Should I be concerned about my new "6x6" posts that are not really that size?

Question

I'm replacing my 200 sq ft 2nd-storey deck which is held up by the side of the house and two 6x6x18 posts. I special-ordered the new posts from Home Depot, installed the first one, and unfortunately found the new one to be slightly smaller. Actual measurement of the old post (non pressure treated) is 5 3/4" on its side, while the new one (pressure treated) is 5 3/8". HD maintains what I got is standard for a 6x6.

Will the 3/8" smaller dimension of the new posts put too much pressure on them, and hence make them buckle? A quick estimate seems the lbs/ sq in. pressure on them will increase 14%.

Should I be concerned....and try find a real 6x6 post, or put a 3rd post in? Thanks in advance for your advice.

Answer 1

Really can not answer the question without knowing the weight each post is carrying.

New lumber is small today because of cost cutting by company.

I say it should be OK, but if if would make you feel better, add another post or use a 4" metal tubing or pipe column.

Answer 2

It is not a big deal - this is the *nominal dimension.

What concerns me more is that you brace the posts midway until the treated posts dry out a little. This long of a post is subject to twisting and bowing as it dries out.

Answer 3

2x4s are not 2x4s nothing made today is what the specs say  if the 14% reduction bothers you put up the 3rd post

Answer 4

2x4, 6x6 etc is the pre-planed size. I'm assuming these weren't rough cut. HD is correct on the size, though they should have explained this to you.

Answer 5

that's standard cut it will handle the weight the same-make sure no rot knots or splits in wood

Answer 6

How far apart are the post? Just as important as the post is the beam. Just be sure the beam that you nail the joists into is a doubled 2x10. It's a good idea to have a post at least every 8 ft with a doubled 2x10. You could maybe triple it to span a little further. And of coarse use joist hangers. As far as the size of the posts goes, you should be fine in the strength department. The main concern with a post that long is twisting or bowing. The 14% reduction isn't as much of a factor as the grain of the wood or the location and size of the knots. The more exposed to the sun they are, the more likely they are to twist. Hopefully on a special order they pick really nice clean straight boards for you. Good luck!

Answer 7

The actual measurement's have gotten a tiny bit smaller over time but a 6x6 is NOT 6x6 it is just a tiny bit over 5 inches, the 3/8's sounds right. You should measure a 2x4 if you want to be confused!

If you really want something to be 6x6 you have to order 8x8's and cut them down or go to a saw mill and have them cut for you.

In any case if the difference you noted makes a difference, the 6x6 is not large enough in any case.