Stand Construction - Post Spacing Question

[Anonymous]

Hey, I'm not a carpenter.

So you really think I should put some beams across the whole thing on the top, then put the plywood on top of the beams?

I thought the posts were carrying the weight and that the plywood would spread the load. As long as the post are adequately braced, they can't move from side to side, and therefore the stand would be rigidly built, no?

louey

Double 2x4 headers are commonly used on 16" centers. The outside is sheathed in plywood and that is where the real strength comes in as it keeps the 2X4(posts) from deflecting and it also supports the 16" span with the double 2x4' on top of the wall. The same thing happens at the bottom of the wall to spread the load over the existing floor without blocking or additional support. The only place you will need a beam is over your doors. You can span 12' of opening in a home using two 2x12 pieces for the beam. THe beam is supported by 2x4 posts at each end. For a 2' door opening you should be ok with a double 2x6. You should also consider putting in cross pieces to support the top ever 16" or less to support the top plywood

Your putting your heavy lumber into posts and then not putting anything on top to stop flexing.

I am not sure what advice to give you at this point except that having big posts doesn't help if there is not a beam or wall to spread the load.

Several years ago, I built a shelf out of 2x6's. I formed a 4'x8' rectangle with the 2/6's standing on edge. Every 16" I put an additional 2x6 aross the 4' dimension. I screwed down a 3/4" peice of plywood to this frame and then put 2/4 legs under it at each corner and in the middle of the 8' side.

Onto this shelf or table I put a 90 corner, a 20 sump, three 40 gal prop tanks, an 30 gal. algae scrubber and a water change tank. I also got up on the stand at times to work on plumbing. It was very ridgid because of the framing under the playwood and not because it had huge legs.

 

[Anonymous]

If you don't use something on top of the posts, then the plywood is carrying all of the weight. Picture a canvas tent with poles holding it up. You have load points because the canvas isn't strong enough to span from post to post. So you give it a base. If you use two 2X4's flat, then the posts should be no further than 16" apart. If you set the two 2/4s up on edge you can easily span 24+ inches. If you use two 2/6's then you can go 4' or more. Cut the posts off enough to allow for more beam height. Then all you have to worry about is racking and the way you have it built into the two existing walls, there isn't much worry in that.

 

[Anonymous]

Would two sheets of plywood on top spread the load? How about three? I really don't want to cut the 4X4's down because my radial arm saw doesn't do 4X4's. And I really don't want the stand to be much taller.

Louey

 

[Anonymous]

Sure, use angle braces and put the supports between and evwn with the top of the posts. not quit as strong but the braces will help alot.

 

[Anonymous]

Hows' this look? Ready for two sheets of 3/4" plywood?

 

[Anonymous]

and another...

 

[Anonymous]

check your PM!