Floor on top of an existing floor?

Situation: existing floor is okay(ish). Some damage due to environment and previous owners, looks cheap(ish), colour doesn't match new living room layout & theme. New floor is only 1cm (10.5mm) thick, and perfect for our needs. What would happen if the new underlay (2mm thick) plus the new floor is installed on top of the existing flooring? Beside the obvious loss of 1cm from the room. No skirting board installed yet (been removed in anticipation of the re-work).

Would it work and would have all the insulation benefits for which I am willing to sacrifice the 1cm loss from the room height for?

By no means am I an expert but here's a warning from experience - 1cm might not make much difference to the room height, but you might end up rehanging some doors. >,<

What is the existing floor? Suspended, solid? Ground floor? House, flat?

2mm isn't much in the way of thermal insulation. If it is a suspended floor you would be better off lifting the floorboards and putting in insulation between the joists. If it is a solid floor, you have fewer options. How old is the property?

Around 50 years or so (maybe less) can't check the papers right now.

Ground floor, solid. The existing flooring is laminate. Forgot about the door rehanging but that shouldn't be a problem.

I was discouraged by some people to use 3mm or thicker underlay for flooring cause it "may" render the new floor spongy. Including an floor installer.

EDIT: should I go for a 3mm underlay with thermal insulation (silver) layer? Or keep the underlay (whatever that may be) from the existing flooring?

Any insulation is better than none, but considering that modern builds use at least 50mm of underfloor insulation...

I'd probably replace what is there, you don't know how long it has been down, and it does tend to compress with time. It is true that too thick underlay can make the floor feel spongy, and I think the real reason for the underlay is to allow for differential expansion between the flor and substrate as well as making it feel warmer to bare feet. But in terms of the overall energy efficiency of the house, it probably won't make a lot of difference. However, home insulation is not my field of expertise!

I'm no expert in these matters, but with that in mind and further to comments made above by others and by yourself, I would say that firstly, if the existing flooring is cheap and of a questionable quality, can it be trusted to withstand being sealed in by another layer of underlay above it and then another layer of flooring?

I'd also be thinking about how much more it would cost you to remove your new flooring in order to address an issue that develops in the old flooring following the installation, ultimately it might well prove a more sensible solution to put the extra effort in now in order to save repeating work later and then having to replace the new flooring at a greater expense in order to fix things.

I would think that for a house built in 1965 ish, there is a re-I forced concrete slab enclosing do by the external walls, with the internal walls built off it, and with minimal insulation, but it would be difficult and expensive to dig that up and put insulation in. Today there would be a layer of polystyrene or similar in the concrete, and that would be at least 20mm thick, maybe more. For a suspended floor, the insulation can be the thickness of the joists.

But I agree with keyboarddemon that you would be better to take up the existing floor and start again from the bare substrate. It gives you a clean sheet to work from, and will reduce the chance of squeaks as the multiple layers may rub together.

remove it and start over.

you might find it's lined with £50 notes.....

I would take it up and start all over again, you know then its all good and if it were me 12 months down the line I would be thinking I should have got it up.

It's almost like should I paper over old wallpaper, works out expensive if you leave it on and later it starts to bubble and peel off.....

Your call

Old flooring was removed, underneath were fiber boards + felt in great condition, so they stayed plus 2mm underlay and top of it the new flooring. Feels great!

Sadly, no stashed money was found :(

Glad it worked out (apart from the money! :D)

The moneys probably under the fiber boards.......

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Originally Posted by Bonebreaker777

I was discouraged by some people to use 3mm or thicker underlay for flooring cause it "may" render the new floor spongy. Including an floor installer.

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We just had some laminate laid and used green squares of fibreboard underlay, it was around 6mm thick if I remember. Is a bit spongy at first but it settles down after a few days walking about on it. It feels fine to me, a bit more cushioned than the thin 2mm foam stuff we had before plus there seems to be less "drumming/echo". We are happy with it.

This all reminds me of an old Victorian house we bought and renovated circa 20 years ago. In the sitting room we had a carpet covered floor over a standard ventilation void, which we wanted to get back to the boards to sand and varnish. We had taken it off the hands of an old farming family and found we needed to take off six different layers of carpet and lino, and after that opened out polythene fertiliser sacks that had been nailed to the floor with galvanised clouts!

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Originally Posted by RobbieRoy

and after that opened out polythene fertiliser sacks that had been nailed to the floor with galvanised clouts!

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Probably kept the bugs at bay with the fertiliser sacks ?

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Originally Posted by Tropheus

The moneys probably under the fiber boards.......

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this...

get that new floor up and CHECK... you'll always wonder.... ;)

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Originally Posted by Zak33

this...

get that new floor up and CHECK... you'll always wonder.... ;)

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Haha, forgot about this thread for a second. It's finished. Below the fibre boards there was only the original base before my time even. Black tiles from the council. Nothing else. Top of it fibre board. On top of that 2mm foamy underlay. On top of that the engineered flooring. It's rather fab, if I may say so and don't look like a fairy :D

I'm also new here and I'm looking forward to learn from you guys.


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