Yellow tongue/red tongue particleboard - joists all over the place!

[TCX]

OK, I'll admit it, I stuffed up! I'm about to replace my kitchen subfloor (hopefully salvaging the original 1920s timber along the way), and went under the house and measured the easily accessible joists to check the spacing. Those joists were at (or less than) 450mm centres, so "marvellous", I think, and buy up the requisite amount of yellowtongue particleboard. Now having actually gotten some old floorboards up, it seems that my aged house suffers from "random joist spacing" syndrome, and I have everything from 400mm to 600mm spacing (could still be more in the areas I can't see).

So - given that I don't want to waste several hundreds dollars worth of y/t board, what are my options? If the average spacing is 450mm, across 4.5m, is that good enough? If not (or if the average is over 450mm - I can't see all the joists yet so anything is possible), what can I do? (Please don't say "Get more stumps and joists" - I think I'd give up now!). I've read lots about reinforcing/sistering joists, but I assume this just reduces deflection along the length of the joist, not deflection/support of the particleboard between the joists. Would putting noggins between the offending 450mm+ spaced joists be sufficient?

Am a bit stumped (no pun intended) as I don't plan on doing any other floors and don't really want to waste the yellow/t I have and replace it with red/t.

Thanks all - looking forward to your miracle cures!

Tania.

[Vernonv]

No miracle cure sorry ... but what about putting in an extra joist where the spacing is greater than 450 i.e. if the spacing is 600 then put a joist down the centre of the span (parallel) and effectively split the spacing into 2 lots of 300?

How many are above 450?

[echnidna]

If the max spans are 600mm use red tongue throughout

[TCX]

Not sure yet how many are over 450mm, but will soon know once I get the rest of the boards up at the weekend!

How do I "put in another joist" - does this involve new stumps/piers? Will do if necessary but would really rather not! What is done on old houses where the spacing is over 600mm and even red tongue isn't sufficient?

Looks like I might be reading up on installing stumps before I get on with floor laying then?!

T

[Vernonv]

The joists sit on the bearers (I assume that is the case in your situation), so you shouldn't need extra stumps.

If you are ripping up the floor you should easily be able to drop in extra joists, just make sure they are the same height as the existing joists, so the floor will be level (flat).

A photo of what you have might help.

[glock40sw]

What sort of floor are you going to put over the Y/Tongue? 19mm T&G?

[TCX]

Well now I'm confused - I thought the joists WERE the bearers - as in, they "bear" the load? OK, which ones are the bearers?!

No photos yet as the floor isn't up and so I can't get a good shot - will add one after the weekend (if I don't decide to avoid it all and go to the pub instead!)

After the particleboard is down it'll be CTU and tiles (with adhesive, underfloor heating etc) but that is a LONG way off yet! Just need to get a floor to put it all on yet....

[weisyboy]

from the ground up it goes.

posts (sit in the ground), bearers (sit on the posts), joists (sit on teh bearers), floor (sits on the joists).

here is a pic of our floor

[TCX]

Hi Carl - thanks for that - with the help of some Google pictures I now get it! I was wondering how come I couldn't see that many stumps if each of the joists had one at each end. Funny how it is blimmin' obvious once you get it ! Well that makes things a lot better if I have to put new joists in - which I think I will in some cases - just fitting in a new horizontal piece, easy-peasy (see, I can do the practical bits, I just don't know what all the "bits" are called)!

OK, thanks to everyone for the words of wisdom! Fingers crossed for this weekend that all goes to plan (and none of the cats escape and fall down the hole!!)

Cheers,
T