Hey guys, here is what I'm dealing with:

5 yr old condo, 400 sq. ft living room, 1/2" thick Maxxon Gypcrete over 3/4 plywood, Float-Installing BR-111 5/16" Timborana engineered wood

Here's where I'm at so far:
1. removed all carpeting, padding, tackstrips and staples.
2. cleaned gypcrete surface of oversprayed paint and general dirt by scraping & sanding, which chewed up tons of sandpaper and blades. vacuumed as I went along.
3. vacuumed all remaining dust and debris.
4. double primed the Gypcrete with Ardex P-51. Mixed 1st coat 3:1, 2nd coat 1:1. Almost $40 per gallon!!!

The Gypcrete surface is now primed and ready to be repaired. There are only a few cracks around the edges of the room, and a few slight waves in the middle of the flooring. The floor will likely need to be flattened and the cracks repaired if I want to have the best job that I can do myself.

I've been researching this topic for a few days now, and I am getting nothing but conflicting information, all from seemingly valid sources. I didn't seek the advice of salesmen at local stores, but instead I went to the sources and manufacturers.

Some say I can use a Portland-based product to repair it, some say I cannot and that it will eventually cause a catastrophic failure of the Gypcrete.

I first contacted Maxxon for recommendations. I spoke to the head tech support rep for the Eastern region (I am in NJ). They do not make a product, but he recommends Ardex Feather Finish, which is Portland-based. "I've been in this business for 14 years and all my guys use it to repair Gypcrete. I've never heard that you can't use Portland-based product on Gypcrete.

I heard basically the same story from similar high-ranking tech-support people and eastern regional sales reps from Bostik and Mapei. All of whom are in the business for more than 12 years. They all said FeatherFinish, or a similar product will work.

The Ardex tech support people - 2 or 3 different ones - each said that I canNOT use a Portland-based product over Gypcrete. They recommended the Ardex GS-4. However, I only need to flatten the floor about 1/8", when GS-4 is supposed to be no less than 1/4".

So, what do I make of all this? I'd like to hear the thoughts of those of you who have considerable experience working with Gypcrete floors.

Thank you for your time.

The installations instructions say that the featherFinish can be used over all types of interior concretes or masonry. I saw no mention of Gypcrete. It says you can add an embossing filler, did you ask about that? Sounds like that is what you are trying to do.

You are trying to flatten and the GS-4 is a self leveler not to be thinner than a 1/4". I don't know myownself . I don't have to deal with any gypcrete where I live (yet).

You can use GS-4 and screed it, instead of pouring it out and letting it find it's level.

Portland on gypcrete, is a failure waiting to happen. Too much alkaline in gypcrete.