Laying LVP over existing Engineered HW

Hello All,


I am contemplating laying LVT over my existing engineered HW flooring (glued down), and know that it's definitely doable. However, this house has a pretty sizable dip/deflection where the kitchen flows into the living room. If you look at the pics attached (sorry about the dog hair ), it's about a 5 ft. span, and just about 5/8 inch at the deepest point. We had a foundation company install intellijacks beneath in the crawl space, and have tried to iron it out from the bottom up unsuccessfully so far (they say it can take up to 3 years and multiple adjustments etc., and still potentially wouldn't be perfect), but at least the joist is now supported. With that said, how would you go about dealing with this dip? Is the answer to put some self leveler there before laying the LVP? Or would it be ok to lay the LVP right over it etc, and it would conform? Keep in mind that when I install the new floor, it will be laid over the current direction of the engineered HW in a perpendicular fashion.

Any advice or suggestions? I certainly don't want to have to wait for these jacks to continuously be adjusted as these floors need to go! Thanks!

I would go downstairs, or underneath the house, and see what’s up with that dip in the floor. Did some joists get cut for whatever reason? Maybe the foundation is sinking? I would want to at least know the reason, and attempt to fix it, before I just went ahead and filled the dip.

Now as far as laying over hardwoods goes, we used to do it all the time until the rules changed. When you lay a floating floor over top of hardwoods you’re preventing the free travel of moisture. The floating floor acts as a vapor barrier of sorts and moisture that would normally pass through the floor can get trapped in the wood floor thereby making it grow. I know ripping up some glue down hardwood doesn’t sound like fun but that’s what a lot of manufacturers are now recommending. If the hardwood floor cups, crowns or otherwise buckles, your floating floor is in trouble.

C.J. said:

I would go downstairs, or underneath the house, and see what’s up with that dip in the floor. Did some joists get cut for whatever reason? Maybe the foundation is sinking? I would want to at least know the reason, and attempt to fix it, before I just went ahead and filled the dip.

Now as far as laying over hardwoods goes, we used to do it all the time until the rules changed. When you lay a floating floor over top of hardwoods you’re preventing the free travel of moisture. The floating floor acts as a vapor barrier of sorts and moisture that would normally pass through the floor can get trapped in the wood floor thereby making it grow. I know ripping up some glue down hardwood doesn’t sound like fun but that’s what a lot of manufacturers are now recommending. If the hardwood floor cups, crowns or otherwise buckles, your floating floor is in trouble.

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Thanks for the reply CJ - I hired a foundation company to iron out that dip, and they placed jacks/footers in the crawl space below which have been adjusted a few times not bringing it up much over the past 2 years.

I hear you regarding ripping up the flooring, I battle with the idea and haven't completely ruled it out. It's just that either way, even with the jacks down there, the floor is being stubborn and doesn't want to budge which is why I'm considering some other method of leveling....

One thought I had was to cut out and demo just that section that's 5/8" low and layer shims/felt/ply to flush out back to the remaining level. My top layer would be 1/4" underlayment. That seems simpler than trying to JUST shim/felt/ply on top of the flooring to flatten that gully.

Of course you'll have to consider what sort of moisture that hardwood is subjected over 4 seasons to because it's theoretically possible to cause warping and swelling if yout plastic floor seals over what has been a happy MVER. So long as you're sitting high and dry there would be no issues there.