I guess the longarming question is the most critical for you. Otherwise, I do seams either or both on my backs. Whatever way the piece of fabric I have fits the best in relation to the top.

I am piecing a backing now...LOTS Of seams! lol Here is a quick pieced back..cute and one of my favorites:

http://www.maryquilts.com/off-center-4-patch-backing/

Be sure to look around, she has lots of patterns.

My guild has many guests speakers and their quilts have pieced backing a lot. Some even put ophan blocks on the back. You can do it however you want.

I like this Diagonal Backing Calculator method. :)

I longarm quilt for others and it does not matter to ME which way YOU PIECE your quilt back or how many pieces you use.

What's important is that you use 1/2" seams (NOT 1/4"...it's too skimpy). Put smaller pieces in the center of the quilt back...not at the edges. If you put them along the edge, there is the possibility that only a small amount of the smaller piece will end up on the back.

What's important, if you're sending the quilt to a longarm quilter, is that the back is large enough, square and flat. I've done many, many quilts with pieced backs and several quilts that were actually two sided quilts. The quilt tops are centered on the quilt back.

Nan - Indiana

[QUOTE=terlyn;6621302]I've learned so much from the questions ive posted here before.
Now...I cannot find any 108" wide backing fabric to match so I will have to piece tieback.
Do I make my joining seam vertically down the back or the seam across horizontally?
Terry[/QUOT

I was told years ago not to have a seam in the middle - it's where we generally fold them and it weakens over time. If I am joining two pieces of fabric, I cut one length in half and join on both ends - no middle seam. I think backs are fair game, no rules really, just add where you can and avoid the middle seam.

The quilt does not care which way you piece the back.It all depends on how big your quilt is. I usually piece the backing vertically because it seems to take less fabric. Most of my quilts are 75x90 so I piece 3 yds vertically which gives me a piece of backing 90 x 108. I usually rip my salvages off and have the fabric cut into 2- 3yd pieces. I pieced a backing fabric once from leftover pieces of fabric and never again. What a pain!!! Also by using one color backing you do have to worry centering it on the toip.

Figure the yardage and decide which way will take the least fabric. It can be eye opening for some quilts.

For me it depends on how much fabric I have, the size of the quilt and whether the fabric for the backing directional. I do whichever way works given those parameters and don't worry about whether it's vertical or horizontal. I do my own quilting however so had never thought about which is better for a long arm. Good tip there.

Because I longarm, I always join the seams horizontally.