Subfloor high spot on a laminate floor installation

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Old 05-04-15, 10:51 AM
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Subfloor high spot on a laminate floor installation

I'm helping my daughter and son-in-law install a floating laminate floor in their small kitchen. The laminate is 8mm thick with a foam underlay attached and has the usual tongue and groove locking edges.

I've read a lot of comments on this forum so I know this type of flooring is not favored but it fits their budget and taste.

The laminate planks are 15 1/2" wide and 46" long and the area the floor will go on is 6 1/2' at its widest point and about 12' long. The laminate pieces will be installed with the long side running parallel with the length of the room.

Here's the issue I'm concerned with:

I used both a 4 foot and 8 foot straight edge to check for any low and high spots in the existing 60 year old floor which is 8" or 10" glued down vinyl squares. The floor is sound with no cracks or raised corners or gaps but there is one high spot over an 8' length that is about 3/16" which I believe is about at the acceptable limit.

Since I'm 99.9% sure the existing floor tiles are asbestos glued to the wood plywood subfloor with black cutback adhesive, I don't want to mess with it.

What I'm thinking of doing is to lay the new floor out so the high spot falls as close to the center of the width (15 1/2") and length of a laminate piece as possible in hopes that it will minimize the risk of the pieces in that area from coming unlocked and creating a gap.

I'd appreciate your feedback on whether this approach might help or whether there are other techniques or things I could consider doing during installation that might help.

Thank you
 
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Old 05-04-15, 03:07 PM
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I wouldn't be afraid to remove the existing floor. Try to remove one of the tiles. See what happens.
 
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Old 05-04-15, 03:36 PM
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Try to remove one of the tiles. See what happens
I did try after my daughter and son in law moved in and decided to remove the carpet in the kitchen that was covering the original tile floor.

I used a utility knife and cut deeply around the perimeter of a tile under the refrigerator and that tile did not want to lift or move. I would have to chisel it out to separate it from the black adhesive which I elected not to do.

After determining the original tile floor was very sound, we decided it was probably best, particularly after concluding it was asbestos and cutback, to put the new laminate floor on top of it.
 
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Old 05-04-15, 05:04 PM
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I know what you mean. I've had experience with that black glue. Is there access from a cellar so you could cut out the sub floor with it?
 
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Old 05-05-15, 04:28 AM
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Is there access from a cellar so you could cut out the sub floor with it?
No there really isn't practical access.
 
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Old 05-05-15, 05:00 AM
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It still could be done. You would set the circle saw to the depth of the floor & sub floor & cut squares about 2'x2'. It would look like a tic tac toe game. Then you could pry the squares upwards. The hardest would be the first one or two. That would give you total control over the height & level of the floor.
 
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Old 05-05-15, 06:08 AM
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Pulpo, I really appreciate your comments and suggestions but I'm just a retired DIY'er trying to help the kids out and need to find a much simpler solution.

Ideally, I'm looking for some "tricks of the trade" that flooring people have used in similar situations where a less involved, but effective, approach has worked.

Actually, a first question is whether a 3/16" high area over 8' is really going to become a problem, or is it a conservative guideline that may really be ok?

Please keep the comments and ideas coming because I appreciate them.

Thank you
 
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Old 05-05-15, 06:42 AM
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Is the main problem where the kitchen floor meets the floor in the next room?
 
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Old 05-05-15, 07:14 AM
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Is the main problem where the kitchen floor meets the floor in the next room?
No, its essentially in the middle of the floor. Its about 5' or 6' in from the doorway along the length of the kitchen and pretty close to halfway in the width between the oven on one side and cabinets on the other side although the width at that point in the kitchen is only about 5 feet.
 
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Old 05-05-15, 07:58 AM
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Is the high spot between two rows of tile? If you could remove those two rows of tile, you could skim coat the remaining void thus eliminating the hump. Trying to balance your very wide laminate over the hump will cause the floor to bounce every time you walked over the area. Use a 3" stiff putty knife to slide under the tile. Gently hit it with a hammer until it releases. The issue with asbestos is the dust created, if any. Just take your time and carefully pop as many off as needed.
 
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Old 05-05-15, 09:33 AM
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Is the high spot between two rows of tile?
czizzi, I'll have to measure and mark up the existing floor a bit more to see exactly how much area the high spot covers. But I think the answer is that it is essentially between two rows because even though the existing tile is solidly adhered to the subfloor, you can see a slightly wider gap between the tiles in those two rows unlike the tighter almost non-existent gap in most of the rest of the floor.

Is the following the approach I'd take to remove the high spot?

1. remove as many tiles in the general area that is now high until the floor is flat over an 8' span when the straight edge is resting on undisturbed tiles surrounding the previously high area.

