Yet another wood block flooring question

[ballywho]

I have a quantity of salvaged oak blocks, 500mm x 70mm x 19mm. They have a groove about 3mm wide and about 10mm deep running around all 4 edges. They were previously mounted with bitumen, but the bitumen was planed off before I got them.

I want to lay them in a herringbone pattern in a second floor bedroom 3m x 4m. The base is a concrete screed (put down 20 years ago), It seems to be about an inch thick over some sort of wood subfloor, the whole lot supported by 100 year old oak trusses.

I am a competent DIYer, but want some advice because this application seems a bit different to the dozens of others I have read about on these pages.

Is the groove in these blocks intended for some sort of biscuit or jointing strip? If so, what should I use?

From previous advice here-abouts, I like the sound of Elastilon, is it the right product for this application?
If not, what technique is best? The room will be subject to a fair range of humidity through the year, I am a bit nervous of gluing down, as I have recent experience of a (professionally installed - or so I thought) oak floor which tends to cup in summer.
If I go with a floating floor, I imagine that the blocks need to be interlocked?

 

[mac391]

500 x 70 x 19mm ??? you could almost call them planks !!

Never seen parquet flooring with a groove on all 4 sides, it's usually T&G and if they were previously laid in bitumen, they wouldn't have been made for biscuit jointing which would take forever to install.
You can buy the tongues but not sure where, maybe someone will come up with that answer..

The usuall way to lay is by levelling the concrete with a screed then use wood block adhesive and fully bond down. You will have inevitable gaps that you fill with the sanding dust (you will need to sand after installation).. How this would work as a floating floor on elastilon i'm not sure but sounds like a bad idea to me..

Why you have concrete over a wooden subfloor on the 2nd floor is a mystery ?? are the joists strong enough to take the added weight considering their age? and what dimensions are they ?

 

[ballywho]

Thanks for the reply.

I don't know why the concrete is there, it would be a lot of work to pull it up, for not much benefit. It looks fairly flat and level, but I will measure carefully before proceeding.

Is your doubt about the suitability of Elastilon due to the need to sand and finish the blocks? or something else?

Assuming that it is flat, I was thinking of using strips of 3mm ply to convert the blocks to T&G, over Elastilon. Around the edges of the room, I would have 2 rows of blocks parallel to the walls.

 

[mac391]

Yes Elastilon is sticky on the upside only (unless there is a new breed i don't know about) so it doesn't adhere to the subfloor.
Trying to sand your parquet on top of this, on top of a concrete suspended floor doesn't sound good. It might work but probably not.

Either way, it's a bad idea to use underlay for parquet if you want it to last..