Which user permissions to check before writing files to disk?

[simurq]

I've made an Excel add-in that's supposed to write its own settings folder and file to user's APPDATA folder under Windows 7+. What will be the preferred method to check permissions (folder or user? confused...) before saving data to that folder?
Currently I use a simple line of code below but am also thinking of ICALCS, but the problem is at add-in's initialisation stage, I don't want to use shell scripting library before library associations checks are complete. So, smth that uses VBE built-in functions is welcome:

[COLOR=green]'Proceed if the folder is NOT read-only
[/COLOR][COLOR=darkblue]    If[/COLOR] (GetAttr(Interaction.Environ("APPDATA")) And vbReadOnly) = 1 [COLOR=darkblue]Then[/COLOR]
        ReadOnly = [COLOR=darkblue]True[/COLOR]
        [COLOR=darkblue]Exit[/COLOR] [COLOR=darkblue]Sub[/COLOR]
    [COLOR=darkblue]End[/COLOR] [COLOR=darkblue]If[/COLOR]

Thanks!