Oak flooring advice

[billybuntus]

Hi chaps,

I've given up on the pitch pine and bought 20 sq/m of pre treated oak T&G

Theres 5 random lengths 4 of which won't go between the joists.

I'm looking to take up the pitch pine floor and lay 12mm ply across the floor and screw in down then lay the oak flooring ontop of that.

Should this be sufficient, also should I glue the T&G together?

thanks,
steven

 

[billybuntus]

Update!

Would it be fine to use OSB sheets as opposed to ply? 12mm osb, as I have a few spare sheets and it seems to be as strong as ply.

After some more research on geekonet I believe I have to secret nail at 30cm intervals to the osb\ply floor? I'm hoping to do this by hand but I've no doubt I'll need to hire a tool for the job.

 

[OLD]

I do not have the correct info for you ,but you need a smooth sub floor with no unsupported joints that is glued and screwed to joists to eliminate creaking. That can hold the nails that fix the oak, others may know if something is required between the oak and subfloor

 

[Slim]

I would have thought OSB would be perfectly adequate. You will not be able to secret nail by hand. It only takes one slip of the hammer and your floor is ruined. You will need one of these

 

[Waka]

Steven

I have an oak T&G floor in my conservatory, I laid this as a floating floor because of possible movement with the temperature extreme in the summer. I did not use any glue on the joints and to be honest I don't think this is necessary, I think this is a bit over the top. If I'm wrong then I'm sure I'll be corrected.

 

[billybuntus]

Thanks for the info waka, the floor which I'll be laying on has a quite a bit of movement in it.

So you didn't nail it? just laid it like laminate?

If the floor was 100% solid I'd do the same but I'm hoping the flooring will brace the floor and give it strength.

 

[JFC]

You need your floor to be solid before you lay any kind of random flooring over the top of it . All your sub floor needs to be 18mm min and meet on every joist before you lay anything on top of it . Wood flooring , laminate etc is the waste from the prime timber and is not stress graded . with that and the fact that it is random lenghts means you can't use it to brace your structual floor . Think of your wood flooring as carpet and you will see what i mean .

 

[Waka]

Thanks for the info waka, the floor which I'll be laying on has a quite a bit of movement in it.

So you didn't nail it? just laid it like laminate?

If the floor was 100% solid I'd do the same but I'm hoping the flooring will brace the floor and give it strength.

If you already have a solid foundation i.e., floorboards or sheet flooring material then you could just lay the floor on a membrane. I didn't use any nails on mine and it has been fine for 4 years.

 

[billybuntus]

You need your floor to be solid before you lay any kind of random flooring over the top of it . All your sub floor needs to be 18mm min and meet on every joist before you lay anything on top of it . Wood flooring , laminate etc is the waste from the prime timber and is not stress graded . with that and the fact that it is random lenghts means you can't use it to brace your structual floor . Think of your wood flooring as carpet and you will see what i mean .

The flooring is solid oak, not a laminate.

would 12mm not be suitable?

 

[JFC]

It doesn't matter if its solid or not , unless you are using it to span the joists and land on each joist then you need a real floor before you lay the new one . You need the flooring to tie your joists together as much as your flooring needs the joists to bear on . I would leave the old flooring down and put 6mm ply on that and then lay the new floor .

 

[nickson71]

I'd do as JFC said ........... he's got it spot on as far as I can see

 

[billybuntus]

It doesn't matter if its solid or not , unless you are using it to span the joists and land on each joist then you need a real floor before you lay the new one . You need the flooring to tie your joists together as much as your flooring needs the joists to bear on . I would leave the old flooring down and put 6mm ply on that and then lay the new floor .

The old floor is knackered and swmbo wants a blanket box made out of the old floor.

So take up the old floor and put 18mm down yeah?

 

[nickson71]

If the old floor is that knackered I'd take it up and put new 18mm down ........... but you need to make sure that the joist are fine

as to my mind if the excisting floor is not good enough for a 6mm ply top and then a new floor then there maybe a more serious problem

 

[billybuntus]

If the old floor is that knackered I'd take it up and put new 18mm down ........... but you need to make sure that the joist are fine

as to my mind if the excisting floor is not good enough for a 6mm ply top and then a new floor then there maybe a more serious problem

I'm aware of the problem with the floor in that the joists are only 6 x3 at 600mm centres over a span of 4.5 Metres

Current regs are 400 mm centres? with 9x3 joists over around 3-3.5 m span (approx) with T&G flooring.


The floor has dropped around 1/2 inch in the centre over about 30 years, the floor has quite a spring in it if you bounce up and down in the centre.

I know the real answer is to replace the joists or one suggestion has been to jack the floor up from downstairs and strengthen it with steel plates tied into the walls and bolted to the exisiting joists (sandwiching the joists with the plates and bolted at 400 mm intervals).

The trouble is that battens are attached to the joists which the plasterboard is pinned too which gives me very little room to put anything worthwhile in.

I'm loathed to take the floor out as obsviously it means massive work to replace the joists and ceiling and we don't have that much time and I don't have that much experience to be honest although if I had enough time I'm sure I could do most of the work.

The pitch pine is also very wide, no t&g and not in very good condition (many have split across the full length of the board).

I'm confident that the floors not going to collapse or anything as its been like this for as long as the previous owners can remember. And once it has a decent floor down over the joists I'm sure it'll add alot of strength.

 

[OLD]

This is developing have a look at this http://www.diydoctor.org.uk/projects/load-bearing_walls.htm


I read it as beams should be 220x75 at 600 for a span of 4.64m for the current regs.
So you could put in lots of noggins and still have some bounce, or put extra beams along side and fixed to existing beams what size these should be is not available from the table and proper advice is required.

 

[billybuntus]

Existing floor







the new oak flooring 20 mm thick 4 sided t&g

 

[JFC]

18mm ply would be a good idea if you are taking up the old floor , make sure you stagger the joints so you are tying the joists together . As said above it wouldn't hurt to put in some noggings or double up the joists but if it has been like it for the last 30 years i doubt it's going anywhere .

 

[billybuntus]

18mm ply would be a good idea if you are taking up the old floor , make sure you stagger the joints so you are tying the joists together . As said above it wouldn't hurt to put in some noggings or double up the joists but if it has been like it for the last 30 years i doubt it's going anywhere .

Excellent, any reason for choosing ply as opposed to osb?

I'll try to strengthen the floor as much as possible by putting in noggins but I won't be able to put additional joists in as there is not enough space.

Would really love to put the additional joists in but hey hoe such is life.

 

[nickson71]

In term of additional joists you may want to look at sistering the joists ..... this basical strengthens and stiffens the existing joist .......... try googling it the first hit I got was here

you could do this and add more noggins and it will strengthen the floor


hope this helps

Ian

 

[billybuntus]

In term of additional joists you may want to look at sistering the joists ..... this basical strengthens and stiffens the existing joist .......... try googling it the first hit I got was here

you could do this and add more noggins and it will strengthen the floor


hope this helps

Ian

Thats what I meant by adding the steel plates, aha so there is a term for it!

Its amazing you know, I've had three builder out all from different backgrounds and one with a wealth of experience and they all just scratched there heads and said it must be woodworm thats weakend the floor we'll have to replace it!

Oh well, I'll be adding as much support as I can fit in under the floor but jacking it up isn't an option (SWMBO worrys too much).

Thanks for the info chaps, I've got a week off soon so I'll start then.

I'll keep you posted on how I get on.

Thanks for all the help this really is a helpful forum,
steven