Self Leveling Cements & SLC Tools [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile

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flatfloor
03-28-2002, 03:45 PM
SLCs – self leveling cements - Cement-based, polymer-modified, self-leveling products that can be applied in thicknesses from 1/8 inch (3.2 mm) to 1” (2.54cm) and that can be feathered at edges to match adjacent floor elevations. Pours deeper than 1” can be done by adding an aggregate, 3/8” pea gravel. SLCs can usually be applied over old or new concrete, ceramic tiles, wood, radiant heat and terrazzo. They cannot be installed over gypsum products.

Suitable as an underlayment for most flooring products, they cannot be used as a wear surface unless expressly stated otherwise by the manufacturer.

When the cement is added to water and mixed with an electric drill and paddle it will have the consistency of a pancake batter. The mixture is poured onto the work surface and spread into place. A minimal amount of “troweling” is required, usually one pass with a smoother (a toothless trowel).

Most of these products can be walked on within 2-4 hours of application and new flooring installed in 24 hours. Check with the manufacturer for detailed information.

SLC priming
When priming a concrete floor one coat is usually enough unless you see the concrete quickly absorbs the application.

Plywood and CBUs will require two coats wait for the first coat to get tacky before applying the second.

The primer can be applied with a soft bristle push broom or paint brush in small areas some pros also use a short nap roller. Rinse well with water for clean up. Don’t leave any puddles, they take forever to dry. A fan can be used to accelerate drying.

SLC over plywood
All pours over plywood require a mesh or lath. Prime the floor first then attach 2.5-diamond lath mesh. Fasten every 6” with staples. Or more as necessary.
[Edited by flatfloor on 03-29-2002 at 06:38 PM]

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flatfloor
07-25-2002, 04:21 PM
First and most importantly read and follow the directions for prepping the substrate prior to priming. This is the most important part of the job. All Mfrs. of SLCs require the same procedures. Oil, grease, sealers, adhesives, etc must be removed. Then BROOM the primer into the substrate with a soft bristle push broom. Eliminate puddles. If you do not follow these procedures the job WILL fail.

Aroumd the full perimeter of the floor (and this applies to large or small jobs) attach some self sticking insulating foam. It comes in rolls, the 1/4" thick material will do. The width depends on how high your pour will be. You can trim off the excess with a sheetrock knife after the SLC hardens. This permits expansion of the SLC and will prevent tenting of your tile.

Lets take a 2,000 SF @ ¼” it’s really not that big a deal. Four men can handle it easily. On smaller jobs, say a bathroom, have at least one helper. Lets assume it’s already primed and ready to pour. I’m going to figure 75 bags if yield per bag is 27 SF @ ¼”. To do this you will need:

2 mixing barrels
2 drills (1 for backup)
1 long extension cord
1 water-measuring pail
1 5 gal water pail to periodically rinse off the mixing paddle
1 small dolly
1 garden hose
1 smoothing paddle
1 30-40 gal. clean plastic garbage pail
1 plastic drop cloth (for mixing area)

Fill the garbage pail with water; keep the hose charged in order to refill the garbage (reservoir) pail as you use water.

Open about 70 bags of material with a utility knife.

Start mixing, mix two bags at a time, mixing requires two of your men, when the first batch is mixed place it on the dolly and one man transports it to the pour area where he and the spreader pour it. While that batch is being transported and spread, another batch is being mixed in the 2nd mixing barrel. Repeat until complete.

Allowing 3 minutes per 2 bag batch that’s not quite 2 hours.

You must size up the job in advance. Make sure you have enough hose and extension cord. Defend against other trades using your water and power sources Keep a small pail handy with a few handfuls of dry SLC in it in case you see a leak. Throw a handful into the leak it will plug right up. If you are working in hot weather try to get some BLOCK ice for the reservoir (your favorite beer distributor) or lots of bagged ice if no block is available.

I have seen a lot of concern about melding the old material with the new, perhaps the stuff your using sets up too quickly, you should have at LEAST 10 minutes before it does.

I know, I know, I didn’t allow any time to assemble all the material in place or to install stops (dams) or for standing around.

flatfloor
09-04-2002, 04:33 PM
I'm going to suggest a source for smoother and mixing paddles Bon Tool- http://www.bontool.com they ship UPS or may have a dealer nearby, reasonably priced. Tools are listed as epoxy equipment

Mixer (egg beater type) part no.....12-851-B7.... This may be cheaper at a big box.

Smoothing paddle 18"...14-916

Adjustable spreader 24"...12-689-B10 (small jobs not critical)

Smoother and spreader come with 5' broom handle.

Custom Levelquik ES Home depot will get this for you. You must tell them it is a SPECIAL ORDER MODEL # LQESL50. I



[Edited by flatfloor on 09-08-2002 at 05:35 PM]