Load-bearing capacity of a plank floor?

[Verga]

I have joists at 1500 CC where I plan to lay a plank floor. How much load can a plank at 1500 CC withstand? The "floor" will be in the attic and will never be loaded by more than a crawling adult. What dimensions of timber can handle this, and what do you think is most cost-effective?

It doesn't matter if it flexes, but they must not break!

 

[justusandersson]

The most cost-effective option is probably to lay ordinary, 22 mm thick, raw wood planking. It will bend at most 2 mm when a full-grown person walks on it. Non-grooved wood will not be cheaper, and thinner dimensions will be perceived as unpleasant.

 

[Urban J A]

I myself have 22 mm råspont in an attic with 1200 between the rafters. You can notice that it flexes; without the råspont it would probably be unpleasant.

 

[Verga]

Thanks for the response, found a 23 x 120 råspont that I'll go with!

 

[Verga]

Can confirm that it turned out as stable as can be, at least for a wind

Thanks for the help!