Repairing LVT flooring

ThisIsWeird

Very possibly.

I think it may come down to what is causing the movement, whether it's an isolated low point in the sub floor, or actual flex in it. If 'flex', then I guess the problem will continue. If it's just a localised low point, then adhering this could very possibly sort the issue.

The alternative is a complete removal, sort, and redo?

fiish

What would you mean by 'flex'? If you mean that jumping up and down on one part of the floor causes the floor a metre or so away to move, that doesn't seem to be happening.

But it does seem like the sub floor is soft in a few points, which also coincide with where traffic/use seems to be heaviest.

ThisIsWeird

Is the movement is due to a gap between the flooring and the joists below, then the solution is to fill that gap. That could be done as 'easily' as adding a thin sliver of wood or similar to the top of the joist so it now matches its neighbours, or by screwing and addition timber alongside the low joist, but set fractionally higher so's it matches its neighbours.

By 'flex' I mean that that actual joists themselves are moving, bending, might not be adequately supported, or be weak so that they move. Clearly adding a sliver to that won't help - it'll still move. The solution will depend on the cause, but if it's 'weak', then again adding a sister joist alongside should help.

Doozergirl

That type of flooring needs a perfectly level surface underneath.  It will not forgive anything.  It's not suitable for large areas either as you get more movement across a wider area.  

I honestly think this type of flooring will disappear from the market.  Because it clicks, people interpret is as being like laminate but it isn't.   It's more or less being sold like it on the website.  

The fitting instructions aren't attached to that webpage but the sales page does say it needs to be fitted in accordance with them to avoid voiding the warranty. 

Looking elsewhere for actual instructions for 4mm SPC I read this "The surface must be levelled, maximum height differences of 3 mm per linear meter."   One sentence in a full page dedicated to prep that voids the entire warranty.   Some people could have that between two floorboards, let alone over a metre.  

To get that subfloor, the prep for it is basically identical to the work required for glue-down LVT - 18mm ply and a feather finish over.  This stuff is sold on being easier to lay but there's a huge amount of work in the prep.  

fiish

As far as I can tell, there's old wooden floorboards over the joists, there's a utility cupboard off the room where the floorboards are visible, and over there, at least, the floorboards seem solid and don't move at all. Any 'give' in the LVT flooring seems to be coming from the soft foam underlay forming lots of localised low points.

Definitely not level.

Have spoken to two flooring installers now, both have said that large areas of the flooring, if not the whole room, need removing, even if just to replace the damaged tiles. I'm wondering whether to just replace with a more suitable flooring type while I'm at it, otherwise it sounds like it's just going to break in the same way again before too long.

Any advice on more suitable options? I'd like to retain the original/old timber floorboards if I can, would consider LVT over plywood as suggested above, but might engineered wood or tiles work better?

Doozergirl

Anything floor covering will will work if you lay the subfloor correctly.  

That usually goes over the floorboards - it would unusual but not uncommon to remove them.
 

Engineered wood probably needs the least prep.  

fiish

Thank you for the advice!

I have been quoted just over £2k to take up the flooring, replace the subfloor (laying plywood in this case), and then re-lay the flooring, with any damaged tiles replaced from the spare supply. For that cost in both money and disruption, we're probably not going to rush into it just yet. 

benson1980

fiish said:

Thank you for the advice!

I have been quoted just over £2k to take up the flooring, replace the subfloor (laying plywood in this case), and then re-lay the flooring, with any damaged tiles replaced from the spare supply. For that cost in both money and disruption, we're probably not going to rush into it just yet. 

Sounds like a plan. I agree with Doozer- not a fan of the click vinyl stuff. Glue down in my opinion looks and feels a lot nicer underfoot. Karndean looselay is another option- thicker tiles and could probably lay straight on ply overboards without skim coating it with smoothing compound. Plus, if you do need to access under the subfloor for any reason (e.g. if any pipework is under there), it is easy enough to take it up and relay it.

fiish

I managed to find time to have a closer look under the LVT again, by opening up one of the screwed down thresholds under a door.

It looks like there's actually ply over the floorboards already, not very thick (about 9-10mm). Then 3-4mm thick foam underlay, and the 5mm LVT (which has its own built in underlay) on top of that.

From what I've learned from your replies, it sounds like the underlay is the main cause of the problems, as heavy loads probably caused it to compress in spots, leaving the LVT unsupported and susceptible to stress when trodden on.

From what I can tell, the underlay was probably put in to compensate for the thin tiles. The adjoining hallway is tiled, so the LVT floor would have been a few mm lower than that if the underlay had been omitted.

Is it necessary to have underlay over the ply boards before laying flooring on top? I was thinking of using thicker/larger flooring tiles (either engineered wood or Karndean/Amtico) laid directly on the ply, to avoid changing the floor height too much, but is that a bad idea?