hardibacker 1/4" for ceiling - a mistake?

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Old 02-15-06, 10:32 AM
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hardibacker 1/4" for ceiling - a mistake?

I am in processing of converting my standard sized 36"x36" shower into a shower/steam bath combo unit.

In order to do that I took out three shower walls, ceiling wall, replaced shower pan. Then I put 6 mil plastic sheet on the frame. 1/2" handibacker for three vertical walls.

Did I make mistake for using 1/4" hardibacker on the ceiling (yeah, I gave a slope), rather than the same 1/2" hardibacker as the vertical walls do?

I thought 1/4" backer is light-weighted and easier for me to carry to the ceiling while I was installing it alone. But after installing, I felt there is a little soft in the middle, since there are two studs behind, 20" apart.

Do you think it would be a trouble late on after laying the tiles (I plan to use 2x2 tiles on the ceiling) on that 1/4" backer? Of course, I don't think the ceiling will take any force like the wall does when we use the shower.

Otherwise, I have to tear it off and replace 1/2 backer before laying the tiles.

Your advice is very appreciated.
 
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Old 02-15-06, 11:27 AM
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I'd not only take itout and replace with 1/2", but I'd also install tons of blocking between those ceiling joists to give lots more fastener locations. To top it all off, I'd take everything 1 step further and coat the entire shower with laticrete 9235. Steam showers over backer are supposed to be surface waterproofed and laticrete requires the poly behind the backer, other trowel on membranes say no poly behind, so that rules out the others.
 
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Old 02-15-06, 11:41 AM
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While your at it with the ceiling, if this is a steam shower you should slope the ceiling 2" per foot. I'm not sure this is required by code but it's the way I learned to do it.
 
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Old 02-15-06, 01:07 PM
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Johhny, he's got a sloped ceiling. Covered that in another thread.

If the site would allow us to see another user's other posts, you'd have known that and it would really benefit all of us so we can follow projects better than just from memory and would prevent those who post questions from answeing the same question multiple times. I think that was the 4th time Hobbyjohn has been asked about the slope
 
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Old 02-16-06, 10:18 PM
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Tilebri, just like you pointed out, I have been asked that slope question multiple times. Anyway, I don't mind answering that: I do have a slope with 2 inch per foot.

However, while I am planning to put on tiles, I do have another very important question that has not been answered in this forum.

I do know I have to use the modified thinset and use it to fill the gaps between two plat hardibacker covered with mesh tape. But how about the gaps on the corner? I left a 1/8 to 1/4" gaps each corner between walls and ceilings.

Do I need to fill the same thinset or use silicone/latex seal instead?

I have never done any tile works before. Please bear with me for another simple question. Since the backer walls are not all even, some area has up to 1/8" difference within 2 feet distance (I think the uneven studs behind the backer board were the reason of that), I may need to use the thinset to patch up. So while I lay tiles on such a thick layer of thinset, it may ooze up through the space between files. How should I take out these extra thinset before putting grout in the spaces?

Any advice would be very appreciated.
 
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Old 02-17-06, 12:47 PM
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Hobby - You have to tape and mud the joints between the ceilings. Use the same modified thinset you are using to set the tile. The best time to tape all the seams is when you are tiling. If you do it before, you may wind up with speed bumps that will create problems for you when you set the tile.

Its always best to get everything on a flat plane prior to tiling. Getting all the framing on plane before putting the cbu up would have been the way to go. I can't really tell from your description how out of plane it is. If it looks like its going to be a problem, you can screed thinset over the low spots, let it set up and then tile over it. If its only out of plane a little, you may be able to get it flat by adding some extra thinset to the back of the tiles as you set them. Keep in mind that most thinsets are good for only 1/4".
 
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Old 02-17-06, 04:59 PM
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Thanks Johnny. That really helps.
 
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Old 02-22-06, 08:22 AM
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Johnny, thanks for the advice. I just brought a bag of modified thinset from HD and going to do the patch first. Now I found one more thing that I need to get advice again.

There are gaps between new installed backer board and existing painted dry wall (1/8 to 1/4") on the area where this remodel shower meets the rest of the bathroom. Since the existing dry wall is finished with paint which is a little more than 1/2" thickness.

While these two walls meet, do I need scrash off the surface paint on the existing wall from edge of 1" so that I could use 2" fibra tape for the joint and also, I will get a even surface in this area since the backer board in the other end of joint is exactly 1/2" thickness?

If I need to do so, what is the best way (tool) to scratch the paint of the dry wall?

That bring me to another question: if I want to tile over a existing painted wall (not inside of shower but part of bathroom, which doesn't require backback by code), do I need take the layer of paint out before troweling the modified thinset?

Please bear me, a newbia. It sounds a lot of questions. But I do appreciate your input. As I alway said, I have learned alot from this forum.
 
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Old 02-23-06, 01:57 PM
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You should be ok taping the joints. You don't have to strip the paint. If the joint will be covered by tile, use thinset, if the joint will be painted, use dry wall mud (joint compound). If the paint is in good shape - not peeling off the walls - the thinset should adhere fine.

This is all outside the shower area - right?
 
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Old 02-24-06, 10:47 AM
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Thanks Johnny. I got it. The area is outside shower and I have to use the thinset to fill the joint since I plan to use the tiles to cover the joint and part of old dry wall.

Good to know I don't need to scratch the paint which would be painful process.
 
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