Hello, all
“Longtime (mag) subscriber, first time poster” here. Following Tom Meehan’s suggestions in FHB #141 (09/01) Installing a Leak-Proof Shower Pan I attempted a do-it-myself shower pan on a concrete slab floor. All went well until the final mud layer dried. I now have a very sandy surface which erodes as you run your hand or a brush over it. Obviously this is not a good surface for laying the tile, if I expect it to adhere!
Apparently I screwed up the mix of the mud somehow, or overworked it. Is there a liquid bonding material I could brush or trowel on to solidify the surface and make a good substrate for my tile?
Thanks in advance,
Neal
Replies
nope. jackhammer. I made my mix last week 60 sand 40 cement and its hard as rock.
FWIW, my tiler uses stuff she calls "float" for the layer on top of the liner. The bag says 5000, so I assume that is 5000 psi, and it's pre-mixed. Available at the big box places I think, and maybe the tile supply places.
I had same thing happen on my first one. Gently break it up with a hammer, so that you don't puncture the liner, remove all of the debris, retest to make sure everything is still watertight and then redo. I mixed mine a little stronger the second time, about 70-30 just to make sure I wouldn't have to go through the trouble again. Sorry that it happened to you, but look on the bright side, you will have the process down when you go to do your next one.
Brian
Ohhhh, man. . . that's not what I wanted to hear!
Can I have a little more info on this? The mud mix was a 60/40, and the pan is very solid, not crumbly (except of course for the surface), so what is likely to happen if I were to use something like a liquid concrete bonding material and let it set up before installing the tile? (Tile will be mud-set, if that matters)
By the way, at least I did place a sloped layer under the liner!!
Thanks,
Neal
Neal, I'm about three weeks away from doing the same project ... following instructions from the same article. I don't want the same problem, though, so I've been watching this thread carefully.
Why do you think the surface is crumbly? Would "overworking" it bring a too-high percentage of sand grains to the surface (not enough cement)? The article suggests a very dry mixture ... just enough water so that a compressed handful of the mix will hold its shape. Do you think a slightly wetter micture would have worked better. Sorry I don't have any answers ... just want to understand what happened. Maybe you continued "working" the bed after the portland began to set?
Allen
Allen,
Actually, I don't know exactly what happened. I am pretty sure I mixed it the same way as the layer under the liner, and it turned out fine. I did follow the "test" by ensuring that I could make a ball, but I do suspect that I over-worked it with the trowel, so maybe a little more water would have helped. It is not breaking up, and seems solid enough, but lots of sand on the surface. Guess I'll probably follow the advice I've gotten and chip it out. (Grrr!) Easier now than after the tile is in!
Neal
Neal,
If you're not in a big hurry try this;
Dampen the bed, then lay some wet rags, towels, or burlaps, on it. The rags should be rung out by hand as best you can. By hand. When the tops of the rags, etc. dry out rewet them. eep the bed covered this way for three days and see if the bed is in better shape.
Even after this treatment, if it works, there may be a very thin , just the top, layer of sand that still hasn't bonded. It it with a stiff brush and you will know in an instant. Or two.
In the future, the mix should be so dry that it crumbles as mixed. When you squeeze a wad hard in your hand, it should mostly stick together, but it's better if the large lump you squeezed breaks in two or three pieces.
Forget the trowel, it takes practice to use one properly on drypack. With that practice they are faster and look more professional. You need two specialty amatuer tools.
The first one is a 2x4 about 12" long. Dump your bedding mix in place and use this too to spread it around loosely. Make sure that you dump enough to be an inch gigher before packing than you think you will need. Using your specialty amatuer high dollar tool, spread the mix evenly, then pound the shid out of it till it's all firm.
The next specialty tool you will want is a length of 2x6 just short enough to fit between the drain and the nearest wall. Rip 1/8" off each edge to get sharp corners all around. This is your scraper. You can put a couple of knobs or handles on it to make it easier to push around.
Lay it flat on the bed and use it like a plane but push sideways. After you have scraped and cut the large areas down to grade, you can use a trowel to scrape or cut the edges and corners down. Do not "finish" the surface, finishing tends to make it impenetrable to water.
Now take some rags or towels straight from the spin cycle or just barely dampened, (no drips!) and lay them on the bed and cover with plastic weighted down with some more towels. Let set overnight.
