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Unread 07-25-2014, 02:34 PM   #46
Jim Cordes
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Dave, generally if you have one guy mixing for you while your working the mud after the first batch that you mix together(demo) he should pretty much stay caught up to you..more or less.
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Unread 07-28-2014, 01:59 AM   #47
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Thank all for the comments. This is a solo job so I'll probably pre-mix wet in several bucket batches with slightly more water than my 10(s):2(c):1(w) mix (maybe 1.5w) to give myself a bit longer working time. The 1(w) mix is quite dry (like the posted descriptions) but material not packed within 15 min no longer wants to pack very well. I'm assuming the top layer may actually be easier in some ways than the thinner pre-slope. First must finish the membrane and leak-test phase so I'm not needing to rush things. Glad I don't need to make a living at this ;-)
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Unread 07-28-2014, 09:04 AM   #48
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Dave, you absolutely do not wanna add more water to your deck mud mix in hopes of making things easier. It'll be just the opposite.

I would recommend you go to Contractors Direct and purchase a Bucket Mortar Mixer.

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I then recommend you dry-mix enough mud to do the job plus at least half a bucket more and stage those dry-mixed buckets near the shower. Add water to the first two and mix (takes maybe a minute per bucket). That will give you a good idea how much water you need for the remaining buckets and you can have pre-measured water for those.

Spread slurry. Place mud. Mix mud. Spread slurry. Place mud. Repeat as necessary. You'll find it works out rather smoothly.

I work alone about 99.9 percent of the time and use that proceedure successfully. The bucket mixer makes life sooooo much easier.

My opinion; worth price charged.
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Unread 07-28-2014, 05:12 PM   #49
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Aha! The answer to my query about sequential wet-mix of premixed dry in buckets vs pre mix wet in buckets. Thanks; the formula is becoming more clear.

Version 3:
- Mix ratio: 10 sand : 2 cement : 1 water -- never mix wetter
- For larger quantity, pre-mix-dry with known volume (so added water is known)
- Wet-mix a batch and place - always thicker than wanted
- Pack down once - down to a little above 'the line' - edges first
- Screed flat to match required slope
(If surface too low, scrape out the pack and do over -- don't add mud)
- Mix next batch and repeat.
- Once screed is accurate, trowel to smooth surface

Does this match the requirements better?
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Unread 07-28-2014, 05:19 PM   #50
Jim Cordes
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sound about right, all your batches should be pre-mixed dry that way you know they are mixed good. Do as CX said about the batches.

Also you should have more time then 15 minutes per batch..it should be more like at least 30 min or more before it dries too much, by your self you will be busy keeping up but you should still be safe with time..even if you mixed them one at a time it can be done.
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Unread 07-28-2014, 09:41 PM   #51
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Dave, you're not gonna know how much water to mix in your batch until you've mixed the first one. The moisture content of your sand will make a significant difference in the water requirement.

Have you reviewed the article titled Deck Mud in our Liberry?
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Unread 07-28-2014, 10:01 PM   #52
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CX, True, the moisture content can vary (as with humidity) but the sand is all dry packaged sand and the ratio of 10(sand):1(water) clearly suggests that humidity variations will only account for a very small fraction with dry packaged sand from HD. For sand from an outside yard, I'd agree. Cheers.
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Unread 07-29-2014, 08:17 AM   #53
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Hmmm..... It ain't dat complicated.....
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Unread 07-29-2014, 11:38 AM   #54
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When I did my pre slope I mixed one bucket at a time.

I started out at the walls,once I had the proper depth and all sides were level I worked towards the drain checking the pitch.

It was a slow process mixing the mud by hand.

Looking back I should have had a helper mixing or the Bucket Mortar Mixer.
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Unread 07-29-2014, 06:23 PM   #55
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Like CX said the water will vary..porous sand just in itself can effect that. no written in stone amount of water will work for all conditions and types of sand.

And I have found, as I suspect many other guys have found, that sand and cement ratios also seem to change depending on the sand. so hence you start to see why many long time mud guys don't really have a set formula they use everytime.
It is a feel that you learn over time, it is not that mud guys are lax in the way they mix, it is that they adapt the mixture for better working mud. and many times this means the first batch ratio might need adjusted for the next batch.

Can you see why that after thousands of years of deck mud that no one has a prefect formula. I would worry less about finding the perfect ratios and more on how to change change the formula, on the fly, to get it more workable...ex. more sand next batch,more cement next batch, more/less water next batch..not a perfect way but the best we can do with so many variables.
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Unread 07-30-2014, 02:04 AM   #56
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Jim, agreed; there are enough variables but IMHO (where each project, like this one, has sub-projects which are new, it's really nice to have a starting point that is close -- like when using dry bagged cement and sand, the sand:water ratio that might be a little dry rather than too wet. When you don't have a natural feel for it from year of experience, a hint is very helpful.

Just did a thinset skim-coat of pre-slope #3 improved the surface (except for the thinset roughness in placed - needs a bit of scrape or sand) and, I think, close to flat. Checks with the level show a little variation but always downhill.

Once the thinset is cured, I'd thought about gently pouring water on the surface in various places as proof there are no valleys. Is this likely ok for the thinset skim-coat? Just thought it might be good to know of any residual surface flaws before installing the PVC liner. If I found a slight dip, can I just fill-in with more thinset? Thanks.
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Unread 07-30-2014, 02:21 AM   #57
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No need to test on bare cement,no need to trap water under the liner,and absorbant cement might not tell you anything anyways.. go ahead and install the liner, then test it for drainage and do a flood test. If it fails the liner can always be pulled back up and low spot fixed. You should be alright though if you checked it good with level.

