Monday, September 15, 2014

Can you use Liquid Waterproofing over Mapei's Mapecem Premix the next day?

I see Mapei has a new member on the John Bridge Tile forum.  This is a first I think for Mapei and so far this tech support person has made only seven posts.  I browsed through these post and found this one an moment ago.  Before you read the post from Mapei's man Michael have a look at the original question.

AquaDefense by Mapei

Next Day Liquid over Mud

Any afm wpm that allows next day application over drypack?? . . .

I've been told Ardex has such an animal but in researching I couldn't find
any evidence of that . . .

8 + 9 ?? Anyone . . . Curious if any of the fine folks here use a product as described above.

Much Thanks

Steve * 

Ardex 8+9 Photo

Hello Pooky,

I'm assuming you're addressing a shower pan situation in this thread. As far as your wanting to water-proof (wpm) over a dry pack the next day, MAPEI has a product called MAPECEM PREMIX that would address this concern. Using this fast-setting screed mortar as your dry pak will allow you to apply a waterproof membrane (wpm) such as our AQUA DEFENSE within as little as 4 hours. The Mapecem Premix sets up completely in 24 hours.

Hope this helps!


Mapecem Premix Photo

I have been using Mapei's Mapecem Pre-Mix Fast Setting Screed Mortar for years now (pictured below on my last build).  I must have read the label and instructions a few dozen times.  To my understanding Mapecem Pre-Mix sets up and can be covered with a sheet membrane in 14 hours.  Not 4.  It has no mention of liquid waterproofing in it's instructions to my knowledge and I have used it as quick as three days with no side effects.

Mapecem Premix over thin-set slurry coat

What I have found with Mapei's Aqua Defense and Laticrete's Hydro Ban is they can suffer from water blisters during extended flood tests. It was on an Aquadefence job over Mapecem Pre-Mix where I witnessed the third and final water blister.  It was a couple summers back and I quit using liquids that summer.  Never again for a shower floor.

Just to be safe I'll double check my facts today with Mapei.  Try and get something in writing from them.  Last time I emailed a question to their technical team I was called back. I would have preferred an email and today I'll ask for this is writing.  Lets see if Mapei will sign off on Michael's 4 hours recommendation.  I highly doubt it.  I've done a load of shower's like I have said with Mapecem Pre-mix and even on day two sometimes I see moisture still in the product.

Here you will find the full instruction sheet and safety data info of Mapecem  Premix -

The description for the product is listed as this:

Fast-Setting, Pre-Blended Mortar Mix 
Mapecem Premix is a fast-setting, premixed cement-based mortar for concrete repairs and subfloor preparation work. Mixed exclusively with water, Mapecem Premix provides an easy-to-use, high-compressive-strength, fast-setting mortar that sets completely within 24 hours without shrinkage cracks. When properly used, even in harsh conditions, its moisture emission is less than 3 lbs./1,000 sq. ft. (1,36 kg/92,9 m 2 ) per 24 hours as measured with the calcium chloride test kit. This allows the floor covering (vinyl, wood, rubber, linoleum, carpet, etc.) to be installed after 24 hours. Ceramic tile and natural-stone flooring can be installed after only 3 to 4 hours.

This product includes High-Hydrated Cement Technology (HCT™).

To view the full description follow this link:

After reading the info above the time before topping with a rubber topping is 16-18 hours.  The time before adding a cement based product is 4 hours.  No where in this link does it say Aquadefence can be added in 4 hours.  I'll send my email off to Mapei Technical and double check this.  You would think the person representing Mapei Technical Online would have the most up to date information.

Time and time again I find silly posts like this online.  Miss information or parts of a puzzle.  You need to be so careful with the advice you follow.  Even if that advice comes from a sales rep or store employee.  Most of the people selling these products do not use them everyday.  

I could be wrong but I highly doubt it.  I suspect within 3-4 days of this blog post of mine, the Mapei technical rep is going to do an edit of his post or a take back.  Lets see.

As far as a product endorsement for this Mapecem Premix - I love it.  I have tried many other products and even after having a falling out with my local rep over a missing linear drain I could not find a replacement product for this SKU. I tried, but still to this day I know of no better screed mortar than mapecem premix for my pre-slopes.

Photo Examples of AquaDefense over Mapecem Premix






In none of these photo examples above did I ever apply Aquadefense over Mapecem premix in four hours.  Not in 12 hours.  Not in 24-48 hours.  I have always left the jobs one week and the quickest I have tried was two projects where I waited three days or 72 hours.

** Source