simple framing question

mrmac204 · 06-16-2008, 12:11 AM

Ok, I'm not a framer! so of course I had to build a shelf over top a garage door, 6' x 12' - (my fiance's place, so I didn't get paid LOL) anyhow, I laid it all out, 16" centers etc. put in a pressure block, then a joist (2x4) all the way to the end, putting in a pressure block every other joist, then went back and put in the rest of them.
Now comes time to put the plywood on, but it doesn't fit! plywood is 8' (I checked) so that means that my framing is wrong! damn!
I am not sure but I think I might have screwed it up with the first pressure block - it was 14 1/2" long (all of them are) my plywood was almost exactly 3/4" too short- it came to the inside edge of the 8' joist. I ended up just moving the plywood over 3/4" inch - not a great fix, but its sound, and its a shelf. I know, excuses suck.

so I know I screwed up the layout. Is it at the first (second?) joist? should the pressure block in that location have been 3/4" shorter? or something else?

thanks

Mac.

buletbob · 06-16-2008, 06:21 AM

When you layout for 16" oc your first measurement will be 15 -1/4" Make a line and put your X to the right then from that line start marking 16" oc then when you lay down your plywood it will fall on the center half of your framing. another way is to lay your ruler down 3/4" past your start point and then start marking out for your 16" oc . good luck BOB

**AtlanticWBConst.** · 06-16-2008, 06:41 AM

I'm trying to follow your description of what you did, and what the problem was.

I think this is the gist of your post: You built a storage shelf system in a garage. It is approximately 6' wide, by 12' long. You installed the shelf's joists at 16" On Center.
However, when you laid your first sheet of plywood, it did not fall properly on the joist that is at the end of the 8' plwood sheet.

If that is the case, then this is my response: You should have measured 16 -3/4" off the first end joist (rim joist), to mark the location of the next joist's center.

Example: If you laid your 4x8 sheet of plywood onto a floor, you want the end of the plywood to be able to seat 1/2 way on the last 2x4 joist, so that you can lay your next sheet of plywood, onto the other half of that 2x4 joist. If your sheet of pywood is 96" long, then that end 2x4 joist's center, should be at 96 -3/4".

So, you had your starting joist (rim joist) set in place, your first O.C. mark (for the next joist) should have been at 16-3/4". Then you would pull all you consecutive joists centers off that one. Thus, your 16" increments land at the halfway mark of each 2x4 joist.

mrmac204 · 06-16-2008, 08:11 AM

ok, thanks guys- that makes sense now. because it was the rim joist, and the plywood was starting at the outer edge and not the center of the rim joist, I should have made the first joist in 3/4" less than 16 inch oc. Doh!

a learning curve! I won't make that mistake again! honest!

thanks again

Mac.

buletbob · 06-16-2008, 05:10 PM

Correct . that is where you get the 15-1/4" from
then all you have to do is mark a straight line and put your X or slash mark to the right so you know which side the framing member rests. the straight line represents the left side of the timber and helps buy giving you a guide to keep them straight,
My old man taught me 42 years ago to leave your ruler 3/4 " hanging over your starting point and mark out your 16" oc that way. back then we all had wooden Luken folding stick rulers, today there all tapes a lot quicker. now i mark 15-1/4 mark set a nail on the mark and pull 16's that way. which ever works for you.
Either post will get you where you have to be.

bigbavarian · 07-08-2008, 04:39 PM

Mac,

We all begin somewhere. I learned that when refinishing a wall in the basement. Drilled and screwed furring strips in along a long wall. Then when I went to put the first piece of drywall it was off.

It took me a while to figure out what I did wrong.

Lot of hard work for nothing.

Learn as you burn.

Stephen