2. Using a leveling product such as one made by Henry build up the area where the tiles were removed to the point of it now being level or within an acceptable amount

Are there others steps that I need to follow?

Will the leveling product adhere adequately to the cutback residue after removing the appropriate tiles or does the cutback need to be removed as well and, if so, how?

Typically, how long do you need to wait for the leveling product to cure before laying the floor over it?
 
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Old 05-05-15, 02:36 PM
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Give me a link to your laminate for cross check on floor prep specs if you could. Most laminate is only 8" wide, yours is double so I want to double check.

Read the specs and limitations on the patching compound you are using. It will call out cutback adhesive as suitable to go over. I have had good success with Speed Finish from CBP found at the big orange store. Not a fan of the henry product as it takes longer to set up. Look in the tile department of big orange. http://www.custombuildingproducts.com/tds/tds-110.pdf
 
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Old 05-05-15, 03:03 PM
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Here is the link to the laminate flooring at Home Depot. Its the same brand and pattern but we purchased it at Grossman's Bargain outlet at a lower price. I'm giving you the Home Depot link because it has a much broader description than Grossman's. You can also go to the Faus Group's website, the parent company or manufacturer, for some information.

Innovations Tuscan Stone Sand 8 mm Thick x 15-1/2 in. Wide x 46-2/5 in. Length Click Lock Laminate Flooring (20.02 sq. ft. / case)-904067 - The Home Depot
 
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Old 05-05-15, 03:16 PM
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Neither sites give any information on subfloor requirements and flatness. If you can get one of the tiles up, the rest will be easier as you can simply slip the putty knife under the other ones. Should work in your situation to minimize the hump.

Let me know if you have any more questions about the installation. Make sure that the product has acclimated for at least 3 days inside near where it is to be installed. Leave an expansion gap all the way around and cover with molding. Stagger all joints, and if you have the tile pattern, must make sure that the patterns line up. That means that you may not be able to use the waste you cut off to start at the end. Those tile patterns usually result in more waste, so hope you have worked that into your estimates.
 
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Old 05-05-15, 03:29 PM
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Neither sites give any information on subfloor requirements and flatness
FYI...last week when I started thinking about installing this laminate and my concern about the high spot, I called the Faus Group's Technical Services dept and spoke with a guy who told me the following.

The floor doesn't need to be level, but needs to be flat within 1/8" over 4' and 3/16" over 8-10'. This was the basis for me starting this thread.
 
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Old 05-05-15, 04:15 PM
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If we are taking about fractions of an inch that are 1/4" or less, I don't think that they would cause an installation problem. I would think that any problems that might arise during the installation can be solved by adjustments with the underlayment.
 
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Old 05-05-15, 04:19 PM
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I would think that any problems that might arise during the installation can be solved by adjustments with the underlayment.
The underlayment is attached to the actual laminate planks and it is not advised to add addtional underlayment as it will cause too much movement at the click lock mechanism. Yes, a "hump" needs to be addressed.
 
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Old 05-05-15, 04:33 PM
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czizzi,

This may be a stupid question, but other than putting carpet over the existing floor, is there any other type of flooring we could consider putting over the original asbestos vinyl squares that will tolerate leaving the high spot as it is without future problems arising?
 
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Old 05-05-15, 04:48 PM
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Not sure why you ask the question, but any floating floor will work fine. Don't get underlayments confused, the last post referred to the foam backing on your laminate. Not your subfloor make up. Adding additional foam underlayment is not advised. With laminate and other click lock flooring, thicker padding is not always better. Your plan as previously outlined - remove two rows wide and skim coat will be fine.

If we wanted to get technical, I would have advised against laminate in a kitchen area as water spills will cause failure. But assumed it was a budget thing for your daughter to help get them started in their new home.
 
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Old 05-05-15, 05:00 PM
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Targa, it's not a stupid question. Rubberized flooring would work great.

Black Home Rubber Flooring - 4x10 ft x 1/4 inch, Home Rubber Gym Floor
 
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Old 05-06-15, 07:34 AM
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If I take the approach of removing the necessary existing tiles in area around the high spot, I believe I'll need to remove the cutback residue down to the plywood subfloor before applying a leveling product.

A internet search indicates for removing asbestos based cutback adhesive the wet scraping method needs to be followed. I'm not familiar with it and hope someone can describe how to do it and whether it will in fact work or if there are other methods that I can use.

Thank you
 
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Old 05-06-15, 09:22 AM
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The link I provided earlier says that speed finish is approved for use over cutback adhesive. Save yourself the headache and just skim it flat without scraping.
 
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Old 05-06-15, 10:24 AM
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czizzi,

OK. Sounds like the easiest approach. Thank you.
 
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