mud mix

[mondo]

is it ok to use a 3 part sand 1 part portland for the mud or is there a down side to making it a little richer then the normal 4-6 parts sand to 1 part portland.

[davem]

It will be stickier and harder to pull. It will also be harder and stronger which is not necessarily a good quality for deck mud.

[mondo]

davem
why would it not be good for the deck mud to be harder and stronger?? not as flexable???
i was thinking that the preslope will be down to 1/2 an inch around the drain and the richer mix would hold it together better, but my thinking might be wrong!

[davem]

Your half inch at the drain will be fine with standard deck mud. I don't know if flexible is the best word, but yes that's the idea. You don't want movement in the subfloor to translate to a "crack" in the mud the way concrete would crack.

Plus as Scooter has mentioned before many times, if there are any high spots in your mud, the softer mud is easier to correct.

All that having been said, some guys use quikrete sand mix (which is about 3:1) straight out of the bag without adding sand and don't have problems.

[mondo]

davem
thanks for the info.
i went to your, built a shower with the help of TYW. i just finished insulating today but before i put the plastic up i was going to slice the vapor barrier on the insulation so as not to have one on top of another. i couldn't tell from your pics if you did or not. any thoughts on that. thanks mondo

[davem]

Didn't do it, probably should have. Next time.

[Scooter]

Leme give you the wisdom of my direct experience. I am not a full time tile guy, just a dumb remudler, so take this with a grain of salt.

About 5-6 years ago, I read Michael Byrne's book and noticed that he recommend using Acrylic Ad Mix to make the mud stronger and harder. Wow, OK, having a 3600 psi mud floor made sense to me. I posted something here and John chimes in and says that his mix is sandy and he doubted that any of his floors are much above 1800 psi. OK, I thought, he's some hick from Texas what does he know. I've read MB's book, and well, I know better.

OK, so I fire my tile subs and try my first floor. I make the mix rich like you wanna do, and to boot, throw in some Ad-Mix. This baby is going to be 4800 psi and we can drive a car across it, OK? I am feeling really good here, OK?

I float the floor and the first thing I notice is that the mud is sticky, and clings to the strike off (straight edge), so I switch to aluminum and it still clings. No big deal, I say. I also notice that because it is sticky I am getting some humps and dips that just won't strike off. The mud clings together and it is like trying to sculpt with Jello, OK? Thats OK I say, I am still a tile stud.

Well, the floor dries and what a mess. The humps are rock hard. Yep, 4800 psi. You couldn't shave them off without a frigging jack hammer. So I have to chisel out the humps and fill in the dips, and spend a solid day fixing up the floor, and it still wasn't very flat, so Level Quick and Quick Fix was the ticket. Ugh. I felt really stupid, and was.

So what you want is very counter intuitive--a sandy loose floor that is fairly soft. It will be flatter because the mud won't cling like Jello. If, God forbid, there are humps, you can shave them off the next day with a flat trowel, not a frigging jack hammer. Dips are easily taken care of with some thinset or QuickFix.

Well I'm on the program now. I threw away the Ad-Mix and now am on the 5-1 program. More sand, less porland. Less is more. Actually the pre-bagged stuff at the masonry store or DalTile is great. Probably 5 or 6 to one, because sand is cheaper than Portland.

I am now a recovering Ad-Mix Portland holic.

[Davy]

I agree, I make mine 5 to1 also and without admix. Another thing is the mud under the shower floor tiles needs to be porus, you want it so water can run thru it and make it's way to the weep holes. A mud bed that's hard as concrete won't do that and water tends to wick up the walls and up over the curb from it. Pretty much makes the weepholes useless.

[mondo]

scooter
reading your reply made me laugh, thanks for that.
i get alittle carried away sometimes.
i took 3 empty cans of tuna fish and made 3 different mixes, all 3 to 1 but one with admix and the expensive med sharp sand,another one the same with out admix and the last one with fine sand. of course i had lath in the bottom of the cans, let them cure for 5 days in water and then cut the cans off. i was dropping them from 5 ft onto concrete and not a scratch. it wasn't till i beat them with a hammer that i got them to split. i thought you were suppose to be able to drive a car across it! but i get your point and will mix with more sand. especially in the above the membrane mud and no admix. i've also read Michael Byrne's book
thanks

davey
what you said makes good sense. now i know what we want the morter bed to do. thanks

i'll be mixing mud in the morning. mondo

[mrosspa]

There are a number of thing that MB likes to recommend in his book: roofing cement under the CPE, admix in the deck mud. I'm really glad I didn't do those things.

Scooter, you've given me the best example why sandy is better.

[william keller]

scooter thanks for the laughs they were great. and some very sound advice.

[T_Hulse]

Scooter that's an excellent reply & I've often wanted to say about the same thing but didn't have the energy to type it all. So if you don't mind I'm going to add your post to the Shower Construction Info thread in our Liberry.