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The Daily Insight

Can you Redgard over Kerdi

Author

William Taylor

Published Mar 07, 2026

Can you Redgard over Kerdi? No, it won’t interfere with the performance or adversely effect it. RedGuard is not harder to adhere to. There is no reason to use both products although it can be easier to use the RedGuard in corners and niches without the build up you can get with kerdi.

Will unmodified thinset stick to RedGard?

Powdered, unmodified thinset mortar will stick to RedGard waterproofing membrane and securely fuse your tile in place. … DO NOT use a premixed thinset mortar—it will not stick to RedGard. Use a powdered thinset mortar you mix yourself.

Why can't you use modified thinset on Kerdi?

Modified thinset mortars aren’t recommended for use with Kerdi because they must dry out to gain strength, whereas the membrane inhibits drying, which can lead to unpredictable results. … Schluter’s recommendation is to use unmodified thinset mortar when installing Kerdi over most shower substrates.

Can you tile right over Kerdi board?

For most installations of KERDI-BOARD, tile can be installed right away. Exceptions include curved wall areas and non-bearing partition wall systems. In these applications, the tiles can be installed once the bonding materials have cured sufficiently to stabilize the KERDI-BOARD assembly.

What Thinset should I use with RedGard?

The Flexbond modified thinset, which is sold at HD, lists redgard as one of the surfaces it can be applied to and therefore, following manufacturer recommendations, a person should be using a modified thinset like Flexbond over Redgard.

Do you need to seal Kerdi-board?

KERDI-BOARD by Schluter is one of the best ways to waterproof a shower. … A lot of folks like using cement board but it’s heavy and requires a waterproofing membrane over it. Furthermore, if you’r working in an older home KERDI-BOARD fits better than cement board in odd spaces.

Do you need to use RedGard over cement board?

You really don’t need the RedGard, but the more protection the better…so go for it. And yes, you can do the boards beforehand. But, hit the filled seams & screws (your weak points) as soon as a panel is ready to give it some time to setup. You’ll have to wait for the fills to dry or at least setup anyway.

Can I use modified thinset over KERDI?

In general, modified thin-set mortar is not recommended to set ceramic and stone tile, including large format tiles, over the KERDI membrane. Modified thin-set mortars must dry for the polymers to coalesce and form a hard film in order to gain strength.

What Thinset do you use with KERDI?

Schluter SET™, ALL-SET™, FAST-SET™ or an unmodified thin-set mortar must be used to construct all KERDI seams to ensure watertightperformance of the system.

Is Schluter all set waterproof?

Schluter®-Systems offers a variety of systems for tile installation, including uncoupling and waterproofing membranes, shower systems, and building panels. … It is sag-resistant and ideal for setting tile on both horizontal and vertical surfaces.

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How long does Schluter all set take to cure?

I know, I said not to use modified thin-set to install tile over a membrane. Schluter has done a lot of testing in the lab and in the real world to develop a modified thin-set that cures completely in 12 hours when used to install tile over a membrane.

What is the difference between Schluter set and all set?

Schluter ALL-SET® is a specialized modified thin-set mortar specifically formulated for use with Schluter® membranes and boards. … Schluter SET® is a premium unmodified thin-set mortar specifically formulated to use with Schluter® membranes and boards.

How long after applying Redgard can you tile?

Allow the RedGard membrane to cure for 1 to 1 1/2 hours. The color will turn from pink to a solid red sheet with no pink spots when it is fully dry. It is most important that you wait for the color of the product to turn completely red as ambient conditions will make the dry time vary.

How long should Redgard dry before tiling?

The product is dry when it turns solid red with no pink showing, normally 1-1/2 to 2 hours. Depending on ambient conditions, drying time can take up to 12 hours. A water test can be conducted 72 hours after application if required. Clean tools and hands with water before material dries.

When can you tile over Redgard?

You need a full coating for the product to be effective. When you are finished you should let the walls completely dry for a day before tiling. Your tile can then be installed directly onto your walls over the membrane with a proper thinset mortar.

Does RedGard stick to Kerdi membrane?

Can you Redgard over Kerdi? No, it won’t interfere with the performance or adversely effect it. RedGuard is not harder to adhere to. There is no reason to use both products although it can be easier to use the RedGuard in corners and niches without the build up you can get with kerdi.

