Flooring and Carpeting/subfloor prep


QUESTION: Hello Chris I have 2 questions.

1.  I finished removing all floor patch in preparation to seal the concrete with an epoxy moisture barrier (due to possible slab moisture).  How much preparation is needed (cleaning) of the concrete is needed prior to applying the epoxy?  There is a white residue left from under the floor patch.  Does all this need come off?   Also there are some areas with small amounts of floor patch.

2.  The installers installed the floor the same day they installed the floor patch (they used fans to dry the patch).  One year later the floor buckled and the floor patch broke apart in places due to moisture.  How can I tell if the floor patch was not dry before they installed the plastic sheets and the floor?  Moisture reading of the floor is ok and I'm installing the epoxy just to be safe.

ANSWER: Minor white residue ..a dusting or spottiness or whisper thin remnants should be OK as long as it is not lifting or going anywhere.

If you want to remove 99.9% use a floor machine and sanding disk from the rental dept at Home Depot

Otherwise for further peace of mind call the manufacture of the epoxy and speak with technical services. They will inform you as well.

White floor patch indicates a gypsum based patch. Today and since the 90's industry standard is a GRAY / GREY portland cement base rapid drying patch with polymers added for bonding strength.

It is against the FCI (floor covering institute) regulations and standards to use white gypsum base patch ...it should be outlawed from the shelf. It promotes mold and mildew growth and has no PSI strength to speak of. As in your case any moisture transpiring from the slab just made the product worse.

There is no way to see the past conditions from my desk...nor to determine if you had previous moisture issues without a test being done.

We always install the same day after the patch is dry and use fans to speed the drying
process. The bag will state "dry within 20 minutes or as much as 2 hrs depending on thickness".

How are you testing / measuring the moisture now????


---------- FOLLOW-UP ----------

QUESTION: I tested the floor with a calcium chloride test kit but the tests was acceptable (no moisture.)  But we had heavy rains last winter which I believe caused the moisture problem so I want to add the moisture barrier to be safe.

The patches are white.  When I rub my finger across it a white powder is transferred to me finger.  Directions say to remove white residue (salt deposits?) with muriatic acid.  (The floor patch that was installed was gray in color.)

I have seen people epoxy coat their garages and every case the paint lifted.  So I want to make sure I clean the surface well.  But since this is indoors (living room) I am concerned about using a bunch of water to clean and flush.

Thank you again for all you help.


ANSWER: Dirk, You can dilute the acid with water to use safely about 50/50.

As for rinsing a damp mopping will suffice. Maybe 2-3x  Speed the drying process with a fan afterwards.

Maybe you could tell me the brand of the epoxy barrier you are applying...
I have used DRI TAC successfully and recommend it for wood floors.



---------- FOLLOW-UP ----------

QUESTION: I am going to use the dritac 7000 however it is sold under a different name in my area (Garrison moisture gaurd). The tech specialist at dri tac tells me to put the floor patch first then the dritac.  This sounda odd to me (there is nothing to protect the floor patch from getting wet.

I am a stickler for following the manufactures directions.
Prepping the concrete slab first allows the patch to bond to the floor.
Use a quality floor patch product from Mapei (Planipatch)or Bostick (webcrete 95) Or Ardex (feather finish)

Use a liquid latex additive instead of water to further enhance the bonding of the patch. Except for the feather finish product just use water unless it recommends a latex additive.

There are many latex additives on the market. some quarts ...some gallons and 5 gallons as well.

For a small job you can use a gallon ...larger 5 gallons. Even a 50/50 dilution with water will increase bond strength.

I use whatever is most economical for my situation ...mostly this ceramic tile additive by CUSTOM Building Products...they are all the same in my opinion.



Do read this PDF article from Dri Tac for your information...

I doubt that the floor patch would stick to the epoxy once dry. It is like a hard plastic shell. Troweled on properly with no voids it should be about 1/8" thick roughly.

All the membranes out there require that you prep first then apply the membrane.


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20+ years flooring installation ...carpet,wood,tile and vinyl. Residential and commercial. I do not sell the products , just install what ever the shop / customer has purchased. I actually love seeing the finished project completed and it gives me great satisfaction to help others acheive that goal. If I don't know the answer I will say so, and then I will recommend another expert for you. I may even research the subject and answer to the best of my ability ...including links to my sources. I wish you all success Chris


20 years as an independant contractor

H.S. diploma A.S. agriculture Mt San Antonio JR. College

Past/Present Clients
Gene Bonas and Kevin Churnock Inc. Sheward&Son&Sons Century 21 Forte Const. Famous Footwear BOSE Corporation Homebodies General Contractor Perry Floors, Tri Cord Flooring T.J.'S Supplies

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