Different joist centers

[Sonyman]

I have just ripped out my old kitchen and floor to level al the joists, and found that 3 were rotten, and 2 had big sections cut out of the at the top near one end. Also all the joists were of 2 different sizes, as in some were 4x2 and the rest were 5x2.
I have replaced the 3 rotten and 2 cut out ones with 5x2 or 47mm x 122mm.

I have found when putting the joists back in, that the centres are all different!
Some are 360mm at one end and 330mm at the other, while the ones (2) I have put in are at 385mm. I was trying to get them as close to 400mm as possible without chopping out more brickwork from the pockets, but then found that none of the ones left in are anywhere near 400mm centres.

I am putting down 1220x2440x25mm DWP on top of the joists, and also found that the 1220mm measurment does not come onto any joist, so I will have to cut each board to suit my joist centres, unless ther is another way round it.

Thanks

 

[noseall]

measure where the end of the board will fall. in your case between joists. fix a noggin at each end of the gap so it bridges the gap joist at each end. then fix another length of 5"x 2" down the length, between the noggins and on line with the plywood end.

i do hope this makes sense!

 

[Sonyman]

Thanks for the reply and yes it does make sense after I read it a couple of times.
I am not sure it would be practically easy to do that because if I read it correctly, the noggings would have to fit as close to the ends of the joists as possible so as to get another joist fitted inbetween them for as long a length as possible.