lock pliers. Grab hold of the edges and tear it away from the side walls in pieces.

 

Hi Handyone, why wouldn't you use the remainder of the old deck as cleats, which seems simpler?Is it to gain that 3/4" in height or are there concerns that contact with the old water damaged particleboard can damage the new plywood deck? I was thinking of using something like bin primer to seal the old leftovers. Thanks for all your answers, I'm learning a lot

 

Particle board once it has gotten wet has no structural strength so it's better to get rid of it plus I wouldn't want to bury the bottom portion of that electrical outlet.