Leveling a floating sub floor for 3/4 Maple hardwood

[nifaron]

I'm going to be installing 3/4 maple hardwood in an addition on our house. The addition is 2/3rds cement (2' above grade) and 1/3rd plywood sub floor.

My plan at the moment is to build a 2 ply floating sub floor using 3/8" plywood. My concern is that there are a few minor low spot and a few bumps in the cement that will cause the plywood to not lay perfectly flat. Do these need addressed? How would it be best to address them?

I've heard of people laying a very thin layer of fine, dry stand between the vapor barrier and the plywood that will shift to fill in the low spots. Is this crazy?

Advice, please. Thanks much!

Aaron

 

[Ernesto]

Yea very crazy, the sand thing is a handyman/DIY'er fix. Grind the high spots down and level the low spots wth exterior grade patch. Use MVP4 over the crete and six mil plastic.

Whats under the plywood?

 

[nifaron]

Yea very crazy, the sand thing is a handyman/DIY'er fix. Grind the high spots down and level the low spots wth exterior grade patch. Use MVP4 over the crete and six mil plastic.

Whats under the plywood?

What is the best way to grind down the high spots? I either own or have access to virtually any tool...

The part that's plywood is over the basement and thus nailed to the floor joists. When they added the addition in the early 80's they (like idiots) built it on a slab instead of a crawl space (or better yet a basement)... the slab has been a total headache from the pvc plumbing IN the cement to the lack of any HVAC ducts at that end of the addition... but I digress...

Thanks!
Aaron

 

[Ernesto]

Aaron, you remind me of my new friend Aaron Roth from upstate NY who moved here last year. Hmmm are you jacking me around again Aaron? If so I'm coming over there and......never mind lol Next thing you know you'll be posting over at TFP again for bad advise. heh heh

Anyways. I use a 7 inch grinder with a dust cover attached to a vac with a hepa filter. Then you can screed patch over the low spots in the slab with a 6 ft level.

You cannot get this Dewalt model at the box store, but a close one. This one has an extra horsepower or 2. I got it on Amazon.com.

 

[nifaron]

Aaron, you remind me of my new friend Aaron Roth from upstate NY who moved here last year. Hmmm are you jacking me around again Aaron? If so I'm coming over there and......

...and helping me with my floor, right?

You cannot get this Dewalt model at the box store, but a close one. This one has an extra horsepower or 2. I got it on Amazon.com.

What's the model number on that Dewalt? I always need an excuse to buy another tool! My favorite Dewalt spot online is toolking.com...

Thanks!
Aaron