I am going to make a post that will need to support quite a lot of weight, say between one and two tons. The post is not the only support point, but it will take a large part of the weight from a roof.
I have some pieces of 2"6 k12 lumber that I plan to put together into a 6"6 post using a couple of wood screws. I thought that if you place two whole boards on the outside and leave several pieces with gaps in the middle layer, maybe the post will be more resistant to load that comes at a slight angle. Does anyone believe in this idea, or should I put together three whole boards?
I have some pieces of 2"6 k12 lumber that I plan to put together into a 6"6 post using a couple of wood screws. I thought that if you place two whole boards on the outside and leave several pieces with gaps in the middle layer, maybe the post will be more resistant to load that comes at a slight angle. Does anyone believe in this idea, or should I put together three whole boards?
Spacing does not increase strength.
It saves on timber without significantly reducing strength in one direction, but significantly reduces strength in the other.
Not recommended if you're looking to maximize load-bearing capacity.
It saves on timber without significantly reducing strength in one direction, but significantly reduces strength in the other.
Not recommended if you're looking to maximize load-bearing capacity.
Depending on how long the pole is, buckling rather than compression is the most critical factor, and then the construction of the column can make a big difference. The resistance to bending can change dramatically depending on the geometry of the pole.
However, it is the moment of inertia and the radius of gyration that are used to design columns. Although closely related to bending resistance, they are not entirely the same.Gabbe1 said:
Well, a 2"x2" should handle at least that weight, as a theoretical strength of spruce/pine. I’m not sure what safety margin a designer would apply.
But it's buckling that it can't withstand. So it's wise to join some beams together. And the resulting buckling resistance is better the larger the cross-section the post forms (with or without cavity).
I think you're good (although I don't know your unsupported buckling length!) with 2"x6" according to ...:
2 joined together to make a 4"x6"
3 joined together to make a 6"x6"
2 joined with a 2x3" between, so the profile looks like an H with an outer cross-section of 6x6"
4 joined, long side to short side, around the whole way so the resulting post becomes an 8x8" with a 4x4" hole in the middle.
In any case, keep in mind the moisture, e.g., 3 screwed together have the tendency to quickly draw in water capillarily in the gap, but then dry quite slowly.
But it's buckling that it can't withstand. So it's wise to join some beams together. And the resulting buckling resistance is better the larger the cross-section the post forms (with or without cavity).
I think you're good (although I don't know your unsupported buckling length!) with 2"x6" according to ...:
2 joined together to make a 4"x6"
3 joined together to make a 6"x6"
2 joined with a 2x3" between, so the profile looks like an H with an outer cross-section of 6x6"
4 joined, long side to short side, around the whole way so the resulting post becomes an 8x8" with a 4x4" hole in the middle.
In any case, keep in mind the moisture, e.g., 3 screwed together have the tendency to quickly draw in water capillarily in the gap, but then dry quite slowly.