I'm sorry, when it comes to Retro-Spin ™ roof flashing you'll have to ask a roofer.

If you mean retro*spring*, this webbed site we are on... does it have to be safe? You're putting in public data here, what is there to lose? You don't give this permission to send tweets or anything, like you'd do with other similar sites that shall remain unnamed.

That being said, you can look at the source code on github: https://github.com/Retrospring/retrospring. See if you find a problem with it!