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Discussion Starter #1
I’m in the process of prepping the sub floor for floating about 800 sq ft of Kahrs. As our home is on a valley floor with clay for soil, I have a bit of movement from one end to the other, and more of a problem, in between. I would like to “flatten” the floor as much as possible, but wonder how much is acceptable. The Kahrs instructions only address drops in small areas, not long crowning humps or dips of about 1/2” to 3/4” in a 12’ run. I believe mechanically it will work, but I’m concerned about how it will look. The home is very open with a lot of glass letting a lot of light in and I worry about “waves” in the floor! The hardwood is natural Red Oak with a Matt finish.

Any ides as what will show and what I can get away with?

All the best…
 

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You are going to need to get this floor a little flatter than that.You are either going to have to sand the high spots and/or fill the lows.
You can get a straight edge that will bridge between the high joists and use either floor patch or some similar product and pull that patch or product along with the straight edge and smooth it out that way.
You could also use s.l.c. on this floor as well,you don't say if this is concrete or wood but either way you can pour this s.l.c. over the floor ,but it will be harder over the wood subfloor .
So let us know what type of subfloor this is and we can better direct you on which way to go :cool:
 

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I try to get the floor within 1/8". Narrow plank floors with close grains show imperfections more than wide plank, bold grain patterns.

There was just too much wrong with this floor and grinding it was out of the question. The lighting is east to west, it is an inch low at the camera end and had all kinds of whoop-de-doos. It was levelled as much as possible and we depended on the pattern to cover up the rest. If you knew, you could see it and once the furniture was in it all disappeared.
 

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Discussion Starter #4
Floorman: Sorry I didn't say...I intended to! It is a plywood subfloor over a crawl space. I am going to use a self leveling compound in another room. It is going to get carpet, but I will get some experience!

Teetorbilt: The Kahrs Gent is a WoodLoc system that is a 3-strip plank 7-7/8" x 95-3/8" with a "high shade variation" description. I like the "whoop-de-doos" term because that is certainly what my floor does!

Keeping in mind this will be a floating installation; do I need to be within 1/8" over the entire 800 sq ft? That would seem nearly impossible!

Thanks again... :D
 

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I, somehow, managed to expand the pic. This is looking east, where the sun rises. Note the sidelight, door and plantation shutters, lots of light can come through here. At the camera end are french doors with sidelights on both sides.....more light in the afternoon.
This is Pergo and I just caught a repeat that shouldn't have happened. It took the camera to point it out, I have walked that floor a hundred times and never noticed.
Can you get within 1/4"? I have some cheap tricks.
 

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Discussion Starter #6
Teetorbilt: I've taken more measurements and with lots of creative work, I MAY be able to get it within 1/4"...what do your "cheap tricks" involve?
 

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Discussion Starter #7
It's nice to be working on my own house with no hard deadline, but, for the sake of the household, I do need to get this done! Anyway, I think I've develpoed a plan to level the subfloor, but I am more "frame & finish" and never used Self Leveling Underlayment before.

Any tips?
 

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Sorry for not getting back. How are you checking the floor? String method?
You can use self leveling compounds for low spots as long as the floor is level there. You can use some creative masonry to 'soften' the drops. Cheap formica sheets can be used to shim when glued down with a good construction adhesive and you can layer underlay in small areas that will never be exposed to permenant loading (furniture).
When I get time, I will write a piece on this.
 

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Discussion Starter #9
Thanks for getting back to me.

I am taking spot readings, every foot or so, using a "Less Expensive" laser level that actually is working rather well. I've found I have some rather large "whoop-de-doos" and was going to use another layer of ply in the very low spots, then use the SLC to level to the higher areas.

I don't quite understand the use of formica only in unloaded areas. I thought the formica would be as good (or better) than ply underlayment.
 

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Scrap the cheap laser, looks good in the ads, ain't worth a damn in the real world. I'm developing one for floors, many problems.
For now, stick with the string line. I'm still doing it and using it to check the laser readings.
Sorry if I mislead you. I use mica in places that may be loaded to keep the floor uniform. I just happen to have lots of leftover mica from plugs and molds.
You can double up on underlay in traffic and narrow areas but never do this where furniture may be placed.
In my earlier days, I built a bookshelf/entertainment center over a floating floor. When loaded with books, etc., that side ceased to float. Just a word from the wise.
 

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Discussion Starter #11
Teetorbilt said:
You can double up on underlay in traffic and narrow areas but never do this where furniture may be placed.
Can you explain why? Most of the old section of my house is 5/8" ply subfloor with 1/2" ply screwed over it (lots of screws). Does this mean I shouldn't have any furniture in this section of the house?

I understand about "anchoring" the floating floor with the bookcase, and always wondered about that. So, what do you do instead? Live with nothing heavy, or no furniture at all (see above)? My wife would miss her piano!!!

All the best....
 

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By underlay, I did not mean subflooring. If you use underlay (the foam stuff that goes under the floating floor) to shim low spots, you should not place heavy objects on top of it because it will compress.
You need to find an economical, flexable material to fill in the low spots. I seldom work on wood subflooring and what I have done has been flat. If it were my job, I would launch straight into epoxies and charge it out. Perhaps Flor and some of the others have other suggestions.
 

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There are many things you can do to make the flor flat.

I really would not double up the underlay foam in areas IMO. Leveling the floor with a self leveler or using the trowel is going to be the best.
Or install new plywood or whatever.
Just make sure the filler material is a stable filler.
 

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Discussion Starter #15
Thanks to both of you...

That makes far more sense, and that is what I am attempting to do with a combination of plywood and leveling compound...what a job though!

All the best... :Thumbs:
 
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