I was wondering what you tile guys use for cement in a shower floor mortar bed application. I have a tile supplier hear near me that sells a specific “thickbed” mortar for that exact use but it’s alittle pricy. I know that you can mix your own from dry ingredients but I only have a small shower to do. I didn’t know if there are alternatives to the more pricy stuff my supplier sells. Also I’ve heard from some people that they just use regular Quickcrete but that to me sounds sort of iffy. Please weigh in with your thoughts.
Thanks!
Mark Barnhart
” If there is one secret of success, it lies in the ability to see the other persons point of view as well as your own”-Henry Ford
Edited 10/7/2002 6:35:09 PM ET by Barnee
Replies
Deck mud is made by mixing roughly one part portland cement to six parts sand and approximately one part water.Deck mud should be rather dry and crumbly in consistency.
From 'Setting Tile' by Michael Byrne
what the heck
was I thinking?
sand mix, get it at home cheapo.... and expanded wire lath.
listening for the secret.......searching for the sound...
Hmmm. I start with a 6' diameter, depends on the number of people who will be in it at one time, hole 3' deep. Double sandbags positioned a foot or so away from the edge with a 2' gap for easy entrance. While some will not agree I go with firing stakes 10-12' away in all likely directions. If you want to go high dollar line the hole with corrugated iron, add a sump, increase the depth, and add a vestibule with overhead. A canvas sun beater can be added and makes the installation quite homey if a bit rustic. If experience holds there might be a few variations. ;-)
Personally I like to add a camo net which can be yanked back very quickly upon call for fire (also good for shade). Other than that I wholeheartedly agree.
I buy mine pre-packaged from DalTile or othe masonry suppliers. The ratio is roughly 5 or 6 to one. The water measure can not be set. It depends on the type of sand and its moisture. It must be mixed very very dry.
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1927
The old world guys that I used to watch when I was a carpenters apprentice 25 years ago used a lead "safe" liner for the bottom of a shower (now you would use the PVC or EPDM type) and then placed a pea stone mix or a sand mix as a base. The pea stone mix would be stronger. They also used sand mix on exp. wire lath on the walls and ceiling. These showers lasted a very long time.
I believe that you want the base concrete to be as dense as possible to limit the ingress of water as this concrete would have difficulty drying because it is essentially encapsulated by the liner below and the tiles and grout above. You can make a very good strong and dense base mix by taking regular portland pea stone mix and enriching it with a shovel of portland cement and several cups of a superplasticizer if you have it. The super P will reduce the amount of water you need to add.
With all due respect, I would not use pea gravel or a sand mix. I would stick with DeckMud. The Tile Council has very specific mixtures specified and neither pea gravel nor sand mix are one of them.
The problem with both is that gravel is not as stable as Deck Mud and if walked on might put a hole through the pan membrane. Us tile guys do use gravel around the weep holes in a drain to keep them open. I have also heard of spreading some very fine pea gravel on top of the membrane topped with Deck Mud, to help the setting bed dry out. This same technique is used in exterior tile jobs, but we use a product called TROBA from Schulter. I have used it a couple of times in commercial heavy use showers. It goes on top of the membrane and under the setting bed and helps the setting bed drain, whereupon the moisture goes out the weep holes and down the drain.
The problem with sand is that it may shift and one needs a small amout of portland cement to keep it in one place. Hence the 5-1 ratio of sand to cement in traditional Deck Mud.
Lead pans are a tough install unless they are shielded from electrolysis to cast iron waste pipes. They will also react to acid in shampoos. I think PVC or CPE are better choices.
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1927
I may be in trouble. My tile man uses a 2 to 1, sand to Portland cement mixed very very dry. It appears to work quite well, but I have not had any time exposure yet. Several posts indicate sandy mixes of 5 or 6 to one Portland. Does anyone know if and when I will have problems?
Your mix is a bit "rich" for deck mud. Any problems you will have will be in shrinkage (apologies to Seinfeld).
Portland Cement will shrink when wet, due to the fine particles of lime and cement, etc. Sand, of course, has very little shrinkage (that is why they use it for compacting) when wet. If there is shrinkage, then part of the floor may sink (low spots) or may contract from the walls (gaps).
This is not a big deal, and can be easily remedied by using a tile patching compound, like Custom's QuickFix and Mapei's Plani-Patch.
The other problem will be with workability. The typical deck mud is very granualar, and after drying high spots can be easily scraped off and the whole float "worked". A rich float with lotsa cement will dry very, very hard and will not be able to be worked when setting the tile. This may seem counter-intuitive, but one honestly wants a fairly low strength floor in terms of psi (1800) for the typical tile job. We are not building bridges or garage floors, they are bathrooms for stocking feet. And workability is a nice feacture to have.
I know of no way to make a float more "workable" once it has cured and cured hard.
Subject to the above, I think you are fine.
Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1927
Hi Barnee,
I found this for you
The Secret to Good Deck Mud
To the untrained eye, properly mixed deck mud looks like it's far too dry to be of any use. Most tradespeople assume that deck mud should be plastic and pliable — similar to brick mortar. But good deck mud should have just enough moisture to hold the mixed ingredients together when squeezed into a ball. This stiff consistency allows the mortar to be tightly compacted, which is critical for tile floors.
The working characteristics of deck mud also differ significantly from other types of mortar. You may "carve" (rather than trowel) deck mud to final height, using the lead edge of a wooden float.
Students at our classroom facility in Clemson, S.C., are taught to test their finished floor setting beds by standing on the bed immediately after it has been floated and finished smooth. If the setting bed is mixed and compacted properly, the fresh bed should not show any heel marks after it's been walked on. Setting bed mortar contains two ingredients: Portland cement and sand. An acceptable mix
consists of four to six parts clean, sharp sand to one part Portland cement. Sharp sand particles compact better than rounded ones. Mix the deck mud in a large mortar box. Place all the sand in the box, sprinkle some water on top, and use a mason's hoe to pull the sand back and forth to lightly coat the particles with water. Add the Portland cement and pull the mixture back and forth until it's thoroughly mixed. Finally, add just enough water to achieve the required consistency, then mix it thoroughly again. A liquid latex additive can be used (not necessary) to improve the performance of the deck mud. When using a latex additive, always follow the manufacturer's proportioning and mixing instructions.
Note: to avoid or minimize shrinkage the resulting base should be wet cured for several days. On such a small base and if the mix is dry you should not get any noticeable shrinkage.