This technique works for the sub bed and the tile bed.
good luck and have fun.
SamT
Hey, Sam,
That's some great advice! I sincerely appreciate you taking your time to give me the details. I will certainly try the wet burlap technique, and if it doesn't work, will follow your advice when replacing the mud.
Also thanks to all others who responded and who emailed me directly - certainly got more help than I anticipated.
Thanks again,
Neal
Whoa. Stop. Don't reach for that hammer yet.First of all, I like a rough sandy surface, and I don't want the surface hard as nails. This may sound counter-intuitive, but let me explain. But first I need to tell a story.I did my first shower about 10 years ago, having read Michael Byrne's book, where he suggested that the installer use an Ad Mix to the mud to make it stronger. I posted something on a BB and basically got the response that the Ad Mix wasn't necessary and the surface really ought to be sorta soft. I thought the guy was hick, and what did he know. So I added the Ad-Mix, and probably added enough to make it 3600 psi. I was going to be a Tile Stud, OK?The first thing I noticed was that the float was sticky and gummy, and stuck to the strike off. I switched to aluminum and it was still sticky. Well, I thought, whadda these idiots know, my floor is going to be 3600 psi!!!The other thing I noticed was that after being striked off, the float would sorta congeal, there would be high spots and low spots, and no amount of striking off, or pounding with a wooden float would level them. It was trying to sculpt with jello.The floor cured in record time, thanks to the Ad Mix and was rock hard. The high spots were still there, and were rock hard, and I had to chisel them out with a cold chisel and a large hammer to get it flat. The bird baths were there too, but could be filled in. Ultimately, the floor was such a mess after flattening with a chisel, that I SLC'ed it to flatten it.Neal, what you want IS a nice soft sandy floor. I don't damp cure it. I just tile it. And the advantages follow:When laying tile and you get a hight spot, (I still do, I'm not perfect), the highs can be shaved down with the edge of a steel trowel the next day, which is like way cool. Just take the edge of a trowel and shave off the high spots, and fill in the bird baths with a dab of diluted thinset. This is so easy, and avoids the friggin jack hammer which is what you will need if you get a rock hard damp cured ad mix surface. So I disagree with most of the previous posts.This is a friggin shower for Christ's sake, not a driveway. It has to support at worst, a fat guy wieighing 300 pounds. The tile is rock hard, and so long as standing on it doesn't cause the mud to crack and disinegrate, or running your hand across it, doesn't cause huge chunks to come loose, you are fine. The tile will stick (thinset sticks to everything) and it will be fine. I have never seen a sandy mud disinegrate, and indeed, I have demo'ed some showers built only on compacted sand that lasted like 50 years. So relax and take a deep breath and lets look at your floor. Maybe post a picture.I can't judge your floor. But run your hand accross it, and like I said, if chunks don't come flying off, or it doesn't crack and disinegrate when you stand on it, you will be fine. Like I said, I like a nice sandy surface. Counter-intuitive, but alas, that is tile work. Regards,
Boris"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
Boris,
Thanks very much - I appreciate your input - I'll put the hammer away now (and even better, I am at least 110 lb under your theoretical showering guy).
Thanks for taking the time for a detailed response, and thanks also to SUNTOAD and davidmeiland for the confirmations.
Wow, what a great board!
Neal
Another vote for what Boris said.
OK. If this is your setting bed--the most important thing is that it be flat and pitched a quarter inch per foot, minimum. Before you tile, take the time to take a straight edge and check for flatness, not level, but flat and pitched. Now is the time to fix that. Use Custom's QuickFix or some thinset and let it cure. But you want it flat and pitched, OK?Regards,
Boris"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
another question: Do you tile the wall or floor first
floor...
proud member of the FOR/FOS club...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming
WOW!!! What a Ride!
Doesn't matter.Most pros do the walls first, but that sorta muffs up the setting bed (but it can be covered with cardboard).I do the floor first for the only reason that the walls then overlap the floor, and I put dab of silicone caulk, or sanded caulk at that intersection. If it overlaps the water goes directly onto your well sloped floor.If you do the walls first, then the moisture goes into that gap, and will hit the membrane, but I think there is a better chance of moisture build up and wicking if the walls are done first. Added to the fact that the setting bed is protected with tile. This is not a big deal, though. Pick'em. Chicken or Fish. Ford or Chevy.Regards,
Boris"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
how do you do the corners, overlap the tiles or leave a gap
usually floor ...
sometimes walls ...
doesn't matter though ...
as the bottom row of wall tile is left off until the floor is done.
it's also left off until the wall is set ... as that's where the level ledger is set.
so .. that last row of wall tile the whole way around the bottom is the very last tile to be set.
