Skim coat of Thinset for floating floor leveling

[Gary_S]

I am doing a floating luxury Vinyl plank job in my home.When searching for Thinset as a floor leveler a lot Of places says it’s ok if less than 3/8” or so. After watching a YouTube video Last weekend I used Maipei Ultraflex 1 as a skim coat leveler for 8-10 small areas (1/4” - 3/8”) on my concrete floor that had carpeting previously. I guess I was trying to save some money vs Henry 549. I found out how gritty and sandy Thinset was Vs. Henry 549. I need to grind down some edges of the Thinset this weekend as it does not feather as well. Does anyone think these patches will pose any problem under a floating floor? Or should the patches be ground back down to the cement? (Have a cup grinder) It may just be me being paranoid but the area is 300-350 sq ft and as always patches are in the middle of room. I completed another small room but had used Henry 549 to level small areas and will spend the extra money going forward. Just glad I only did some small areas and that it s easier to correct.

 

[havasu]

You can shortcut your job with a cheaper thinset, but by the time you sand and work it to level, you are wasting lots of time and unless mixed properly, could crumble on you. The correct way to achieve a level floor is to use self leveling compound.

 

[Gary_S]

That’s the blessing of a floating floor I guess I’m ok/safewith what I have so far. Even if you have some crumble I assume you probably will not even know it

 

[JPfloor]

Even if you have some crumble I assume you probably will not even know it

Well maybe you won’t notice it. Depends how much crumbling. Too much and you will hear it, feel it, and possibly compromise the joints in the floor.

 

[Gary_S]

Well maybe you won’t notice it. Depends how much crumbling. Too much and you will hear it, feel it, and possibly compromise the joints in the floor.

you have a good point, im just not trying to be to paranoid. Most areas are small like 4x6” and 7x12” gonna start with feathering and smoothing first before grinding out all 8-10 areas

 

[JPfloor]

you have a good point, im just not trying to be to paranoid. Most areas are small like 4x6” and 7x12” gonna start with feathering and smoothing first before grinding out all 8-10 areas

That should be ok…I think… Maybe.

 

[Incognito]

As long as you didn't over water the mix those ploymer additives should hold it to the slab and prevent it from crumbling. Take a 6" putty knife or any kind of scraper and see how well bonded and solid your thin-set is. Over time floating LVT molds/conforms to the imperfections of the substrate to some degree depending on thickness and if there's attached or other cushion allowed by the manufacturer. Myself, I wouldn't play around. Doing any sort of resilient flooring I would prep the floor to the texture of a wall that was getting paint or wallpaper. It's really easy for a pro to take it to that next marginal step when you're already 80-95% of the CLEAN/SMOOTH/FLAT/DRY/STRUCTURALLY SOUND specs.

I always would check the box-----All of the Above. (given the choice) I laid over whatever they told me so long as everyone bought into the risk and was well informed.

 

[JPfloor]

Take a 6" putty knife or any kind of scraper and see how well bonded and solid your thin-set is.

Good plan... If it’s stuck good skim coat over it with the 549.

 

[Gary_S]

Been hitting it with this scraper since it dried. So I’m pretty sure it’s all cured and secure. Nothing has busted loose When I scrape all the areas. It was a little wet when I did one spot and have to fix that with a grinder this weekend. As it stopped as soon as it hit dried and left some lines in a patch spot.

I was going to ask about covering in Henry 559 as well so thanks for that.

 

[Incognito]

overkill

let it dry

 

[Gary_S]

Should be dry, Thinset a week ago. Scraping 5-7 days ago

 

[Gary_S]

I want to thank you all for your help!! Started the grinder to feather the Thinset that was the original issue. Went like a hot knife through butter. Decided to grind out the rest of the Thinset and use the correct product. Lesson learned!! What a mess!! You be positive is the house got a good cleaning/dusting nothing to much as I’m sure I will cause another mess.

 

[driftinwoods]

I use quick set thinset all the time. Or old thinset I deemed out of date. Never have had a problem.
Even with SLC the sand is bigger than patch, about the same as thinset really. So I usually do the thinset and or SLC, scrape around the edges then hit the perimeter with real patch.
SLC usually leaves a good 1/8 bump around the edge. Gotta make sure you prime so the SLC flows. I even push it around with a trowel because I'm rarely looking for "level" as much as flat. Flat can have a pitch to it. A nice aluminum screed helps push it around.
I will usually start with a big dump at the top of a large dip I want to fill, pour a half a bucket at a time and pull my screed across the hole to the other side.
I do carry a 10' screed. Makes me lotsa money. Dips and high spots show up better than using a 6 ft screed.

