45x70 or horizontal 45x145?

[abel48]

Which will be stiffer, a 45x70 or a horizontal 45x145? It will have flooring chipboard on top.

Best regards, Anders

 

[Rabbithole]

A little more detailed explanation of what you plan to do. And preferably a picture that describes the situation would help to brainstorm a good solution.

Do I guess correctly that you plan to lay out:
Option 1: Height 70, width 45
Option 2: Height 45, width 145

 

[Kallebo]

Purely mathematically, standing 70x45 would become marginally stiffer. In reality, you have more opportunities to fasten the 145s, and the impact from deformations becomes smaller.

There is quite a significant price difference between the alternatives as well.

 

[richardtenggren]

You could go up to 45x170 to get less deflection, but it is more efficient with a cross-section that is taller than it is wide, as the height has a greater effect.

 

[abel48]

To be used as studs across the logs here that are placed at cc80-cc100
Attached image

 

[Slarvpellen]

45x70 is probably borderline with a bit too much deflection in places, I *guess*.
Wouldn't you consider placing the battens parallel on top of the logs?
Alternatively, you could consider 45x95, which is likely stiff enough, and notch for the logs so it builds less in height.
You can also consider whether to set cc-60 or cc-30; there are different ways to achieve stiffness and leveling without having to build too much in height.

 

[abel48]

The initial idea was to align parallel with the logs, but they are round on the sides, so it becomes cumbersome. I believe 45x95 will be too high... but it should work with 45x70 on cc45 instead of cc60?

 

[Finndjävel]

45x70 will probably be good for that purpose. There will be no deflection.

 

[Rabbithole]

You can certainly install double screw-glued floor chipboards too if you want to reduce the building height