Tile installation [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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07-01-2001, 12:32 AM
I'm drawn to this forum because I like John's straight forwardness. We need advice. We're buying a new home in Sacramento, CA. The home comes with carpet, but we want to upgrade to tile. I've watched the contractors build another home and was not impressed with their attention to detail. What do we need to watch to make sure that the tile is set properly if we finally choose tile? Also, if we choose to go with our own tile setter here in Sacramento, does anyone know a good tile setter in Northern CA. Thanks

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John Bridge
07-01-2001, 11:45 AM
Hi Raymond. Welcome aboard!

There are a bunch of folks here who will be happy to give you as much info as you want -- maybe even more than you want. One thing, though. We need to know what the subfloor will be made from, i.e., concrete slab, plywood over joists, trusses, etc.

07-02-2001, 01:43 PM
Thanks for such a quick response to my querie! Regarding the substrate for the tile floor that we are ordering, that floor will be installed on top of concrete. Got any advice and/or referrals for us here in Sacramento CA we'd appreciate it. Thanks

John Bridge
07-02-2001, 02:51 PM
Hi Raymond, I guess I'll lead off.

First of all, I don't know any tile setters in Sacramento. I have a sister who lives there, but she won't be any help. Dave Gobis, executive director of the Ceramic Tile Education Foundation, knows people all over the country. He posts on our "Hangout" board, but it might be quicker to email him.

dave@tile school.org

I really would like some input from some of the others here, but I'll say this right now. You need to let the concrete cure, so it might be a good idea to let the builder put in the cheapest floor covering available and then have someone install the tile later.

Cracks are a problem with slab/tile installations (especially here in Houston). Allowing the slab to age a while will allow cracks to occur if they are going to. Then they can be dealt with.

Let's hope we get some more opinions.

Bud Cline
07-02-2001, 03:53 PM

At this point the curing of the slab is critical since this is new construction. Technically the slab should be well cured by the time you are ready for tile. To protect yourself you may want to have an isolation system installed onto the slab to seperate/detach the tile from the slab. The first product that comes to mind is a product called DITRA. This will eliminate the possibility of slab cracks being transmitted into your tile job.

07-02-2001, 05:42 PM
Right again Bud.Concrete can deform or crack for a year or even more.If I'm not mistaken the industry calls for a minimum 28 days curing time before any flooring should be installed.

Even then I agree with Bud about the "uncoupling" membrane like Schluter-Ditra.It costs more money but could very well save you from a far more expensive repair job down the road.

Bud Cline
07-02-2001, 08:04 PM
"THEY" say concrete cures in 28 days, true enough. But in some cases curing and drying are two different things, depending on a lot of factors.

Hell twenty years ago I poured some boat ramps under water, I'm sure they have cured by now but I doubt they are dry yet.

Point is, a detachment of sorts will counter a whole lot of potential problems. For an additional $2+- bucks now a failure can be avoided.

07-02-2001, 08:40 PM
Hello John, Bud and Keith,
One thing for sure about you guys; sounds like there's about 212 years of experience between you all. So, installing tile on concrete means the concrete needs to be "cured", but cured or not, we would do well to order a detached membrane between the concrete and the tile. Right? Now, that makes sense to me and I really appreciate the helpful responses. But, after looking at Bud's last comment, could you help me with this understanding; what is the difference between curing and drying? Also, are there grades of Ditra and about how much does it add to the cost per square foot or yard?

Bud Cline
07-02-2001, 09:05 PM

There are reams of paper written on this subject but suffice it to say that the curing of concrete in 28 days is a scientific formulation fact on which most all related continueing construction activities are hinged.

Then there is flooring. Just because concrete is cured doesn't mean it is dry. On and in ground concrete has the ability to rehydrate itself back and forth depending on the availability of moisture adjacent/under the slab to supply this hydration.

In areas of the country where the water table (ground water) fluctuates up and down seasonally concrete can add and lose moisture seasonally also. This has no effect on the strength of the slab except that the more moisture you can keep on and around a slab during its initial cure, the stronger the cure. I don't really understand any of this but I have picked up a thing or two over the years.

Moisture in concrete slabs is an enemy of most adhesives and floor coverings. I do know that.


In the Houston area John uses a system of detachment that installs a cement floor on top of the slab to isolate the tile from the slab. He would be happy to explain this method and its cost I'm sure, it may be something that will work for you.

DITRA on the same hand, is the latest alternative to this mud detachment method. DITRA is a plastic product that attaches to the slab with thinset, it is constructed so as to allow movement in the slab while not allowing this movement to be transmitted to the tile. The tile is installed with thinset in normal fashion. I'm finding that DITRA is costing about $1.25 per square foot and installation is running about $1 per square foot around here. To my knowledge there is only one grade of DITRA (its design has recently been changed and improved) and it will add about 1/8" to your slab before the tile.

[Edited by Bud Cline on 07-02-2001 at 11:13 PM]

John Bridge
07-03-2001, 06:43 AM
Not to get too technical (I'm not able), but to expound on what Bud has already said, portland cement (the glue of concrete) cures by "hydration." The water actually does the work, not air. So concrete cured underwater is generally stronger than concrete cured out in the atmosphere. Under ideal conditions concrete reaches "95 percent peak strength" in 28 days. This is about as strong as it will ever become. It then begins the decades long process of deterioration.

I still bond tile to concrete slabs with thin set mortar. It's not the best thing that can be done, but in most situations the budget will not permit a membrane application over the entire floor. We don't have too many problems. I'd say 95 percent of our retrofits perform as expected.

When there is a problem, though, it's a mess.

Besides Ditra, which is without doubt the most expensive uncoupling system, there are scores of other anti-fracture membranes, some are fabric and some are painted onto the concrete. Do a search on any search engine and you'll come up with a handful. Most do not add any appreciable height to the floor.

I would not worry about a continuing moisture problem in Sacramento. They are draining all your water off to keep L.A. from drying up.

07-04-2001, 05:39 PM
If cost is not an issue, Ditra will allow you to tile immediately with confidence that any hairline cracks will not be transmitted to the tile. Another option is to live with a different floor covering for a year or so, then you will be able to see where the cracks, if any, develop and they can be individually treated with something like Laticrete's Blue 92, or Mapei's PRP M19. A years not a long time, but it beats 28 days and will get you through at least one "season" of weather and cure time.