SonataAdminBundle/Resources/config/templates.xml

<?xml version="1.0" encoding="UTF-8" ?>

<container xmlns="http://www.symfony-project.org/schema/dic/services"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="http://www.symfony-project.org/schema/dic/services http://www.symfony-project.org/schema/dic/services/services-1.0.xsd">

    <parameters>
        <parameter key="base_application.templates.layout">Sonata\BaseApplicationBundle::standard_layout.twig</parameter>
        <parameter key="base_application.templates.ajax">Sonata\BaseApplicationBundle::ajax_layout.twig</parameter>
    </parameters>

</container>