Many products suggest that this can be down. I have seen first hand a Porcelain Tile installed over Sheet Vinyl and got to look at the entire install up close and personal while I was ripping it out! The worst thing - it was down at my Nana's home. Some pirate, some cowboy took advantage of my Nana and charged her over $6,000 to install Porcelain Tile in her kitchen (tile cost $5.50 square foot and the total square footage was 300 square feet). I went after the guy who did this installation and he was not interested in dealing with me and took my suggestion of buying my Nana new tiles and giving her back $2,000.00 dollars so I could buy new cement board and reinstall this floor. In the end my Nana got what she wanted at premium price (still don't no why she didn't call me in the first place???) and I learned a lot about this type of installation. From my findings it's the amount of cushion in the vinyl and that a lot of prep needs to be done to rough up the surface. I have not found one person who has done this with success and when asked by new clients I retell this story and simply tell them I won't install this way - period. Good luck with your remodel! "When it's perfect. It's good enough." - John Whipple

I'd recommend adding a layer of 5/8" thick underlayment over your subfloor. Offset the seams of that layer from the seams of your existing subfloor. Screw it down, fastening it to the existing subfloor, but not to the joists. When you put down the 1/4" hardie, use thinset between the hardie and the new underlayment. You can use unmodified thinset (less expensive), you're not looking for bond strength, just a bedding material that will eliminate any vertical movement due to micro-gaps between the hardie and the underlayment. You'll also screw or nail the hardie down, that will be the bond strength so to speak.

The Ardex 8+9 will handle that OK. I used a little mesh and thin-set as a double down approach on a couple cracks in this room myself. Not needed by the book but I thought it could not hurt. Level changes are the worst. These can be settling cracks and the settling can still be going on. Little cracks are common. These are the cracks I covered with some mesh and some thin-set. I let this dry out a few days before adding the Ardex 8+9 Crack Isolation over top. The spray foam was used to fill the gap under the drywall. Block Silver Fish from having a home. I cut it back so it was 1/2" high and a 1/2" wide. This will give me a compression zone later when I tile and prevent the tile from being installed two tight in this Sun Room.

hahahaha... you guys really crack me up. So sorry for the lack of updates for over a week -- after that site meeting last Thur AM, we flew out to Asia for our 2 week vacation (hence the silence). Bottom line from the site meeting was that the engineer confirmed that structurally, NOT correcting the slanted beams will not present any structural issues (same conclusion as the independent engineer I hired). I think there's also a concern that an attempt at such a fix MAY create new issues (it's not a simple fix at this stage since walls and roof are already up). So I decided to tell the GC to leave the beams as they are, BUT re-work the floor joists so that the second level floors are level (well, at least level within the 1/4" per 10' tolerance per code -- when we left we were at 1/2" per 6.5' per my leveler). There was also a list of about 10 (more minor) items the engineers pointed out as requiring fixing. I've been in touch with the GC via text/email the last few days and apparently they have been working on the list. Supposedly they've finished the work to level the second floor, but I don't know what the results look like... can't wait to get back to see for myself in a week's time (fingers crossed!). Still somewhat upset that I'm paying a boat load of money for a house with crooked beams. Oh well... :-(