Need Advice Hardie Backer

[12ozcurls]

Hello and thanks in advance. Great forum. I’ve scoured the articles but can’t find what I’m looking for. We’re tiling our small guest bath (45 sq ft). Unfortunately there are a couple angled walls and nothing is square (even the walls that are supposed to be. We have 3 sheets of Hardie that fill the space, so only three seams. I’ve fought the Hardie for a day and got all the irregular cuts done but have ended up with a few spots amongst the three seems that are more than 1/8”. In a couple spots it drifts to 3/16” and even to 1/4” in a couple small runs. Am I doomed? I’d assume I can just drive more thin set (using mapei large tile mortar) into the seam before I tape over it with the mesh tape. Thanks for any advice.

Rich

[cx]

Welcome, Rich.

A photo or two of what you're working with would certainly help. Use the paper-clip icon above the Reply dialog box to attach photos from storage on your computer.

I don't recall James Hardie specifying a gap size between panels, but 1/4" would seem a bit large to my thinking. If the gap you have prevents your fastening per the Hardie instructions, that would be a concern. Otherwise, you're on your own deciding whether your gaps are excessive.

My opinion; worth price charged.

[madmantrapper]

Maybe I missed something. Are you talking walls or floor?

[12ozcurls]

Hi All,

Thanks I’m advance. I haven’t done tile in 10+ years and i’m doing a renovation, part of which is a guest bath. Small room 5x8’. Hardie ran width wise. The first of three panels (attached with thin set and backer screws) is slightly out of level. It slopes slightly upwards at the seam with the second board. I ground the edge to make the boards flush but the unleveled slope causes the dry-fit tile (12x24) to rock across the two boards. When held firm against first board it leaves approximately 1/16” gap under the far edge of the tile. The remaining two boards are level and mate up nicely. If I use a 1/2”x1/2”x1/2” notch trowel and back butter the tiles would this be adequate to compensate for the deviation where the five tiles make the transition from the sloped Hardie board to the level one?

Thank you.

[cx]

Rich, it'll help if you'll keep all your project questions on one thread so folks can see what you're working on and what's been previously asked and answered. A moderator can give it a more generic title any time you'd like to suggest one.

I thought you were talking about walls in your initial post and we can see that Paul's question was well taken.

I'm now guessing that when you say level, you're actually talking about the panels being out of plane? Your tiles care not a whit about level, but those large format tiles do want a very flat substrate.

You can try to flatten your tile surface over an un-flat backing material, but I don't recommend it. Always better to properly prepare your surface before you start installing your tiles. But it's entirely up to you how you want to approach the issue.

My opinion; worth price charged.

[12ozcurls]

CK; I have no idea how this second post was attached to my first and unrelated post. I created a “new post” for this one so weird it was some how attached. In the previous post I though I had deleted it altogether before any replies as I figured it out. Trying to level out the Hardie now. There was less than a 32nd deviation in the subfloor but somehow it was magnified after thin set and Hardie added. I was inquiring to see if, given what I have been dealt, a 16th would be a tolerable deviation that would easily be resolved with the 1/2”x1/2” notch and back buttering.

Thanks

[12ozcurls]

Update: first of three hardi backer boards is uniformly unlevel on the long side at the wall. The board is low by 1/4 at the back edge. I’m not sure how I missed this on the subfloor. I laid a 4’ level and just flat missed the edge against the wall. What would be the best product to put on top the one panel of hardi backer to level out the, approximate, 24”x60” section that is 1/4-3/8” low? 12x24” porcelain is going on top.

I attached a graphical representation of the three Hardie panels.
Thanks.

[ss3964spd]

Rich, how large is the area that needs to be leveled? At 1/4 to 3/8 inches the best option might be a self leveling compound, something that can be worked to a feathered edge. Big box stores will have several to choose from.

[12ozcurls]

Hey SS3964spd. Yes, I landed on that as my solution. I purchased mapei self leveler plus. I just finished making my dam with spray foam. Im hoping I can feather the edge with a spray bottle and water as I’ve seen online. The bag says 2-3 hour before tiling with ceramic but doesn’t mention porcelain. Any suggestions? Thanks.

[Tiger Mountain Tile Inc]

Are you wanting to self-level the whole floor or just the low spot? If you're doing just the low spot then you can feather it out with just a flat trowel. Don't spray water.

[cx]

Porcelain is ceramic, Rich.

[jadnashua]

Read the fine print on the SLC. Most require a special primer, and may have a time window after application before you must install the SLC, and many of them also require metal lath when used over a wooden subfloor and a minimum depth over the highest point. The minority can be feathered out and don't need lath, and if you're trying to keep the height down, that's what you need.

None of them literally self-level, especially when poured in a thin layer...think pancake batter...it does not spread to fill the pan, nor will SLC unless you help it along...the surface tension, like a bead of water on a freshly waxed car doesn't spread out without help.

[12ozcurls]

Thanks for info. I primed and poured slc within time window. I moved it around w/ squeegee and smooth trowel. Floor is much better now. About a 16th over about 6’. Room is only 5x10 (apx). I think it’s gonna work out.

[madmantrapper]

Sounds good, 1/16 in 6 feet is nothing