LVP and Underlayment Questions

[Adam Sharp]

What is the general consensus out there given the two options below:?

LVP with underlayment attached

OR

LVP with detached/seperate underlayment?

I'm leaning towards this combination for my condo project:

LifeProof LVP w/ Underlayment atop Quietwalk Underlayment

Is that overkill? Can anyone provide the tried and true most cost effective method? My rationale for going the route above is that I know as an amatuer I will only be able to get the floor "SO" level and this would give me the most room/cushion for error and hide more imperfections. Added benefit is it will stay warmer during Seattle winters. The manufacturer says NO underlayment with the LVP linked above (voids warranty) but is this a real concern?

Thanks!

[Brian Beck]

The LVP flooring nowdays is a pretty durable product.   What are you installing it over, concrete or wood?  We have installed probably 50 to 100 of these over the last year on both types of subfloor with no underlayment and have had no issues.   The safe bet is to follow manufacturer instructions on the chance you should ever need the warranty (even if the warranty issue is unrelated to the underlayment if they come out to inspect it the underlayment will void any and all warranties per most manufacturers.  How far out of level is your flooring?

[Adam Sharp]

@Brian Beck - my condo is 50/50 slab on grade / joisted durock. The slab flatness is great but I’ve got a major banana bow (1”) in the joisted section along with about an inch to makeup where it transitions. I will probably try to level the joisted durock section with some thin plywood but know I won’t be able to do a “perfect” job. So I’m trying to give myself some error margin and added insulation by going w 2 layers under (the attached + 1)

[Keith Lewis]

While either way is good I'm going to pass on two situations that occurred with one of my clients. They had installed CL floor with attached pad. There was a water event. Water was removed everything seemed okay. Within a few months the plank began to develop black lines at the edges. After further investigation it was found that this was mold growing up through the locking joint. Now while nothing might have stopped the mold a separate pad would not have a seam if it developed under the pad. The chance of it growing on the pad was probably minimal since it had nothing to feed on.

The second situation was one where the CL floor was installed over a parquet wood floor in a basement. The manufacturer suggested a plastic sheet moisture barrier between the wood and the new floor. Months later after the consumer returned from a trip the CL floor was heaving. Further investigation found that the barrier has trapped the moisture and caused the wood floor underneath to buckle.

You really need to know your situation before installing CL floors. Get a non invasive moisture meter and  a laser thermometer. you total investment will be well under $75 but you will use them constantly to keep yourself from being a victim.

[Brian Beck]

@Adam Sharp how are you attempting to level the bow? If its atop the durock you could use mortar or or leveling cement, just need to ensure it fully dries and cures before placing the vinyl atop it, this would leave it pretty flat and ready for the vinyl

[Adam Sharp]

@Brian Beck My initial thought was to fill the low spots with floor mud and or leveling cement, then lay a thin sheet of ply on top - Followed by thin floor mud in the seams.

[Brian Beck]

@Adam Sharp I think if you do a solid mortar bed to level out the low areas I dont think you'll need to do the rest as the mortar should sit level on it's own and provide the solid backing needed

[Keith Lewis]

There isn't a locking/floating floor on the market that will give a variance of more that a 1/4" on a 10 foot span. And a portland based floor leveler requires you to normally mix in some type of pea stone if you are going over 1/2" and up to 1 1/2" . Anything more than than you need concrete patch. read the bags for the thickness they allow and realize that you will need time for them to properly cure and get the moisture out before laying any floor floating or otherwise ; to avoid either mold developing or the moisture breaking the bond of the glue. 

[Adam Sharp]

Finished up the floors!

[Adam Sharp]

Hi all - thanks for all the help and advice on this project, it came out great for a first timer :)  I've attached some photos for all you you to take a look at the finished product.

A few notes / lessons learned for me.

1. i used self leveling concrete to make up for a lot of discrepencies in the floor.  I think i mixed it a little thick - next time i will make the mixture more runny so it spreads out a little better.  There was a little wall/dropoff where the leveling compund ended and the original floor remained so i had to use floor mortar to feather it down....still when walking on the new LVP, i can tell where the dropoff is/was.

SO, next time i will 1. make the SLC more runny, 2. on a small job (500sf) ill plan to cover the entire space with the SLC so there are no transitions, and 3. the LVP with the underlayment attached seemed to work great on the portion of the floor that was on slab, but feels cheap to walk on in other areas - so next time i will most likely go with a product that allows a thick underlayment to go own underneath it.

The last thing i learned was that the 1/4" gap around the borders that is recommedned is too generous as it is almost impossible to hit on the nose.  I laid down 1/2" baseboards and have some gaps in places...next time i will shoot for a tighter fit around the borders.

All in all, great project, and I got to buy a brad naller and a chop saw for this one so I am happy as a clam.

Thanks again for all your wisdom and advice BP Community.  I couldnt have done it without ya!