Column width not working in DataTables bootstrap

Question

I am using the following code to set the column width of a DataTable. During partial page load the width appears to be correct and when it loads completely, the width is off.

<script>
    $(document).ready(function () {
        $("#memberGrid").dataTable({
            "dom": 'T<"clear">lfrtip',
            "tableTools": {
                "sSwfPath": "../../Content/swf/copy_csv_xls.swf"
            },
            "destroy": true,
            "info": true,
            "bLengthChange": false,
            "bFilter": false,
            "bAutoWidth": false,
            "aoColumns": [{ "sWidth": "20%" }, { "sWidth": "20%" }, { "sWidth": "20%" }, { "sWidth": "10%" }, { "sWidth": "20%" }, { "sWidth": "10%" }]
        });
    });
</script>

Table Markup

<table class="group-grid table table-hover table-bordered table-responsive zebra-striped" id="memberGrid">
                <thead class="tablehead">
                    <tr>
                        <th style="width: 20%">Name</th>
                        <th style="width: 20%">Room with</th>
                        <th style="width: 20%">Extensions</th>
                        <th style="width: 10%">Travel Protection</th>
                        <th style="width: 20%">Flying from</th>
                        <th style="width: 10%">Balance</th>
                    </tr>
                </thead>
                <tbody>
            <tr class="tablerows">
                <td style="width: 20%"><%# Eval("Travelers") %></td>
                <td style="width: 20%"><%# Eval("RoomMates")%></td>
                <td style="width: 20%"><%# Eval("Extensions")%></td>
                <td style="width: 10%"><%# (string) Eval("HasTpp") == "Y"? "Yes" : "No"%></td>
                <td style="width: 20%"><%# Eval("Airport")%></td>
                <td style="width: 10%">$<%# Eval("Balance")%></td>
            </tr>
            </tbody>
                    </table>

Answer 1

When setting columns widths, you also need to set:

autoWidth: false

...on the DataTable itself

Answer 2

Would be nice to see your table in action, but I get a strong feeling that this is a pure matter of width of content. Elements with display: table-cell will try to expand in order to show as much as its content as possible without wrapping. For example, the width of the <th> that has the caption "Travel Protection", which you define as 10% - you would need a rather broad table to show "Travel Protection" within 10%.

So overrule the default word-wrap and word-break settings for <th> like this :

table.dataTable thead tr th {
    word-wrap: break-word;
    word-break: break-all;
}

a sort of demo (as said, cannot proof this to your table IRL) -> http://jsfiddle.net/9vbz7thp/

The best thing would be to adjust the content of the <th>'s so they fits to the hardcoded widths.

If it is the content of the <td>'s that grows too large (typically a loooong not breakable word) :

table.dataTable tbody tr td {
    word-wrap: break-word;
    word-break: break-all;
}

BTW: You do not need to define hardcoded widths in both <th> and <td>'s. <td>'s automatically get the width from the corresponding <th>.