Do I seal cement board before tiling?

Contrary to popular thought, tile and grout are not waterproof, and some moisture will penetrate even if sealant is used. … However, if you choose to use concrete backerboard, which is much stronger and more durable than gypsum board, a water vapor membrane must be placed underneath it or a sealant applied on top of it.

How do you seal a Kerdi-board to a bathtub?

Apply KERDI-BAND waterproofing strips or 5″ (125 mm)-wide cut sections of KERDI waterproofing membrane. Solidly embed the membrane in the mortar and KERDI-FIX to ensure full coverage and remove air pockets. Apply KERDI-FIX or other suitable sealant to the lip of the tub and spread using a small notched trowel.

Is Kerdi-band waterproof?

Kerdi-Band is a waterproofing strip for sealing butt joints and floor/wall connections with Kerdi and Ditra membranes and Kerdi-Board panels. It is installed with unmodified thin-set to ensure a fully water-tight seal to prevent leaks. The 4 mil thickness of Kerdi-Band helps prevent build up under the tile.

Is Kerdi-board waterproof on both sides?

The surface of the board has gridlines consisting of 10 x 10 mm squares printed on one side. Material properties and areas of application Schlüter®-KERDI-BOARD is waterproof and can withstand all chemical stresses that typically occur in conjunction with ceramic tile coverings.

Is Schluter Kerdi worth it?

Great product. It takes a little longer than the traditional mud shower bed and water-proofing methods, but it is worth it. … My shower is water-tight, and the sloped floor drains water perfectly. The finished product looks great.

Can Kerdi be installed over plywood?

The Kerdi membrane system requires a 2” overlap at all seams; either with the membrane itself overlapping adjacent piece or with the use of Kerdi-Band tape. … Since thin-set mortar works over almost any substrate, the Kerdi system can be used over drywall, plywood, or the various cement boards mentioned above.

How does Kerdi drain work?

Schluter®-KERDI-DRAIN is a floor drain specifically designed to allow connections to Schluter-KERDI or other load bearing bonded waterproof membranes. The membrane is adhered to the large integrated bonding flange to form a waterproof connection at the top of the drain assembly.

Can you put 2 Kerdi shower pans together?

Yes. The KERDI-SHOWER- T/-TS/-TT trays can be cut to size to fit various applications. Ideally, the tray should be cut by equal amounts on all four sides to ensure a consistent height of the first course of wall tile. … The shower base can also be extended past the perimeter of the shower tray using dry pack mortar.

Is Kerdi shower pan sloped?

Schluter ®-KERDI-SHOWER-LT/-LTS are prefabricated sloped shower trays with integrated KERDI waterproofing.

Is Mapei premium mortar modified?

Polymer-modified, cement-based mortars such as MAPEI’s Large Tile & Stone Mortar are generally recommended for installing tile over radiant-heat systems. Refer to the written instructions of the radiant-heat manufacturer for recommendations of cement-based mortars.

Is Mapei Thinset modified?

MAPEI’s Ceramic Tile Mortar, Porcelain Tile Mortar, Large Tile & Stone Mortar and Large-Format Floor & Wall Tile Mortar contain polymer and are considered modified.

Can you paint over Schluter membrane?

Yes you can paint over Kerdi board but you will need to give it a light coat of joint compound and do a little sanding.

Can I use modified thinset with Schluter?

Schluter-Systems requires the use of Schluter SET™ , ALL-SET™ , FAST-SET™, or an unmodified thin-set mortar meeting the requirements of ANSI A118. … In general, we don’t recommend the use of modified thin-set mortar to set tile over the membranes because these mortars must air dry to cure properly.

Is thin-set waterproof?

Thinset is designed to adhere well in a thin layer that’s typically not greater than 3/16″ thick. … Although thin-set is not waterproof, it is isn’t water soluble. When moisture is present, it will not return to a liquefied state as mastic would.

Can Schluter Kerdi be used on floor?

With the KERDI-SHOWER-TT thin shower tray on a wood subfloor, you can build up the rest of the bathroom floor by installing either a 5/8″ or 3/4″ plywood/OSB panel on top of the wood subfloor along with DITRA or another Schluter®-Systems uncoupling membrane.