Laminate flooring install over concrete - how clean?

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Topic by Becky posted 11-17-2016 01:47 PM 65232 views 1 time favorited 13 replies Add to Favorites Watch
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81 posts in 3207 days

11-17-2016 01:47 PM

There seem to be differing opinions on how Clean a concrete slab needs to be for a floating laminate floor install. I’m thinking what will cause more of an issue is how level it is, almost looks to have a hump in the middle and feathers out. Running a 4 ft level from almost the wall to almost the middle showed level. The space is only about 11×12 if that. Advice? I’ll try grabbing some pics tomorrow :)

-- aspiring jill of all trades

View Greg 's profile


32 posts in 1995 days

06-23-2014 02:44 AM

Level isn’t as important as straight. It can be out of level it just can’t have drastic humps in it. Just imagine the floor floats. If there are voids the floor will bounce. Make sure it’s pretty close to flat and get a good underlayment to take up any voids that might be present.

-- Ferdinand and Son Construction. Do it right the first time. Like us on Facebook

View EdwardThirlwall's profile


8 posts in 2156 days

07-03-2014 03:06 AM

The layers should be rugged but almost flat. When we had some renovations at the storage facility place, we immediately had some some floorings renovated and our contractor did an amazing job. I’ve observed that the floor is indeed rugged but not too flat to get the cement to cling well. Try it first within a small area to test.

-- Edward Thirlwall: http://supercheapselfstorage.com.au/facilities/sydney/

View aaronhenry's profile


1 post in 1784 days

07-05-2014 05:37 AM

I get your point, Edward. If the layer would not be flat the cement will get into it and stuck very hard. Laminate flooring needs more time. You can also contact commercial carpet denver who works well in all kinds of flooring.

-- http://carpetinmotion.com

View MoshupTrail's profile


39 posts in 2526 days

07-13-2014 08:41 PM

With an 11×12 area and installing a floating floor, you do need to get it flat. No peaks or valleys. The degree to which the laminate will tend to bridge valleys and become bouncy is probably also dependent on the size of the pieces. If your pieces are all 5” x 72” (quite large) you will easily get bouncy spots if the floor is not level. If you have smaller pieces, 2-3” x 24-36” I would expect it to be less bouncy, but would not take the chance. Lowe’s sells a nice thick blue underlayment, which is very good for taking up small imperfections in the surface and will also add some insulation. Insulation will be good to keep the floor from feeling dead cold like concrete. But in any case, you need to get the area pretty flat. (less than 1/8” variance).

-- Measure twice, cut once.

View Becky's profile


81 posts in 3207 days

07-30-2014 05:15 PM

ok – I think we’re ok on the flat part…so another question…. the more I look at the concrete, the more I’m willing to believe this was an exterior patio slab at some point that was enclosedinto a patio. I have some damp spots at two of the corners but nothing that is causing me huge concern…. but enough concern about moisture I’m debating on seeing if there’s anything like ditra for underlayment…minimal yet if there is a water issue hopefully it will not make it up into the laminate. I can’t have the height of anything else and was really really wanting to avoid having to scarify the concrete surface for prep but if I have to, I have to. I’ll try to remember to take and post pics when I get home from work – thoughts anyone?

-- aspiring jill of all trades

View Becky's profile


81 posts in 3207 days

07-31-2014 11:12 AM

Ignore the dog hair and the model please :) This is the adhesive that is remaining on the concrete surface even after a good vacuuming and all…the good thing is it doesn’t appear to be the asbestos containing kind. The corners have me a bit worried but I think they’d be ok with a layer of 4 or 6mm plastic vapor barrier.

-- aspiring jill of all trades

View greatfloorsanding's profile


2 posts in 1688 days

10-09-2014 08:30 AM

You should better clean the entire floor and make sure it’s dry before you place the laminate flooring. Otherwise, mold and other nasty things might appear after time. Btw, leveling is also very important!

-- Great Floor Sanding, London - http://greatfloorsanding.co.uk

View dbray45's profile


157 posts in 1863 days

10-09-2014 11:12 AM

Becky – if you are getting any moisture on the inside of a wall, you must get that resolved first. Trying to cover it up or mask it will come back to haunt you 10 fold.

If the ground outside is collecting water or holding it against the structure, that has to be fixed first. If you don’t have gutters, and the water is coming off the roof and standing, you may want to consider putting them up. You will still have to pitch the soil away from the structure. If it is on the interior, pulling the molding and seeing what you have is in order (you want to do this to put the floor in anyway). Whatever the case, the water is coming in and with it mold, mildew, and critters – it is compromised. Holes do not get smaller on their own – they get bigger.

Filling a crack in the floor of what was an exterior and now interior wall doesn’t make the water go away, it is still there. You have to find out where it is coming from, stop that, let it dry – then fill the crack.

Not fun but it is the only way to keep it dry.

-- Love woodworking and fixing most anything

View Becky's profile


81 posts in 3207 days

10-10-2014 01:09 PM

Thanks DB. I found out when they constructed the walls, they built the footers on top of the exterior carpeting. :( there was also a big hole to the exterior that I was able to fill, and I need to track outside and caulk or figure out where it’s at.We just had our gutters redone last year so that should have taken care of the other three corners. None of the drywall or floor is still wet, and I’ve cleaned up the bit of black mold I found and it’s not come back. We’ve gotten a lot of rain this week so I’ve been checking to see what those corners are doing.

-- aspiring jill of all trades

View Becky's profile


81 posts in 3207 days

10-10-2014 01:12 PM

Thanks GF! I got some SLC down now. I still have one bag of it I believe I’m going to have to use to level out an area where I ended up with a somewhat high spot where the other SLC didn’t get raked more towards the wall so it made a bit of a high area. it’s not horrible though -at least not as bad as I started with :D

-- aspiring jill of all trades

View ChristopherJames's profile


11 posts in 61 days

04-29-2019 06:15 AM

I reckon that you would need it to be relatively flat if you don’t want your tiles to be popping up all over the place. But I don’t think you need to have it screed. It’s an easy fix if you’ve got some concrete in self storage to just pave the whole floor over though in my humble opinion!

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43 posts in 7 days

05-17-2019 07:55 AM

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2 posts in 4 days

05-20-2019 07:02 PM

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