Even some patch has large sand in it as compared to feather edge stuff.
If you hang around awhile after you pour SLC you can effectively knock down the edges with a clean wet trowel.

 

[JPfloor]

If you’re skilled with a trowel and screed, and don’t need the floor to be level why use SLC at all? I just use underpayment compound to get it flat. Dries faster too.

If I’m gonna pour, I’m gonna pour the whole room. Or build a barrier where the SLC will end. I use a rake with depth gauges to push it around. If you want the floor level the SLC needs a little depth for it to do it’s thing.

Homeowners who just pour a puddle here and there are usually just creating more work for themselves.

 

[Gary_S]

That’s why I figure SLC for my project is more work than necessary. The areas I have to work are between 1/16” and max 1/8”. I had finished the vinyl plank in another room and it dawned on me Henry’s is non sanded hence smoother and that’s what I had used.

One question though. Hypothetically Let’s say you had an area 12-18” circumference that was 1/8” low. Could you just trowel 2 vertical or horizontal rows 3 or 4 “ wide let’s say instead of filling in the whole area? If installing LVP. Like the level would not rock back and forth

 

[driftinwoods]

If you’re skilled with a trowel and screed, and don’t need the floor to be level why use SLC at all? I just use underpayment compound to get it flat. Dries faster too.

If I’m gonna pour, I’m gonna pour the whole room. Or build a barrier where the SLC will end. I use a rake with depth gauges to push it around. If you want the floor level the SLC needs a little depth for it to do it’s thing.

Homeowners who just pour a puddle here and there are usually just creating more work for themselves.

Because lots of times when I'm on concrete which is 99% of the time there is a trough across the room that could be 3 ft wide and a half inch deep. Thas just the way slabs here get screeded. By a crooked 2 x 4. ha! So it's easier to do it like I mentioned above with a screed and dump a pile of SLC and pull it across the trough. Works perfect. Takes a tenth less time that troweling.
And then there's really no reason to SLC the entire slab. Or yer gonna lose that bid rather quick. I ain't talking a 10 x 12 bedroom either.

 

[JPfloor]

Well to each their own I suppose.

I’d fill in that 1/2” deep 3’ wide trough the same way, with a screed and regular underlayment compound. Less expensive, no primer, less drying time, no touching up the edges…done... Same day install…Way faster.

If I’m gluing something down I’m skim coating the whole floor at least once anyway…Still same day install.

 

[Incognito]

If you’re skilled with a trowel and screed, and don’t need the floor to be level why use SLC at all? I just use underpayment compound to get it flat. Dries faster too.

If I’m gonna pour, I’m gonna pour the whole room. Or build a barrier where the SLC will end. I use a rake with depth gauges to push it around. If you want the floor level the SLC needs a little depth for it to do it’s thing.

Homeowners who just pour a puddle here and there are usually just creating more work for themselves.

yup

 

[JPfloor]

That’s why I figure SLC for my project is more work than necessary. The areas I have to work are between 1/16” and max 1/8”. I had finished the vinyl plank in another room and it dawned on me Henry’s is non sanded hence smoother and that’s what I had used.

One question though. Hypothetically Let’s say you had an area 12-18” circumference that was 1/8” low. Could you just trowel 2 vertical or horizontal rows 3 or 4 “ wide let’s say instead of filling in the whole area? If installing LVP. Like the level would not rock back and forth

You lost me there somewhere. If it’s just a 12” or 18” circumference why wouldn’t you fill the whole thing? That’s a pretty small spot? Ideally you don’t want any dips.

 

[driftinwoods]

By underlayment compound you mean patch? Like plani patch?
Not sure where you live but 1/2 inch deep fill don't dry here in an hour.
Depen depending on what floor is going in. Crapet yeah sure go for it. Wood no.
LVP with 6 mil prolly.
Most of my jobs are at least several hundred sf and I work alone. So there's plenty for me to do besides watch patch dry.
Plus I'm 67 years old. I'll pound out a few hundred sf and call it a day. I'm in no hurry these days.