mud bed cure time with waterproofing [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile

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jwmezzanotte
04-04-2011, 12:38 AM
Looking for info on mapeilastic hpg or kerdi over a sloped mud bed. Specificly cure time before installation. Ive tried searching, but only found one random reference to 72hrs, something along those lines.

Are these products compatable with a mud bed shower base? If so, what length of time is required for a mud bed to cure before the mapeilastic or kerdi can be applied?

Mapei also sells 4-1 sand/cement mixture for mud beds. Would this be a good product to use, or should i just make my own 5-1 (or 4-1) mix with sand/portland cement?

Would mapecem premix be a better product to use to make a shower pan with slope and then covered with mapeilastic? The mapecem info states that it can be used to make shower slopes, and can be tiled within 4-6hrs and other flooring can be installed in 18hrs. Would this mean an 18hr cure time before installing mapeilastic or kerdi? I plan to continue using kerdi drain with either the mapeilastic or kerdi, I feel comfortable with it.

I'm just trying to find a system that i feel comfortable with for building shower bases using products that we have (can get) locally. I'm from a small town, 3in common nails arent quite "we can order them for you" here, but almost.
thanks for any help
John

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bbcamp
04-04-2011, 05:24 AM
The three Malelastic products I looked at call for the mud bed to be "cured." One of them further defines that to be "at least 3 days." That sounds reasonable to me.

Mapei's 4:1 mud mix is fine if you'd rather buy something ready to use than mix yourself. If you do use it, be sure to fully dry mix the product befor adding water.

I don't think I would recommend Mapecem for your preslope. Fast curing and DIYers are not a good mix. Another thought: curing and drying are two different things. Just because the concrete is cured, doesn't mean it's dry enough to apply a liquid membrane.

What I do recommend is making a mockup of your shower so you can practice using the materials you select. I also recommend you obtain a wet film thickness gage to determine you have applied enough of the membrane.

jwmezzanotte
04-04-2011, 09:54 AM
Thanks for the response!

I wouldnt call myself a diy'er, I'm a journeyman carpenter I've spent several years working as a cement finisher on a variety of projects, small pads, driveways, and worked on a few fairly large slabs. I've been installing tile for over 5 years now, getting better with experience id like to think..:scratch: Not at all saying I know everything or even close (thats why I'm on here) But I'm not new to cement based products.
I'm not concerned with the workability of fast curing products, Ive worked with a few before and I can move my ass when i need to. I've built well over a dozen showers in town (i guess i should keep track of this) none of which have ever had any problems to date.

The problem I'm having is that in this small town we have a few "experts" that have been doing the majority of the tile work here for years. They are set in their ways, which wouldnt be so bad except that their "ways" are all kinds of wrong.
They "dont need" waterproofing membranes, that orange stuff (schluter) "is garbage!" "yes, the rubber membrane sits flat on the floor like that, and no it doesnt matter that the drain is higher than the rubber membrane as long as the subfloor doesnt get wet", also "what's epoxy grout?" "sometimes tiles floors just crack, its normal take your chances." and my personal favorite "grout just gets moldy, its not my fault. thats why your "supposed" to use dark grout, so you dont see it" :bang:

Its also the norm around here to have varied size of grout lines (tiles arent all the same size. uh-huh :rolleyes: ) corners of tiles pointing up or down after being installed "because the sub floor was no good", I guess nobody has ever heard of fixing it??? frustrating.
These experts are :gerg: and Italian, so obviously they everything about cement and being younger and of different opinion I must be out to lunch! Its really frustrating here to explain to people that no, tile floors dont have to "just crack sometimes" and no, tile showers dont "just get moldy". Ive run into a few jobs where I've explained the kerdi shower system to people and heard "xxxxxx said that you dont need that "garbage" are you sure you know what your talking about?":bang:

Anyhow (kinda went on a rant there)
I've used the kerdi shower pan before, but I dont like the idea of having a foam shower base. I'm comfortable with the kerdi product, but after using mapeilastic on a couple jobs I've started to prefer it, I like not having to deal with the build up of the kerdi corners.
Ive made a reinforced concrete base before. Used the kerdi drain as a form in the concrete, when the concrete had set up i pulled the drain out, cleaned it up, and re-installed it in a bed of thinset (glueing the drain to the trap as well at this point obviously). Afterward I went ahead and applied kerdi to the shower base and walls. Although this did work and worked well for me on a couple of jobs, It didnt allow for 28 days of cure time. Those showers i did are now a few years old with no problems, but not the way I'd like to continue doing things.
Ive done a couple showers the same way but using masonry mix, also with no problems to date, but again not having the proper cure time.

On the last job i was given advice by a mapei rep to use a fast cure masonry mix type product (cant remeber the name at the moment, but wasnt a mapei product. Which i thought was strange coming from a mapei rep, but whatever) and wait 24hrs before applying mapeilastic. I applied mapeilastic with a v-notch trowel and then bedded mesh on the base and then rolled it out. The next day I applied a second coat and coated the walls. This worked out quite well also, except for one problem...
The masonry mix product i was advised on was HORRIBLE to use to make a slope! I mixed it really dry, not quite drypack, but close. I dumped it out of the pail and it spread like slc, even being mixed dry like that. It took quite a bit of patience to set the slope i needed.

Ive been "trying things" for a while now. So far never having problems or any call backs (although given that people think moldy showers are normal in this town.....) and I'd like to keep it that way.
Just looking for a system that i can stick with for a while.
I like the 5 to 1 mix and feel comfortable with using it, just need to nail down an actual cure, or drying time that it needs before installing either kerdi, or mapeilastic. thoughts?
This is the only reason I'm considering using the mapeicem premix. Because it states the cure time. I dont want to be waiting 28 days, and neither do some of my customers that seem to beleive i dont need that "garbage" (waterproofing) anyhow.
Sorry for the long post! Just trying to explain myself.
thanks
John

bbcamp
04-04-2011, 10:16 AM
I like the 5 to 1 mix and feel comfortable with using it, just need to nail down an actual cure, or drying time that it needs before installing either kerdi, or mapeilastic. thoughts?3 days. 4, if it is cool.

jwmezzanotte
04-04-2011, 10:38 AM
thanks. thats around what i was thinking, just wanted to have it confirmed