OSB3 vs Ply vs floor boards - Please help!!!

[Hl.house]

Hi all, we have have ripped out the old floor boards(too old, broken and split) for a first floor bedroom and are now at joist level. For new flooring I will need approx 10 sqm or 4 sheets of 1200mm x 2400mm. My options are:

1) OSB 3: what thickness? 18mm +? Cost around £75
2) Ply, exterior grade WBP: 18mm + ? Cost aorund £100
3) Floorboards: whitewood T&G, 22mm thickness or redwood square edge 25mm thickness? Cost from £140-250.

Questions:
1) Do OSB, ply and wood boards become structural at a thickness greater than 18mm or is there any other criteria?
2) If I use ply, can i Just finish it with 3 coatings of polyurathene or will I need other flooring on top? Ignore the aesthetics for now. Will I need to sand it before sealing with polyurathene.
3) Floor boards, again Can i just seal them with Polyurathene or do I need any other flooring on top?
4) Finally, can i put some earthwool insulation in between the floor joists?

Chip board is also an option but I am not sure if it is better than the 3 above.
Please help.

 

[williamglossop]

Is it gonna be your finished floor or are u covering it?

 

[John D v2.0]

18mm is enough for 400mm centres, but if your joists are wider you'll need thicker. Larger boards are good because they share the load both ways.
And insulation will only be needed if you have unheated space eg garage underneath. If so wool will help.

 

[Hl.house]

Is it gonna be your finished floor or are u covering it?

If we use OSB then no. We will need other floor covering.
If we use ply can we seal it off with 3 coats of polyurethane? Does it need to be sanded?
Floorboards are planed and smooth so no need for sanding, right? Just seal it with 3 coats of poly urathene? Do I need to do anything to fill the gaps?

 

[Hl.house]

18mm is enough for 400mm centres, but if your joists are wider you'll need thicker. Larger boards are good because they share the load both ways.
And insulation will only be needed if you have unheated space eg garage underneath. If so wool will help.

Space between two joists is approx 37-38cm.
We have kitchen under this room. Both kitchen and this room have 2 external walls. I am trying to insulate the room as much as I can.

 

[Hl.house]

For aesthetic reasons I like floorboards.
For money reasons OSB.
For moisture related problems ply seems to be better than OSB.

Any other things I should be aware of.

 

[endecotp]

4) Finally, can i put some earthwool insulation in between the floor joists?

Chip board is also an option but I am not sure if it is better than the 3 above.

Insulation between joists can be useful as soundproofing.
The main advantage of chipboard is that it is cheap.

 

[Hl.house]

Insulation between joists can be useful as soundproofing.
The main advantage of chipboard is that it is cheap.

How is Chipboard quality?

 

[Hl.house]

Does ply contain formaldehyde?
Is OSB3 free of formaldehyde?
Apart from aesthetics do floor boards have any advantage over ply/OSB?

If budget is not much of an issue which one would you choose and why?

 

[JohnD]

It's everywhere...

 

[endecotp]

If budget is not much of an issue which one would you choose and why?

That would depend on what final floor covering I wanted. I.e. carpet or not, mostly.

 

[JohnD]

for me, hardwood-faced ply.

Strong, rigid, smooth, flat, doesn't crumble when you walk on it, few joints, tight square edges.

And if the fancy takes you, you can dye it with Colron and varnish it.

If I was going to have a room with an exposed floor, I would go for solid hardwood boards, and insulate between the joists.

Chipboard is at its best on a bonfire.

 

[Gerrydelasel]

If budget is not much of an issue which one would you choose and why?

1) T&G floorboards -look nice, accommodate wonky joists more easily, less likely to creak, easier to access stuff underneath, but inconvenient if you want anything but carpet on top.
2) 22mm Ply -Good coverage, less moisture resistant, but smooth and flat so great for coverings.
3) OSB or chipboard when money is an issue.

 

[Hl.house]

Carpet definitely a NO-NO. Bad for asthma/respiratory allergies.

Love the exposed pale wood floor look. Pics below. But don't want to do it if it involves too much heavy work(sanding). It will be difficult for me to take the heavy sanding machine upstairs.

 

[Hl.house]

I also like the polished concrete/concrete wood mix look . But it is probably a no no in period property with suspended timber flooring, I suppose.

Something like this -