mortar bed curing [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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02-03-2003, 10:29 AM
If you use portland cement and sand mixed by hand, can you tile the next day or do you have to damp cure for weeks?. What do the pro's typically do for large floor installations? Do they add an admixture or not?

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02-03-2003, 10:47 AM
You can walk on it the next day. I like to cover with with brown kraft paper (not poly) and wait about 2-3 days before tiling.

I used to use admix, more out of habit, but the more floors I do, the less I feel it is necessary. The admix adds strength; thats good and bad. Good, yes, it is strong hard substrate. Bad, because the bed loses some "workability" which has become important to me.

I am not a full time tile guy, just overgrown carpenter, and thus my floors are not perfect. There might be a dip or high spot here or there. If the floor is admix rock hard, I might spend a hour with grinders, chisels, QuickFix or in extreme cases, and SLC flattening out the setting bed. If the bed is workable, I can level the high spots with a frigging margin trowel.

I think if the area was a high traffic weight bearing area, I would change my mind and use the admix, but for the average bathroom, nah, I wouldn't use it.

02-03-2003, 10:59 AM
that's what i hoped as the premixed mortar is $20 a bag. I wouldn't have even thought to ask this question except that I noticed in Byrne's book he says to wait 28 days damp curing the whole time. I cannot imagine professional mud men doing this on a regular basis. I need to put the floor down today or tomorrow.


John Bridge
02-03-2003, 07:36 PM
Hi Scott,

MB (my friend, btw) is the only guy I know in the tile business who can walk across his fresh laid mud and not make footprints. Yet he wants you to wait a month before you tile it. :D

In the old days we floated the mortar and set tile on it almost in one operation. There were times when I floated, set and grouted small bathroom floors all in the same day. As far as I know, those floors are still there. :)

02-04-2003, 08:39 AM
I am looking at the threshold detail and wonder how the saddle will work. I have 1 1/4" mud bed that holds 1/2" pex radiant tubing + 3/16" tile + thinset . the other side of the door is going to be 3/4" hardwood.

How do I do the saddle so that you don't see the exposed edge of the mortar bed?

02-04-2003, 02:57 PM
This is how I make them. The hard way and the easy way.

The hard way: Get out your measuring tape and take measurements of the height from the hardwood to the tile and from the tile to the height of threshold on the tile. Using a piece of Oak the thickness equivalent to the combined elevations and your table saw, cut the bevels and then the knotch between the two floors. A cabinet shop or a hardwood supplier may be able to cut this for you out of stock threshold.

The easy way: Get two oak boards, each about an inch thick. One goes on the hardwood side and should be planed to the elevation of the tile. Scribe a line for this and cut it out with a table saw or bandsaw. Sand smooth. Lay the second piece on top, and bevel the sides. Mark where they join and look good, glue it up, and then stain and varnish and nail in place with some long finish nails, counterset and filled. Or screw them and plug the holes.

The hard way is tough because at least on the ancient homes I work on, the subfloor is never level or straight. It is hard to make a straight rabbet fit an unstraight floor; shims will make the threshold look terrible. The easy way is easy 'cause the elevation of the tile is scribed to fit. The top beveled piece therefore fits perfectly.

02-04-2003, 03:34 PM
Scooter I don't know if I follow you. Are talking only about the wood sill that will abut the mortar bed and marble saddle? Is the bevel the slope down to the hardwood elevation, and what do you mean by notching between the floors?

What about the tile side?

Should I lower the mud bed so that the 5/8 marble saddle is flush with the tile?

see my jpeg


John Bridge
02-05-2003, 07:09 AM
I don't think Scooter realized you have the marble saddle in place. He is talking about a wood piece that will overlap both the hardwood floor and the tile floor. No marble saddle.

02-05-2003, 10:03 AM
Nothing has been installed yet, I am just trying to figure out all of the details first.

02-05-2003, 10:48 AM
This Rabbetted Wood Threshold takes the place of a single elevation Marble Saddle. I actualy prefer the wooden thresholds for a couple of reasons: (1) I am a carpenter, and like wood; (2) It can be easily beveled so you are tripping over the darn thing; and (3) The materials are readily available and "softer" to the tootsies.

02-05-2003, 10:54 AM
Use a single bevel sill . The single bevel sills are pitched and will make a smoother transition

02-05-2003, 11:14 AM
A.N.S.I. A-108.1B-- Normal job site conditions 70 f. is adequate,but longer mortar bed cures up to 10 days are desirable. (for dry-set or latex mod.) --- bottom line next day

02-06-2003, 10:36 AM
another question:

should i install the mud bed to the inside of the wall plate or the outside of the wall plate at the door?

02-06-2003, 11:50 AM
If both finished floor elevations are identical at the transition door, then I would put the mud bed at the center, between the two rough jambs.

If the tile is higher, which is usually the case, you will have to make a threshold. In that event, I like to end the mud bed on the inside of the rough jamb.

John Bridge
02-06-2003, 06:07 PM
It also might hinge on which side of the jamb the door is hung on. If a narrow threshold/saddle is desired, the mud should end halfway under the closed door. :)