Previously i have a post about using Bootstrap 3 theme in Drupal 7.

• Drupal 7 – Setup Bootstrap 3 Theme with Gulp for LESS compilation

If the website you are building needs IE 8 support, a few hacks has to been done. Please note that using CDN to serve the Bootstrap source files will not work in this case. So you have to use method 1 to serve the Bootstrap source files locally when installing the Bootstrap 3 theme in Drupal as stated here.

1. Copy the system/html.tpl.php from the Bootstrap 3 base theme to your subtheme templates folder.

2. Replace the

  <!-- HTML5 element support for IE6-8 -->
  <!--[if lt IE 9]>
    <script src="//html5shiv.googlecode.com/svn/trunk/html5.js"></script>
  <![endif]-->

To:

  <!-- HTML5 element support for IE6-8 -->
  <!--[if lt IE 9]>
    <script src="/sites/all/themes/street/bootstrap/assets/js/html5shiv.min.js"></script>
    <script src="/sites/all/themes/street/bootstrap/assets/js/respond.min.js"></script>
  <![endif]-->

3. Add the following meta

<meta http-equiv="X-UA-Compatible" content="IE=edge">

Done =)

Reference: Drupal Bootstrap – Document internet explorer support