The interior of the carport is actually 13' ish because the roof overhangs to make it a total of 15'. Overall a nice sturdy carport. Make sure when you order and pick up or have delivered you have a total of 3 boxes. We will see how this holds up in the winter.

Common problem should be fixed by manufacturer. I had 2 professionals put this carport together and it took them over 4 hours because of a common problem that has been expressed repeatedly in the reviews. The roof panels do not line up correctly and require 3/4 of the time to assemble. First off you will receive the unit in 3 small boxes {3'x2'} that will leave you thinking "this can't be all". The skeleton took my 2 professionals about 45 minutes to complete. The roof took over 3 hours because panels do not line up correctly and you don't notice the gradual gap until you believe you are almost finished. My suggestion is to simply leave a crooked gap and finish the roof so you don't have to redo the panels and cause more holes in the panels {roof} that will leave your carport leaking like a sieve. I wish my guys had told me about the challenge instead of disassembling it and making it square. The caulking is a mess, the additional holes cause it to leak and it simply looks terrible with the previous placed caulking around the new panels that are straight and square now. It would have looked a little lopsided but it would look better and not leak. Now I have to find someway to plug up all the holes and scrape the caulking off from the panels on the outside. The manufacturer should number/label each panel and include some way to keep every skeleton frame piece properly spaced so this challenge doesn't happen. Because of this I am not happy at all with my purchase.