Assuming you're using the default magento layout-
Open app/design/frontend/default/default/layout/catalogsearch.xml
< catalogsearch_result_index translate="label" > < reference name="root" > < action method="setTemplate" >< template >page/1column.phtml< /template >< /action > < / reference > </ catalogsearch_result_index>
Since you are not using Layer left block this will solve your issue.