Float or glue engineered wood over very smooth concrete slab

9 years ago

Hello,

I am a recent first time homeowner who has been looking forward to finally be able to make changes/improvements to the house I'm living in. I don't have a ton of experience but I pay close attention to detail and thoroughly plan out these kind of projects

With that disclaimer out of the way, I'm hoping to get some advice regarding my options for installing a engineered hardwood floor over a concrete slab (house built in 70s). The wood is 1/2" thick 7" wide engineered Oak by Somerset. I was originally planning to glue down because thats how the pros do it and I wanted to do it right. I found Bostik Vapor Lock adhesive at a good price and was about to purchase. Then I pulled up some carpet to take a look at the slab and found that the slab is nice and flat but also very smooth. I did the water drop test and while the concrete did darken around the water drop, the drop itself remained beaded on the surface for a while. So, I don't think the slab is sealed, but the top layer is very nonporous.

At this point I took stock of my options: 1) mechanically abrade surface to get a csp 2-3; 2) chemically etch the surface; or 3) float instead of glue.

Option 1 kinda intimidates me. There is a tool rental business just down the street from me that has a couple concrete grinders but it just seems like the process may need a more experienced hand to get the finish right.

Option 2 seems a little more straightforward. I found some products by Surface Gel Tek that seem a bit more controlled and easy to apply than muriatic acid. Their HD24 Pregrind created a 100-80 grit surface which is about a csp 2-3. Their Tek Gel makes a 120 grit profile.

Option 3: My main concern with a floating install is the noise/feel of the floor. I have read that the higher quality underlayments can make the floor sound as if it were glued down. If I got this route, I think I'm going to go with the Floor Muffler Ultraseal.

Questions:

- What option would you go with?

- Are there different products that you would recommend?

- Would the acid etch be effective enough?

- I can't find many reviews about about the Surface Gel Tek products, any experiences?

- Can I replicate or come close to the sound/feel of a glued down floor with a floating floor with the right underlayment?

Thank you so much for any help you can give.

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Comments (5)

gregmills_gw
9 years ago
The most important thing im going to mention involves the concrete flatness/moisture

just by looking at the concrete is not good enough to deteremine flatness...take a 7ft straight edge and get on your hands and knees and check EVERY square foot. guarantee there will be higher and lower spots. spots that need to be addressed prior to any work regardless of glueing or floating the wood.

then while the water drop test is a good start. you will need to check the moisture level of the concrete. the last thing you want to do is spend all the work laying the floor only to find the floor buckled a few months down the road due too high moisture, then having the rip everything out and be stuck with wasted time and money.
slk230red
9 years ago
last modified: 9 years ago
If hueydj's concrete floor doesn't pass the moisture test for glue down installation, what should he do and/or what are his options?
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gregmills_gw
9 years ago
If the moisture test comes back high, you would need to figure out the cause of the high moisture. theres going to be an underlying problem, the task is to figure out what it is, and then based off that take the appropriate action.
PRO
Uptown Floors
9 years ago
I've never heard of using an acid solution for scarifying a concrete slab. Best to stick with familiar and or proven methods that installers use day in and day out.
User
9 years ago
I think you might be over-thinking this. My recommendation would be first, to get a sample of glue and wood and glue a piece down. Let it sit a day or two and pull it up. Did it adhere well? If so, you're probably good to go. If not, look at your options to abrade the surface.

Float or glue engineered wood over very smooth concrete slab

Comments (5)

gregmills_gw

slk230red

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