Kitchen floor soft spot

[Bayflite73]

Hey guys,

I know we usually talk about soft spots in our boat floors and that leads to stringers, glassing questions and the like, but after our breakfast meet yesterday I started pulling baseboards in my kitchen as we're putting in new vinyl tiles to cover our very worn out floor and I found about a 6 inch spot of soft floor by my dishwasher  . It goes about 1/4 inch down, not through the subfloor, but there and demanding some attention.

Anyone have any experience with something like this? Do I need to remove my cabinets, cut out the floor and put in a new subfloor section or would scraping out all the wet crap and using some sort of floor patching stuff work?

Any ideas?

[terry]

if you can chip out the damage to see how thick your sub floor 1/4 ,1/2 etc then you can take a circular saw to the depth of your sub floor and cut out the damage and lay in a new piece.i wouuld go from joist to joist that way you have something to screw to.may have to remove cabinets if saw will not fit.

[WetRaider]

Josh -

If you're putting new flooring down, you can just about patch it however you'd like.  Replacing a full section of the subfloor is obviously the best long-term solution.  
Besides the floor, the first thing I would suggest you check is all the plumbing in and around your dishwasher.  You don't want to replace the floor and find out a previously undetected leak is causing the problem to continue.  If you were pulling baseboards and noticed the floor, that suggests your dishwasher is up against the wall on one end of your cabinetry - replacing the floor top down isn't going to be easy, because the sill plate and wall rests on top of the plywood you'd need to pull out.

If your basement below the kitchen is unfinished, you might be able to cut out the subfloor and replace from the basement side without having to remove the cabinets.  Have you pulled the dishwasher out to see what shape the floor is in under that section of cabinet?  It is common for the seals on a dishwasher door to wear out and the steam will build up and condense on the insides of the cabinet walls, drip down and wet the floor.  I use to make my granite installers seal the underside of a countertop over a dishwasher, too, for the same reason - the steam would wet the granite all the way through and it would appear discolored/stained until the moisture went away.

My neighbor mixed up bondo and fiberglass resin to patch the subfloor in his house.  It stunk up the place, but a belt sander got it smooth and his new floor laid right down on top without any problem.  

[Bayflite73]

Turns out a hose is cracked in the dishwasher. It's 13 years old so I'm not surprised. My basement is unfinished so I know the water damage doesnt go all the way through. After a trip to Home Depot I'm going to start by using a utility knife to cut out the bad vinyl and then dig out the bad rot to see how deep and extensive the problem is. If I have enough floor that's good maybe a floor patch is the good enough answer.

[Jason]

I would just do like Terry was saying and just replace what is bad. your sub floor SHOULD be two layers of 5/8" plywood. I bet you only need to replace a small part of the upper sheet.

I would avoid removing the cabinets. You would need to remove the countertop too which is probably glued down and if you have any seems you'll never get them to look nice again.

[WetRaider]

If your basement is unfinished, you should have an easy time with it.  I would suggest, though, rather than cutting from the center of one joist to the center of another, that you cut inside to inside - then, from the basement side, screw in a 2x piece of material on the inside of each joist at your hole to give you a full inch and a half support at the ends of your new subfloor patch  ...  when you've only got 3/4 inch overlap, minus 1/8 tolerance, that's only 5/8 and with some concentrated weight that short span can sag enough to pull free from one side or the other.  It's not very likely, but still possible.  A wood finished floor would add some structural stability, but vinyl's tiles will remain flexible. 

[Hotwired]

All great advice, I would add to be sure to get it very well dried out before completing any wood replacement and eventually covering the area under the dishwasher with a piece of sheet vinyl.  That is one area often overlooked when doing flooring replacement or even original installation and yet it is one of the most likely places where moisture will accumulate.

[Bayflite73]

Good points everyone. Thanks much! It's turning into quite the task. Dishwasher is now in the garage using mainly a hammer and chisel due to space constraints and the number of allergy sufferers in the house (minimize dust). Ugh. I think I'll not pull up my carpet in the boat. Ignorance is bliss!