Jeff
Buck Construction
Artistry in Carpentry
Pgh, PA
Flat: check
Pitched to drain: check
Actually, I'm just prepping this shower for a pro to do the tile - it will be thickset (walls and floor), and that takes more skill than this amateur has! I just wanted to be certain I was starting with a good base.
Thanks again for everyone's input.
(Incidentally, I haven't made a deal with a setter at this point, so if anyone reading this is in the Austin, TX area, knows how to do thickset, and is interested, shoot me an email. There's the shower and the b'room floor as well; I'm in the sticks about 30 miles north.)
Neal
In the "old days" we used to do our mud set pans in a mixture that would just make a ball when squeezed in your hands. That was when we were laying mud base floors with screed boards etc. Now I make my mud base showers a little wetter, lots of additives and not much troweling. You want a rough surface to adhere the tile thinset to anyway, so don't over-work it.
I have 2 showers built like this. I am wondering if there is a better way of getting the water to drain through the weep holes to the drain. It seems that since the liner is laid on flat concrete and the slope is built on top of that, there is always water standing. I'm thinking the weep holes have plugged.
the concrete under the liner needs to be slope too.
The idea is to pre-slope under the liner ( lot of the older plumbers, goofy from years of pouring lead joints, think this is nonsense, so I take over after they put the drain in.).
I usually cram some bread from a sandwich (one of my guys prefers potato bread, so I use his sandwich cause potato bread is pretty puny) into the weep holes before laying the tile bed. If the moisture doesn't get the bread, the cooties will. Never had a problem with one yet.
Edited 2/2/2005 8:56 pm ET by Notchman
Sounds like my builder screwed me on yet another thing. So would you build a pre-slope and then put the liner in and then add more mud for a surface to tile on? I already had one rebuilt. It started leaking the 1st week we moved in. The tile guy forgot to secure the corners of the liner and the fold fell down even with the floor. Water just poured right out. It sounds as if I will be redoing the others in a couple of years. Thanks for the info.
Get yourself over to the John Bridge Tile forum at JLConline.com.
There you will find step-by-step instructions with pics and about 10 moderators who are tile guys during the day. They will help you through this. They don't even snicker. Honest.
ShelleyinNM
I use Noble Company's products for all my shower pans. Instead of making my own pre-slope on the last shower pan I tried "Pro Slope". Check it out. Easy to install, a perfect 1/4" slope and saved me time. http://www.noblecompany.com/proslope.html"One measurement is worth a thousand expert opinions"
No matter what the sub floor is. First step after the drain is in place is a pre-slope to the drain. Then the liner on top following the slope to the drain. Test the drain and the liner with standing water. The idea is to make a large funnel for the water to flow out of. On top of the liner goes the wet bed for the tile. This way any water that gets past the top wet bed and tile ends up in the drain. Sounds like you missed a step. Last summer pulled out a large shower without the pre-slope rot and mold and leaks and standing water in the liner. Real nasty!!
I'm no expert, but I do understand that porosity is inherent and desired in the mud base. Ergo me thinks vacuum off the really loose grit and the thinset you use for the tile will bond wonderfully as it is.
Let's not confuse the issue with facts!
Boris is right on.My first shower gave me the same worries (a sandy surface after curing). But the bed was hard. Just a softish, sandy surface. I brushed it off and tiled over it anyway. My worries were unnecessary. The shower floor turned out great, and since then, like Boris says, I find I prefer the sandy surface. And the tile WILL stick, and (unless you drive a truck over it), it won't fail. Don't worry. Tile it. Be happy.
Here's another vote for a sandy surface. I use deck mud from sacks, rather than mixing it myself. It does not set up like concrete. If you sweep it or rub it with your hand you get some sand. I vacuum it and then set the tile.
Just brush back and vacuum any large loose grit and run a coat of thin set mortar on top and it will fix any adhesion