It is right by the shower. The shower is not leaking in any way. I think it is just where the former owners would exit the shower and whatever drips came off of them and were left on the floor make it right to the same spot. So im hoping by raising that area again that the water would pool away from the wall if left on the floor for any reason. Its not that I make a habit of leaving large amounts of water on the floor. I also thought of putting a bath matt at the shower entrance. But just in case the kids run out of the pool and leave water all over the floor (not like that would ever happen LOL) I would like to try and prevent it now while the tiles are being redone. One more thing it is a concrete subfloor. Thanks, Robert Robert

First of all, you still haven't specified whether your floor is "not flat" or "not level." Whatever else you have (or have not) done to get where you are, it would help a lot if you could say whether your problem is level or flat. Also, just to be sure here, if I am understanding you correctly, you installed the 2x4s ACROSS the 2x6s that make up the underside of the house? (Notice the very very NON-technical terms...so be aware that I'm not a builder or knowledgeable in this stuff like some of these people that post here...just sympathetic to rising note of panic in your posts....) The only reason I'm trying to clarify that is because I am wondering whether you installed the 2x4s "upright" (so the "4" dimension is vertical) or "laying down". I'm not trying to pile on to what you have *already* done, but I don't know what the proper distance for SPANNING that 2x4s have, and I don't know whether they can span two full feet if they are flat. This makes a difference because you want to install tile. If your subfloor is bouncy or bends ("deflects" I think is it), then all the tile you install will just crack and plague you and your heirs until the end of time...until you rip the whole floor and subfloor out again and re-do it. Or put in linoleum. Whichever comes first. You say in the top post that the cracks are like 1/4", but in your last post you write that they are up to 1". That's a big difference? Which is it? Does it vary from 1/4"-1"? Have you actually measure or are just eyeballing or going from memory? IF YOUR CRACKS ARE VERY SMALL: IF it were me (and it isn't), I'd probably just put down a very tight layer of Wedi board (thinset and screws/washers), seal the seams so it can hold the next layer, then put down a thin layer of self-leveling compound (though you still haven't said whether your floor is wavy or slanted), and then tile. IF YOUR CRACKS ARE 3/4'-1": Maybe use a layer of plywood (which would be cheaper but harder to cut), maybe tape and thinset the seams (ask someone on this board about this because I'm just brainstorming here), then use the SLC, then the tile. Only plywood will actually help form a floor (which I think you need to do with 1" gaps), not backerboard of any kind. Instead of Wedi, you could use probably any backer board (ask someone here what to do for the seams). But I only know about Wedi because that is what we went with, and I like it because it is light weight (good if you are a female working alone). I don't think your solution is in one step. It feels like you are going to have to create a tight subfloor, THEN level or flatten. I think you have a non-standard thing going on there, and that might not be addressed so easily with just one step before tile. One more thing, just out of curiousity, WHY do you think your floor must be level? Oh yeah, and I would start making your peace with a threshold. Given how non-standard your set-up is, AND the fact that this is DIY (or at least the subfloor), I'm not sure it is realistic to think you can get away with no threshold.

weedyacres, great idea, thank you. i plan to go under the house today (crawl space) to look from below. Shouldn't such a support beam go through floor and to a concrete footing? While maybe this one does, it doesn't look like it from above, that the post / beam sits on top of the plywood subfloor. Maybe it is / was ok to have it done this way so long as there is comparable support below in the crawl space. Interestingly, if that is the case (post sitting on the subbloor, supported from below), I see no toe nails to position it into place, so maybe it does go through. Just doesn't look like it. Odd... Thanks again.

I guess it's still not clear. The 2 story would NOT be adding onto existing foundation. It would be a two story addition on a whole new foundation and I'm trying to figure out if it's cheaper to do one large room addition (new large foundation) or a totally new two story addition tied it into our current house (new smaller foundation). I'm located in the northeast just outside Boston. I would try to plan on just a slab foundation, we already have a basement, and there's no reason to enlarge it. The plan would be for a single floor addition: expand the half bath on the first floor to a full bath and add on a family room and small bedroom. For a 2 story addition, have the family room on the bottom floor and the bedroom above it. We could still either expand the 1/2 bath on the first floor to a full bath or add on a small full bath upstairs too. (we already have a full bath upstairs, but we'll really need an additonal shower in the future as the kids get older). It seems like there's conflicting info here....with a 2 story it would be less foundation and less roofing, but I know a two story addition probably requires a stronger foundation and the strength of the ceiling to hold up the second floor.