Wood flooring: bouncing, not floating

[CrawfW]

Evening,

Pretty sure folks are going to enjoy telling me that this situation is a hopeless disaster, but here goes......

The 50m2 of engineered wood floor we recently laid to float on 5mm foam underlay is bouncy in places: clearly, the underlying substrate is not perfectly flat. Is the best (only?) solution to take it up and glue it down?

It moves by a few mm, but feels like more - what sort of variation will floor adhesive accommodate?

Can we glue onto the underlay (itself glued down)? Or must it too come up?

Got all sorts of other ideas (self-levelling in key areas, additional underlay, expanding foam), but figured that glue is the best option......

Finally, before i get completely ripped to pieces, this was done in a race to get a finance-stage released, without which all would have been over.

Crawf

 

[CrawfW]

So, the bounce didn't settle. Which means its time to start grinding.

I am hoping this will mean finding fairly small areas, especially at the edges, that are too high - rather than having to blast across the whole 50m2.

With this in mind, any thoughts as which of these would be most suitable?

https://ibb.co/cGMiY5

 

[Doggit]

How did you fit the engineered floor. Its should have been glued along the top edges, so are you able to get it up. Assuming that you can, then you need a 6ft spirit level over the floor to find the high and low points. If low, then you'd want feather edge self leveling compound, and if high, the grinder will work, but they chew up old aggregate based concrete, and you then need self leveling compund to then smooth it out afterwards.

If you can level the floor sufficiently, then you can glue the flooring down, but you wouldn't have any underlay underneath it. But what sort of underlay did you use, as that may be part of the problem; is the bounce on well used areas.

 

[CrawfW]

Thanks for your reply.

The floor is just floating, on top of 3mm Vitrex underlay from Screwfix - got good reviews. No gluing - should there have been?

In terms of why it bounces, i think it is because there are a few "high spots", that raise the rest. To get these spots, are saying that the grinding cup (option C) should be OK? With the thing to watch being that it will rip things apart and mean more self-leveling in required? (The self-levelling was a latex one, can't remember the make.)

Thanks again!

 

[Doggit]

If it's SLC you used, then the concrete grinder will just chew it up completely. They're great for fresh concrete, but pretty useless on old concrete. You may well find you can use a palm sander with 40 grade paper to take down the high spots, or possible a belt sander will do it quicker. Underlays are never glued down, so you did fine there.

But it still comes back to how you get the floor up first.

 

[CrawfW]

So, if the grinder is too extreme for SLC then the other two would be a big No No? Belt sander it is......

I used spray adhesive to fit the underlay - an error?

 

[Doggit]

I've even used a sharp chisel to take down SLC, so there are a lot of ways to do it. Some are just faster than others,

Well, you don't normally glue down the underlay, but I can't honestly say that it's an error. I tend to use 5mm fibreboard, as it's better insulation - that stuff can't be glued, and although they suggest you use packing tape on the joins, I find duct tape works better; although not much to be honest.