Flooring Tile - Hairline crack across 7 tiles? Builder says its ok...

Here's my situation:
2 Yr old house, unfinished basement, and in the kitchen on the 1st floor, there is a small crack that runs across about 7 tiles. The house is still under warranty, but the builder is doing the repairs...he's pretty biased-so what's the deal, should I get a structural engineer to look at the subfloor before saying, "okay, builder, go ahead and fix it..." When in the back of my mind, I'm thinking "This is gonna crack again...and that time, it will be out of warranty."

Is my builder denying the fact that the subfloor may be installed incorrectly?? There is one other spot in the kitchen that has a VERY small crack in the grout.

Anyone know of a service that will do this inspection (with a report that would have to possibly hold up in small claims if it comes to that) in Southern IN/Louisville area?

The Tile Council of North America has inspection services available. Check out this link and contact them.

http://www.tcateam.com/

In the mean time, why dont you give us some details so that we can have some fun diagnosing this. Give us the details of the floor. What size are the floor joists, what is their on center spacing and what is the unsupported span of the joists? How thick is the subfloor, and what is it, plywood, osb? Is it tongue and groove or square edge? What is the underlayment, more plywood, cement board, an isolation membrane? What was used to adhere the tile, mastic, thinset (name of a product would be helpful)? Is the tile ceramic or natural stone?

If the structure is not adequate, replacing the tile is likely to crack again.

I'm really not an expert on this matter! So I'll try to answer your questions...but please be aware-I'll be doing so in "layman's terms"! Here goes...
The joists are the "Silent Floor" type engineered "I-beam" type joists. There are no "poles" in our basement-the footprint of the house is a basic rectangle. We have a support wall through the middle of it. I was not here when it was built, so I can't answer the question of what was used to adhere the flooring in the kitchen...which has ceramic tile, by the way. All I can see in terms of floorboard from the basement is plywood. That's about all I know about the flooring construction. Sorry if I'm frustrating you!

I not an engineer but have seen these I-joists before. They are usually, from what Ive seen engineered and installed to a deflection of L480 which is more than enough for ceramic tile. The problem with them is that their on center spacing is more than 16", it's usually 19.2" or 24". Steps need to be taken to increase deflection between the I-joists, usually additional plywood and uncoupling membrames that will stiffen the floor between the joists and isolate any joist and subfloor movement from the tile. What is the on center spacing of the I-joists? You can measure this from the floor down below where you can see the plywood subfloor. Are the 7 tiles cracked over an I-joist or between 2 I-joists? Perhaps you can measure from a common exterior wall upstairs and downstairs to determine this.

The crack runs perpendicular to the joists...so across probably five joists. By the way, I do believe the I-beams are about 16 inches apart. No way ours are 24.

I love playing these guessing games. Actually, I hate it because it shows how many people out there shouldn't be installing tile.

Measure from the wall to the crack from either direction. I'll bet a shiny nickel that it's distance from the wall is very closely divisible by 3', indicating that it's a seam failure along the length of cement board. That would be an early sign of tenting if the cement board was tight to the wall or untaped cement board edges or cement board installed by just dry laying it or using construction adhesive from a caulk gun. Or everything could be properly installed with perhaps an untopped kitchen island on install day that later got a huge slab of granite put down on top and the stress of that weight not there on install of the tile has finally caused enough fatigue on the system to cause the crack.

Some other investigative stuff you could do to help us determine any errors would be to remove a piece of base board and see if the area between the wall and tile is grouted. If it is, cut out the grout since it can't be there for the floor to survive anyway and see if the cement board is tight to the wall. If you can, pull up whatever transition is at the doorway and either reply in detail what you see or better yet would be to post a picture to a photo sharing site and link it here.

Also, unless your builder knows which lot # and caliper they came from and has extra tile from that particular batch, forget about it matching.

We also have yet to find out if these are ceramic or stone and what size are they?

Get some info from the builder as well. Heck your entitled to it. How thick is the plywood subfloor and is it square edge or t&g? How was the subfloor fastened to the joists, nails, screws, construction adhesive? Was the subfloor plywood sheets gapped properly for expansion. Whats over the subfloor (underlayment) more plywood, cement board, an isolation membrane? If cement board, did they bed it in thinset or just dry lay it and screw it down? Did they tape and mud the cement board seams? Did they stagger the seams so that 4 corners dont line up? You should try to get as much info from the building about the make up of the floor as possible.

Brian - I think your onto it with the cbu seams. Im not taking that bet.

Live dangerously Johnny, it's only a nickel :)