Sunbrella fabric is the fabric of choice for marine canvas work. Sunbrella material will standup to the sun/UV for at least 10 years which far exceeds any other material available for a comparable price.
As mentioned earlier,the thread used to stitch the material together will fail before the fabric will. In that regard, bonded polyester thread size V-92 will far outlast any other thread except for the Gore tex Tenara thread.
Typically, in Southern California, polyester thread will require re-stitching in about 7 years. This isn''t that big of a job in reality. If you have enough skill to do the sewing to create the article initially, re-sewing the seams is really quite easy.
When the thread requires re-stitching, only the thread exposed to the sun is affected. Most seams have an additional stitch that is actually hidden from the sun. It is usually still in good condition and will hold the seam together until the exposed thread can be re-stitched.
Gore tex thread was recommended earlier as it will not rot in the sun which is correct. However it is considerably more expensive than the standard polyester bonded thread. 1850 yds of Gore tex thread costs $150....as opposed to about $20 for the same quantity of polyester thread. I''m willing to do a lot of re-stitching for the difference!
You should read a couple of books on the subject of canvas work before getting into the actual work. You will find it time well spent.
Suggest you read The Complete Canvas Workers Guide by Jim Grant, and/or Canvas Work & Sail Repair
by Don Casey.
Hope this helps,