Need help on liner? remember to use a bead of silicone on the underside of liner at drain,none on top. fold all corners with no cuts, three inches above curb,recess wall studs to allow for liner, nail on outside of curb ONLY. pre-bend metal lath to fit over curb with tail going into pan for the second mud bed to stick to..again only nail on outside of curb
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Unread 07-30-2014, 08:22 AM   #58
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And when making the folds at the curb, put the "ears" on the curb side, not the wall side. This way you can bury the folds in the fat mud going over the curb. Pictures start at post 116 for this http://www.johnbridge.com/vbulletin/...=112055&page=8
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Unread 07-30-2014, 07:00 PM   #59
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I sometimes leave a space between the wood curb and the wall studs and shove the ears in it,,same with inside corners..leave the studs gapped and shove it in there..makes for a neat job.
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Unread 07-31-2014, 11:26 AM   #60
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The OP is back – someone really hijacked my thread That's ok - lots of good discussion.

I realize I made a mistake in my first post. When I said I added 6 cups of water to the 60 lbs of sand topping mix plus 25 lbs of play sand, I didn’t think about the size of the “cup.” The “cup” was actually a plastic drinking cup that holds about 12-14 ounces (I don’t remember if I had it full to the brim when I added the water). So 6 “cups” would have been about 70-80 ounces of water, or a little over half a gallon. Based on other posts in this thread, regarding the 10(s), 2(c) and 1(w) ratio, I think the water I added was about right. As I mixed the mud, I added one “cup” of water at a time and mixed it thoroughly until the mixture looked and behaved just like what is described in the dry pack article in the “liberry.”

I tore out the floor and I am going to redo the pre-slope layer. I have been working on other stuff and haven’t done the second try yet – that is a project for this weekend. When I tore out the floor, it came out very easy. I didn’t use thinset on the concrete slab, so the dry pack wasn’t stuck to the slab at all. I didn’t have to chip it out. I dug a putty knife into the loose parts, all the way down to the slab, slid the knife under the dry pack and lifted out big chunks. Some of it came out in good sized chunks, and some of it was dust and I had to sweep and vacuum it out.

John Bridge’s article mentions that he has no trouble achieving 3000 psi compressive strength with this very dry mix. Much of my floor came out as dust, with obviously no compressive strength at all. Even the parts that came out in whole chunks are very soft. They are over an inch thick but I can break them in half easily with my hands. If you drop anything on them, they crumble. The whole pile of debris has been lying on my garage floor since I tore it out, nearly 3 weeks ago, and it is still as green as the day I poured it.

What bothers me the most is that I am not certain what to do differently on the next try. I followed the instructions on this forum, and the mud behaved as instructed, but I still think I used too little water. Plus I think the slab sucked the water out of the dry pack. I dampened the concrete slab before laying the mud, but I didn’t use thinset. I also probably worked with the material too long. By the time I was finished with a section, it had definitely dried out, and I don’t think it would hold its “snowball” shape any more. The only thing I can tell I definitely did wrong, based on instructions on this forum, is that as I packed and screeded the floor, I added thin layers of additional material to fill in low spots.

When I tore out the floor, there were two places where the pack was strongest and where it came closest to bonding to the concrete slab. The first place was the first place I dumped in mud, so it would have been the wettest. The second place was the last section I worked. My wife mixed new material as I worked on the floor, and on the last batch, she added 7 cups of water instead of 6. So all this still makes me think my mix was too dry.

So when I try it again, I am going to use a little more water, I am going to trowel down a layer of thinset on the concrete slab, I am going to work faster, and I am going to pack it all in once, then screed, and not add any new material. Hopefully it will work better this time.

I have some unrelated questions about tiling the walls.

The shower walls to be tiled are covered floor to ceiling with Hardie Backer 500. I didn’t put any moisture barrier on the studs before installing the hardie backer. The cement boards are screwed directly to bare studs. Before I found this forum, another “expert” told me I didn’t need moisture barrier, and he said there are actually reasons why it is a bad idea. So was this a serious mistake? Do I need to take the boards down and put moisture barrier over the studs, behind the cement boards?

Also, I bought Laticrete Hydro Barrier and their anti-fracture membrane fabric to seal the cement boards at corners and niches. I have never used this stuff before, but it seems like an easy-to-use product. I have reviewed the installation instructions and the videos on the Laticrete website. I hadn’t planned to paint the entire surface of the boards – only the joints and corners. Also, the instructions for Hardie Backer don’t require the entire surface to be waterproofed. But then I thought I might as well paint the entire surface, and that could also offset the fact that I didn’t put moisture barrier behind the cement boards.

Since I have never used the Hydro Barrier before, I did a test and painted a scrap piece of hardie backer. I am a little concerned about covering the walls with this stuff and then expecting it to bear the full weight of all the tile, since the tile is glued to it instead of the cement board. After it dried, there were no bubbles or holes, wrinkles, or loose spots. It looked nice and smooth and ready for tile. Out of curiosity, I scraped at it with my finger and some tools, to see how firmly it was bonded to the cement board. When I scraped at a corner with a knife, I was able to raise up the corner, and then I was able to peel off the entire sheet in one piece. It didn’t seem like it was bonded that well to the cement board. I know that nothing will be peeling at the corners with a knife once the tile is installed, but I would have preferred that it was harder to peel off.

Questions:
• Is there a problem painting the entire surface of Hardie Backer with Hydro Barrier before setting tile?
• Do I need to take down the cement boards and put up moisture barrier, or will the Hydro Barrier be sufficient?
• Should I be concerned about being able to peel off the Hydro Barrier?


Thanks,
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