Hardibacker and shower pan

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Old 12-26-13, 10:10 AM
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Hardibacker and shower pan

I am in the process of adding a custom shower (over concert slab). I have the old stuff removed and the bathroom is down to its studs. I installed 2X8 around the shower area to support the membrane and shower pant. After laying the membrane against the 2X8, I was planning form the pan. However, my contractor mounted Hardibacker boards against the membrane (screwed to the studs and did not penetrate the membrane) then he made the pan. Now the pan is setting in hardibacker surrounding then the membrane. Is this acceptable? If not, should I start all over? Or can I save the existing pan by applying Readgard over the pan and the hardibackers?
Thank you for your help.
 
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Old 12-26-13, 01:07 PM
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How to build a shower - Building a shower pan with pre-sloped mortar bed, liner and curb.

Look at the pictures in the attached link to see if the contractor followed the same procedure on the hardi and the pan membrane. Your post is a little confusing, but if I deciphered in right, you should be OK. You do not want any screws to penetrate the membrane as it should be a waterproof pan without any breaches. The sloped mudbed packed into the shower floor will hold the hardi tight to the wall studs and act like nails once it hardens.
 
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Old 12-26-13, 01:32 PM
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Thank you for the quick reply and feedback. My contractor used similar principle to build my shower pan. As on your pictures, the hardibackers were imbedded in the pan (however he did not allow for a gap at the bottom of the boards). I am concern about the hardibackers getting wet constantly. If you have few minutes please check this video: Shower Pan Tear Out - YouTube
(Shower Pan Tear Out - on youtube).
Also, my guy built the shower curb from 3 - 2X3 greenwood, folded the extra membrane on it, then added the backers (sides and top)
 
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Old 12-26-13, 02:36 PM
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I think that there were additional issues with the shower in the video. Mainly, was the use of grout in the corners and not flexible caulk. That one corner shot they panned across showed quite the gap from cracked grout which is a direct route for water to get into the areas damaged. It also did not look like they taped the corners of the hardibacker. I personally use 1/2 durock for showers and not 1/4" hardibacker. I think the lack of a pre-slope (or use of a double slope) with the pan liner sandwiched was also a key issue. Water would seek the low spot in the shower instead of being channeled toward the drain.

Explain what you mean when you said that they added the backers to the curb? I don't have an issue with the thickness of the wood so much as the addition of screws and or nails to the membrane on the top of the curb. If I don't use wire lath and create my own bed on top of the curb, I get a pre-formed curb that fits over the membrane and wood (upside down "U" shape) and then nail only from the outside of the curb.

Can you post a couple of pictures of the progress? http://www.doityourself.com/forum/el...-pictures.html
 
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Old 12-26-13, 06:30 PM
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Thanks again...
Definitely the shower had many other issues which caused / accelerated the leakage and mold problems.
Adding the backers to the curb, I wanted to say: 1- After laying the membrane on the floor and 8 high all around. 2- He placed and screwed the backers to the studs. 3- he started the screws 8 high from ground but the backers were all the way at the bottom of the membrane. 4- Then he formed the pan which was inside a hardibackers box (kind of). Please see attached pictures
I am not an expert but based on my understanding, the membrane is in place to collect water penetrating from grout lines to the drain. If the backers are inside the membrane then they will continuously get wet and I am concerned that backers will crumble
 
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Old 12-27-13, 07:13 AM
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Scratching my head why they patched the bottom portion of the cement board instead of starting with a full sheet and patching the top half. The bottom has the shower pan membrane behind it which adds some dimension to the wall. There is now a bump-out between the two sections unless he shimmed the top part of the studs to the same thickness.

Again, not crazy how he did the curb, but ask him to spread RedGuard on top of everything before he tiles. That includes the walls and corners. Did he use any kind of a vapor barrier at all? Looks like an exterior wall - did he put any insulation between the studs? Where is the rough-in's for the plumbing?
 
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Old 12-27-13, 09:49 AM
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Yes, vapor barrier and insulation were installed. The roughin plumbing are in but not showing in the all picts. Do think I can save the pan and backers by applying redgard? Or is it too risky? I do not want redo the work 2 or 3 years from now. I though making a small experiment, after applying the redgard, I will block the drain and fill the pan with water. I will mark the water level to check if any seeping may accrue.
 
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Old 12-27-13, 12:14 PM
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Reviewing the redgard website, it says it is approved for pools and spas, but not as a finish surface. It also states to not use as a expansion joint fill. So, coating the floor, walls and complete curb will help, and I would add flexible sealant to the inside corners and where the wall meets the floor. That should provide a pretty good defense against what we saw in your video post. Don't go cheap on the sealant for the inside corners, I'm tempted to say go with a gutter sealant as it is proven to work in wet locations (Geocel - can be found at roofing supply houses). It will be under the tile and not accessible for future maintenance. You will double up on this by using color matching flexible caulk after you install the tile. The redguard will also add a benefit of mimicing a secondary slope to the pan liner, or more accurately, will act as a primary pan liner with the actual as a back up. Kerdi membrane is also a follow up but will probably be more pricey.
 
 

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