# Preparing floor before placing lay flat vinyl planks?



## papakevin (Mar 14, 2017)

We had a contractor add a sunroom on the back of our house and we said we would install the finished flooring.  We have a bunch of lay flat vinyl floor planks and I'm wondering what we need to do to prepare the subfloor for installation.  It is the standard interlocking 3/4" subfloor, nothing fancy. 

My question. Do I need to prepare the surface in any way prior to install of the lay flat vinyl planks?  I'm thinking about using something to fill in the gaps, where the floor seams aren't totally tight.  I was also considering applying a layer of Redgard on top of the subfloor before installing the floor, but didn't know if that was overkill.  The room does not tie into the house HVAC.   Appreciate the help.


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## slownsteady (Mar 14, 2017)

As long as the floor is flat and level, you don't have to do anything. You might choose to fill the gaps if they are wide, but you may want to leave a small seam for expansion/contraction. You should be reading the Mfr installation instructions for acceptable seam size and (since no floor is absolutely flat) tolerance to high and low spots. Is it a floating floor? And is it click-lock or grip-strip?


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## papakevin (Mar 16, 2017)

View attachment ImageUploadedByHome Repair1489669480.383462.jpg


The flooring is lay flat vinyl, no click lock.  It's thick stuff which is supposed to lay flat and be held in place by the other pieces. You can apply tacky glue around the edges and high traffic areas to help keep it in place if necessary. I've never used it before. 

Here's a photo of the floor now.  I was thinking since there is no HVAC in the room, I would give it a coat of Redgard before putting down the vinyl to help keep moisture out.


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## inspectorD (Mar 16, 2017)

I would suggest that you do not use redguard under the vinyl floor. It may creat a double vapor barrier which is a no no., and an overkill.
It does not go on smooth and cost will be way more than what you need to spend.

Buy some self leveling compound and fill the joints.. and any low spots .
Good luck., Have fun.


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## mabloodhound (Mar 16, 2017)

That wide gap in the floor picture definitely should be filled.  As Insp D said, use some self leveling compound.
I would use some sort of glue or tape to fasten the flooring to keep it from moving.  You could use carpet tape to fasten the underside edges of the vinyl to each other BUT not to the floor.  This would allow for expansion and the entire system would then "float" as a unit.


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## bud16415 (Mar 16, 2017)

My firsthand experience with lay flat vinyl is don&#8217;t use it where there is sunlight and shade. My nephew laid a large area with a dark color vinyl and could not keep it in place. The sun would come in and heat spots and the stuff would expand and shove the rest around when it cooled down he had irregular gaps everyplace. He took it all up and redid it a few times and then he got rid of it. 

I have heard other reports about this and not saying yours will react like that but I would ask the question before laying it.


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## mabloodhound (Mar 16, 2017)

bud16415 said:


> My firsthand experience with lay flat vinyl is dont use it where there is sunlight and shade. My nephew laid a large area with a dark color vinyl and could not keep it in place. The sun would come in and heat spots and the stuff would expand and shove the rest around when it cooled down he had irregular gaps everyplace. He took it all up and redid it a few times and then he got rid of it.
> 
> I have heard other reports about this and not saying yours will react like that but I would ask the question before laying it.



Yeah, that is exactly why I suggested taping all of the planks to each other so they could float as one unit.


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## bud16415 (Mar 16, 2017)

mabloodhound said:


> Yeah, that is exactly why I suggested taping all of the planks to each other so they could float as one unit.



If I remember right my nephew tried that even with one of the redos. 

The OP mentioned gluing high traffic areas. I would worry about attaching it here and there as the floor then cant float and will buckle.


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## papakevin (Mar 22, 2017)

Thanks for the heads up guys.  I already have the product and cannot return. Will probably give it a go this weekend.


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## papakevin (Mar 22, 2017)

What's a recommendation on an easy to use self leveling compound to fill the joints in the subfloor?  I have both a Home Depot and Lowe's nearby.  Thanks.


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## slownsteady (Mar 23, 2017)

If you are just filling the seams, you don't really need a self leveling product. Just run it in with a putty knife


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## bud16415 (Mar 23, 2017)

:agree:

I would just get the bag mix and mix it in a bucket a little at a time and mix it thicker than you would to pour it out. Then put it on with a wide putty knife as SNS suggests or I use my drywall mud trowels / knife. If there is a tiny step just feather it out.


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## papakevin (Apr 24, 2017)

Update.  The lay flat vinyl planks seem to be working well.  I did not glue them, just dropped them in place.  Here are a few photos of the room, although the wife has covered most of the floor with rugs.  

Note, we added this spare room / sunroom so we could keep our 17 month grandson in a smaller, easier to contain area.  View attachment ImageUploadedByHome Repair1493091713.785355.jpg
View attachment ImageUploadedByHome Repair1493091723.186259.jpg
View attachment ImageUploadedByHome Repair1493091731.632056.jpg


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## mabloodhound (Apr 25, 2017)

Looks good.  And if they're not glued it is easy enough to change one out if it gets damaged.


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