Extra ribs for fat teardrops?

[will guthrie]

I'm building the widget from plans that Andrew provided in the plans section of this forum. The plans don't show them but I was wondering if I should add ribs between the spars since the walls are about 68 inches apart. I'm a little concerned that the top skin will sag a little without added blocking. Has anyone run into this building a fat teardrop? I have the inside skin and spars on and am ready to insulate and skin the outside (pictures of this in my album). I wrote about this in a previously but it was buried in a long post and I didn't get any replies to this specifically but I'm sure someone out there has encountered this. Pardon me yall for being repetitive

[mikeschn]

Will,

I added center ribs on my Baja Benroy, which was 72" wide.

http://www.mikenchell.com/Baja_Benroy_P ... pic69.html

When I was done I could stand or sit on top without a problem.

Mike...

[Joanne]

And I thought I overbuilt....

Joanne

Will,

I added center ribs on my Baja Benroy, which was 72" wide.

http://www.mikenchell.com/Baja_Benroy_P ... pic69.html

When I was done I could stand or sit on top without a problem.

Mike...

[48Rob]

Hello Will,


Adding supports between the spars or ribs is a sound building practice.

It is especially important if you have a break in the sheathing, such as a roof vent, as it spreads the roof load from one, to several supports.

If you feel the roof skin, or sheathing may "sag" without adding center supports, the spacing between the side to side roof supports may be too wide?

Rob

If I had not added a couple extra supports, to connect the side to side roof framing, standing on only one of the supports would have caused too much deflection for my comfort... with the extra support provided by connecting the framing, I can easily walk on the roof without concern.
The roof supports are 3/4" x 2" Oak, pretty strong, but the tear is 7' wide.

<img src="http://img.photobucket.com/albums/v284/1948rob/Cabin%20car%20project/mirror2.jpg">

[will guthrie]

Thanks for the replies. I figured it was probably a good idea to add at least one center rib connecting the spars so I think I'll go ahead and do it. That sure is a beautiful interior Rob. Very nice work. Cheers