raising existing joists

[ash91]

hi, I need to pack up some existing ceiling joists by 4" to meet with existing floor level on 1st floor.
What is the best way of fixing 4x2 onto the 8x2s? Long screws straight down or can they just be toe nailed In place? Also would you run the 4x2 at 90 degrees to the existing joists or parallel? Cheers

 

[Jackrae]

If you run at right angles you end up with a much stronger and more stable structure and 150mm decking screws, into 15mm recessed holes, will hold things in place.

If you have finished ceilings below the last thing you want to be doing is banging nails into joists.

 

[big-all]

trouble with alternating and cross fixing if you are using visible planking it will be at right angles

 

[ladylola]

trouble with alternating and cross fixing if you are using visible planking it will be at right angles

Exactly what I was thinking in which case they probably would need placing directly on top of the existing joists. To do that I'd screw plywood cheeks to the sides of both timbers and fit noggins for added ridgity .

 

[Jackrae]

One of the problems of fixing on top of existing joists is that any distortion, twisting or humping of the joists will get amplified by the additional pieces.
The OP only asks for a level floor and does not specify he wants to run finished boards through into other rooms. In many (older) houses it is quite common for joists and flooring to be at right angles between different rooms with the transition taking place under the room door thresholds (which current nanny state seems to have objections to)

 

[ladylola]

Yes very true , I suppose big-all and myself were thinking worst case type of thing. I agree that running at 90* is the best idea. Perhaps a little more info in the original question would have helped , no offence ash91 .
Actually thinking about it I would be interested to know why these two floors are different heights in the first place.

 

[ash91]

Hi the reason the floor is not at the correct height is because the original extension was not set out correctly, now a 2nd storey has been added it now needs sorting, the floor will meet at a doorway and will be chipboard then carpet, so nothing visible. Any more information needed?

Thanks

 

[ladylola]

No not really. 90* it is then . I've fixed joists like that and have skew fixed and as belt and braces fixed a 2x2 ( and also on another occasion metal angle) vertically at the intersections tying both timbers together.