Flooring Tile - dip in floor, can it be repaired for tile installation?

Just purchased a new home, and I'm in the process of doing some remodeling. One of the rooms I'm doing first is the kitchen. The kitchen has a 6.5 ft by 12 ft "bump-out" addition off the back of the house. The previous owners had carpeting in the kitchen, and we noticed a slight bump in the floor where the original floor ends and the addition begins. The home inspector looked under the crawlspace beneath the addition and noted that everything looks structurally sound, and standard 2x8's were used for floor joists, 16in apart, running along the 12 ft length of the floor. He suspected that the bump was due to the addition settling. The previous owners stated that the addition is at least 25 years old (length they lived in the house, it was there when they moved in), so its most likely very stable.

After taking up the carpeting, I discovered that the bump is actually the start of a dip in the addition floor. The deepest the dip goes is roughly 1/2-3/4in. The subfloor of the addition is just 1/4 inch particle board. The subfloor of the original kitchen is hardwood with OSB nailed on top. The kitchen cabinets and counter top run along the wall that spans both the original floor and addition.

I would like to install ceramic tile, but I will compromise with vinyl if ceramic is impossible My questions are: How feasible would it be to level the floor out. My first idea is to remove the existing subfloor over the addition (either replace entirely or cut around the cabinets). The second idea is to nail in OSB or plywood in the deepest part of the dip, and fill in the other areas with leveling compound. Removal of the cabinets and countertops for an overhaul of the floor is not possible. They are brand new and wouldn't want to risk ruining them. Will either of these methods allow ceramic tile to be installed, or vinyl? I have little carpentry experience, would professional carpenters even consider doing a job like this?

Thanks in advance!

Surely there was more than 1/4" particle board subflooring. Not seeing it puts us behind, so I would suggest (if there is sufficient subflooring) that you use self leveling compound in the dip and install your cbu over that for your tile install, setting the cbu in thinset and screwing it properly according to manufacturer's suggestions.

Thanks for the reply. I truly don't know how thick the particle board subfloor is. The only part I can see is where a radiator pipe goes through a hole cut into the floor, so I can't make an accurate judgement. It does give slightly between joists when walked/jumped on, so I didn't think it was was very thick.

Particle board has no place in a tile installation. It has to go if you want ceramic. Replace with at least 5/8" plywood or OSB.

Bandit

You have several issues to deal with if you plan to install ceramic tile.

For starters, 2"x8"s are overspanned for ceramic tile at 12'. You'd have to do something to either shorten the span or sister the joists.

The pariticle board has to go, as its not an acceptable subfloor for ceramic tile.

I think you need to start out by finding out why you have this big dip in the floor and correct that first. It sounds like it could be a structural problem.

A word on self leveling compound and ceramic tile assuming a proper subfloor and adequate joist structure is already in place. The slc would have to be a portland based product. It would have to be poured to the minimum thickness as specified by the manufacturer, usually 1/2" or so at the thinest part of the pour. No cement board would be required. You'd set the tile directly to the slc. Never use cement board over slc, as the screws or nails you drive through the slc will just crack it and make the floor unstable. If you use slc and cement board, the cement board goes down first (bedded in thinset) then the slc could be used over the cement board.

Considering the amount of work involved here to be able to install a ceramic tile floor, you may want to pick a different type of flooring.:)

I'm perfectly OK with installing something other than ceramic. I asked the questions because I wanted to have all my options out there and considered before deciding on flooring. I just don't want to have carpet in the kitchen, which is what was there previously!

After using the self-leveling compound, should I be ok with installing vinyl?

I had originally wanted laminate, but obviously the flatness issues made a floating floor impossible. Is there a type of laminate that is fastened to the floor rather than floated?

Has anyone worked with this product? It's a Dap brand self-leveling compound that is silicone based. It's supposed to flex with the subfloor, which seems like it would work better for my situation than standard self leveling compound (provided the underlying structure is sound, I'm having that inspected).

DAP Products - Repair Products - DAP® Flexible Floor Patch and Leveler (RTU) (http://www.dap.com/product_details.aspx?product_id=341)

Has anyone worked with this product?

That may be ok for vinyl. I'd not use it with ceramic tile, even though the instructions say you can. for ceramic tile you need a cement based patching compound that you mix yourself. Nothing coming from a bucket is accepatable for ceramic tile.:)

Had an inspector come out and look at the foundation and floor last night. He said that because of the way the joists are going (12 ft along the long wall), that ceramic would always crack at the border where the addition begins. He said to either sister in something stronger or do some sort of reinforcement to the ground. I'm not willing to go through all that work and expense, so it looks like it's going to either be vinyl or laminate. Carpenter is coming out today to start work on repairing, leveling the floor (friend of the family).

Thanks for everyone's help and advice!

Bandit

I think the vinyl or laminate is a good choice and will work better in your situation. Ceramic tile would be risky here.:)

Bandit,

RE: Had an inspector come out and look at the foundation and floor last night.

Was this a town inspector, or someone you hired?