Can I lay my solid oak floor over a tiled floor?

[slowman]

Hi there

I've just moved house and have a (cold!) room with a tiled floor over solid concrete subfloor, which I was advised by the previous owner 'probably did not have a damp proof membrane under it'. I was planning/hoping it would be OK to lay a click together glue-free engineered wooden floor on 6 or 10mm underlay with incorporated moisture barrier straight over the top of the tiles.

However, a few days back we got offered a very good deal on 23m2 of 12mm thick solid oak flooring which I snapped up in the spur of the moment. What I am not sure about now is what I need to do in terms of prepping the subfloor and laying the solid oak floor.

You can see in the photos that the floor tiles are not laid with exactly flush edges - it's somewhat uneven. As for the overall level, there are some slight dips and a slight fall to one side of the room. It's hard to measure precisely because of the raised edges of some of the tiles, but I'd say it's only out by a few mm in any given place.

Can anyone experienced advise how I should go about this? Is it a case of needing a self-levelling screed over the top of tiles? If so what type is best? And what about underlay / adhesive, etc? Can I still lay this as a floating floor or does it have to be fixed down to the subfloor? I've never done this before.. I'm guessing the engineered wood might have been an easier option to lay..

Any advice appreciated...

Thanks

View media item 41119View media item 41120View media item 41121

 

[AronSearle]

12mm thick solid oak

12mm?


Solid flooring is best fixed rather than glued or floated.

You can probably lay a DPM, underlay and then float some 12mm+ T&G plywood, and then nail the oak to this. 12mm plywood assumes the nails will go in at an angle, and this is rather minimum.

But can you confirm they are 12mm thick, and their width (and I assume they are square edged?).[/quote]

 

[slowman]

Hi Aron

It is 1100 x 150 x 12mm solid oak from Homebase. It's got a slight bevel to the edges and a 'tap' together system. However it says glue is required. On the pack it says:

3 easy steps to a perfect floor:

1. Lay Homebase underlay and vapour barrier where required
2. Lay the floor using Homebase fixing kit, spacers and adhesive where required
3. Fit edging, threshold strips and pipe rosettes

However, I think they're assuming a perfect subfloor which I don't have. Also I take it from that they are happy for it to float - i.e. I guess they just mean to glue along the tongues of the boards rather than glue the boards to the subfloor... right? But like you say, I've seen comments on these forums that solid wood floors aren't meant to be floated. So I don't really know..

The main issue I am concerned about is how to prepare the tiled floor I have now. If I was to float plywood as you suggest over the tiles on underlay -

1. What kind of underlay would you recommend?
2. And is the purpose of the ply just to have something to fix the oak to?
3. If so, would I still not have a problem with the uneveness of the floor or do you think this will be lost under the underlay and ply?

Thanks for your interest..

 

[AronSearle]

Well, if the manufacturer says it can be glued and floated, then I would go with that and just make sure to follow their instructions to the letter.

The main reason I personally would prefer a solid floor to be nailed, is that it provides more restrain against cupping (though still not much), but also it allows individual boards to be lifted (though not easily, it's possible), once it's glued it's glued.


The purpose of the plywood is to provide an even surface, it would be able to span locally over dips in the sub floor (which would be further mitigated by an underlay under the ply (and another thinner one on top of the ply)). it's a quick and cheap way of doing it, some people use battens instead and plane them down in places to provide a flat surface. Obviously a levelling compound is a better way, but it is generally an unnecessary expense, and you may decide one day to revert to the tiles.


If you are going to float the subfloor, you can use cheaper T&G chipboard instead, 18mm would be preferable but less may be acceptable.

 

[slowman]

Hi Aron

RE the DPM / underlay - what would you recommend? A separate sheet DPM just laid down? Or those silvered rolls / boards taped together? What thickness would you recommend under and over the ply?

I've got about 30mm max to the underside of the fireplace hearth - you can see it lips out into the air, which I was hoping to fit the floor under and not to have to move...

 

[AronSearle]

3-6mm foam underlay with DPM

9-12mm T&G panel product.

3mm underlay (this can be thinner, as the panel should level the surface).

12mm floating oak boards.

=30mm



The risk is that a 9-12mm T&G panel may have a weak joint, and if the joint spans over a dip this may cause an issue, though the pictures you show make me think this will not be an issue.

 

[slowman]

OK thanks very much for your advice on that

You questioned 12mm - are you thinking 12mm is a bit substandard for a solid oak floor? That it might be prone to warping etc?

 

[AronSearle]

The width to depth ration has an effect on it's stability, and also how many times you can sand it (though that's generally not an issue for domestic use).