Sorry, I meant 'application'. My bad.
Good move; frames have been pretty much discredited and redundant for some years now. They're not particularity SEO-friendly (Search Engine Optimisation) and can be a pain to deal with any way. however, occasional use of
iFrames can be justified, IMO.
Do you have full access to your site via FTP, or are you using an online site builder? Is your domain PHP enabled?
The reason I ask is it may be worth considering the use of basic tables for layout and 'PHP includes' for global elements such as navigation, headers, footers.
This means, for instance with a side-bar navigation tree, you create one set of navigation links (saved separately as an HTML file), insert that file into a table cell at the side of the page using a simple PHP command. The sites pages would have to be saved with the .PHP extension, but otherwise you would treat them the same as HTML pages where coding/design, layout, content are concerned.
Doing this means you only need to change one file (the navigation HTML file in the above example) for all the instances of that navigation to be updated globally.
Just a thought.