Anyone ever Moisture seal (MVP,WFM, etc.) over Ardex feather finish or SLC? I'm sure many do, and I have many times, but after I talked to one of Ardex's tech guys, I'm not so sure about it.
They will not back up any failures due to moisture being trapped between the slab and the membrane. He said any vapor beneath the membrane will cause the Ardex to fail. Is this something that can be thought of as , "I've always done it, and I haven't had any problems yet". - The hack way of thought.

That's an excellent Question. I am about to apply Ardex feather finish atop a partially self-leveled floor which I will probably add Taylor MS+ as a moisture barrier. I would be curious to know the answer too.

Depends on where the slc or ardex ppl say to put the product. Now lets say Bostik says to put their patch under the mvp, well thats what I would do cus it's basiclly the same dern stuff. If they say on top I wonder how it's going to bond. Never tried that.

I have always put it on the slab with no problems with either ardex of slc's. If that were the case being that the mvp is essentially the bostik adhesive without the anti-slump ingredient in it then all patches and slc's should have failed just under the adhesives.

I guess if the moisture barrier is of the same manufacturer as the slc and/or the feather finish, then you should be ok. Does the Ardex feather finish product limit you to an Ardex moisture barrier?

About a year or so before Bostik came out with MVP , Bostik was saying to spread Best as a moisture barrier. Use the back side of the trowel, and skim the concrete, let it dry overnight. I did a few of those back then, and never heard any problems. I tell you what, talk about a floor sticking! It was amaizing. Since they came out with MVP, that's what I use. But it makes me wonder if they came out with MVP just as big marketing money maker, well duh, ofcoarse they did, for obvious reasons, plus it costs more, and you use twice as much .

Interesting flooro, I believe'd and still do that two applications of adhesive helps stop more mve and most of all the skinned over fully set initial layer. Now that everyone is developing the two layer at once application I wonder if it is going to help as much as two layers set-up seperately. And when Bostik is going to jump in on this bandwagon???

PatentPending, utilizing adhesive manufactures other products on your installation is going to help in that if there ever is complications of the install you do not have two or three manufactures doing the blame game on you. Therefore and especially if a manufacture of the flooring makes their own adhesives and patching compounds or specify;s any to use that product it is wise to do so even though it may cost more.

However, this is not always an option unless you can order it with your flooring because many distributors do not carry a full line of one manufacture's products. Which really annoy's the hell out of me. It has been documented where some manufacture's products do not work well with others

Ya, what's up with this "two layer at once application" ?. Haven't used it yet, is it a different color, or what ? I would have to be convinced that a cured flat layer isn't more effective than a one shot trowell notch.

Besides, I kinda like getting paid extra to "Install a moisture vapor barrier"

I have yet to do one either as ppl are balking at the cost of glue down jobs and go with a floating application. I wonder if you could even work on top of one without the wood moving or glue squishing out of the seams. I envison a messy job, more time for it to set peroperly.

Stephen, you lost me above. What is it that you say will cause a "messy job"?

A double layer of adhesive applied all at once.

Oh, I see what you mean now. In the case of the glue that I will be using for my project (Taylor MS+), it can be used as a moisture inhibitor and sound reducer. However, it does not suggest a two-in-one application. Instead, it instructs you to use a special sawtooth trowel to apply the adhesive over the entire surface, wait 4 hours min. for that layer to dry, and then you apply the second coat of the same glue in order to gluedown the hardwood.

Yes but read further, see moisture inhibitor section or what ever it is. Taylor had adopted the new trowel like Stauf smp-960 does. They started it. They recently changed that lewast since last time I used Taylor's, I did the two step method.

See the glide on trowel at the bottom?

NOTE:
Due to spacer wear, replace Glide-On™ trowel
for every 210 square feet of MS Plus applied.

You are absolutely right. I was reading an older Taylor off the internet. There is a new trowel that must be used. But, as you said, this is still a two-step method of applying 1.) the glue with the special trowel, waiting for it to dry, and then 2.) apply the same glue with another conventional trowel as a floor adhesive.

The problem with their two step method is that their first coat does not slump flat like the Bostik MVP does. So you end up filling those ridges and it takes prolly 25% more adhesive to get 100% coverage as that MS-Plus does not slump one little bit.