Web site usability is an essential element in a web site; nonetheless, one can find an abundance of web pages with poor usability. This discrepancy is the result of limitations that are currently preventing web developers in the commercial sector from producing usable web sites. This work proposes a framework whose objective is to alleviate this problem by automating certain aspects of the usability evaluation process. Mainstreaming comes as a result of automation, therefore enabling non-expert in the field of usability to conduct the evaluation. This results in a reduction of the costs associated with such an evaluation, whilst overcoming other limitations such as the need to engage usability experts and inconsistent evaluations. Additionally, the framework allows the flexibility of adding, modifying or deleting guidelines without altering the code that references them. A comparison of the evaluation results carried out using the framework against published evaluations of web sites carried out by web site usability experts reveals very encouraging results.