Redgard dry time [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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07-26-2011, 02:37 PM

I have been working on tearing out my shower/tub and getting ready to tile for the last week. I have read a lot of helpful advice on this forum, but overlooked the foundation cure time for Redgard on the Redgard spec sheet. I ran across a thread on this site saying the foundation has to cure for 28 days before redgarding. Do you go by this for the mortar slope? We filled in the hole where loose mortar had been under the tub around the drain area 5 days ago and put in the sloped base 3 days ago. I planned on painting the first coat of Redgard today on the base. Should I wait(28 days would be hard to do)?

Also, I bought Omnigrip and used it for the counter and floor with no problems yet. I'm not going to use Omnigrip in the shower after doing more research, but is it ok to use just for holding down the mesh tape and filling in 1/4" gaps in hardie board?

Thanks in advance,


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07-26-2011, 03:47 PM
If you are talking about a mud bed shower pan, you should be just fine putting the Redguard on; it is small, the moister will have escape routes, and it is mixed very dry. If you are talking about concrete its a whole different beast.

Use thinset for your CBU joints.

07-26-2011, 07:57 PM
Hi Rick. Omnigrip is mastic, it has no use in a shower.

07-27-2011, 09:02 AM
Yes I did mean the mud bed. We used quikrete mason mix type S to form the mud bed and to fill a hole around the drain that was nothing but loose mortar mix(pic attached).

I will use thinset for the joints.

Thanks for the help guys!

07-27-2011, 09:06 AM
...and the shower valve glued to the sheetrock is the old valve and is coming out. We may not be doing everything by code, but we didn't do that. HA

07-27-2011, 09:08 AM
Rick, Type S mortar is OK for the pre-slope, but you should mix up your own deck mud using Sand Topping Mix and play sand (2:1) for your setting bed. The setting bed needs to be able to drain water through it, and the mortar you used for the pre-slope won't do that very well. Besides, it will be easier to form the sloped shape using deck mud than "fat" mud.

07-27-2011, 09:32 AM
I was trying to go by the model on the Redgard spec sheet. Going by that I used the type S for the concrete slab slope. I was planning on using flexbond for thinset and not putting deck mud on top of the redgard. ....and I should mention the way you are talking about is also on the spec sheet. Is that the preferred way to go?

07-27-2011, 10:06 AM
Sorry, Rick, I missed the Redgard pan part. I'll give you my don't do it speech, then go on with your project: Don't do it. While Redgard is approved for such an application, I believe the risk of having a pinhole in the membrane or damage to the connection between the membrane and the drain fitting is too high, especially in light of better products. With any roll-on membrane, you are the only quality control your shower will have. If you must use one, get yourself a wet film thickness gage and check your work.

OK, that's off my chest. :D

The thin bed detail you are following presumes you have the appropriate cast iron drain fitting. This fitting has a shorter top section and a different weephole arrangement than your run-of-the-mill drain fittings designed for a 1-1/4" thick setting bed. If you don't have that fitting, change your plans and use the other detail.

07-27-2011, 10:13 AM
Thanks for reply! I didn't pay attention to the cast iron part of the diagram. Better go with the sand mix!



07-27-2011, 10:45 AM
looks good so far man, seems to be just like mine. Make sure you have enough slope since the drain is not in the center like a normal shower. Are you making a divot around the drain??

07-28-2011, 08:32 AM
No we didn't make a divot. Just ran the 1/4" sloped slab to the top of the bottom clamp drain, leading to the weep holes.

07-28-2011, 09:10 AM
im no pro but i think the divot is a very good idea!!

07-28-2011, 09:18 AM
Phil, if you are following the "thick setting bed" model like Rick, you don't need a divot.