How to SendRedirect outside a iFrame

Question

I have this structure:

<div id="head">
    <ui:insert name="cabecera"><ui:include src="header.xhtml"/></ui:insert>
</div>

<div id="menu">
    <ui:insert name="menu"><ui:include src="menu.xhtml"/></ui:insert>
</div>
<div id="contenedor">           
    <iframe id="frameCuerpo" src="init.xhtml" name="frameCuerpo" frameborder="0" scrolling="auto" />            
</div>  

<div id="footer">
    <ui:insert name="pie"><ui:include src="footer.xhtml"/></ui:insert>
</div>

To control sessions I have created this method to check if session is expired when I click on any menu item, if expired then redirect to the login page.

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
    
    HttpServletRequest req = (HttpServletRequest) request;
    HttpServletResponse res = (HttpServletResponse) response;
    HttpSession session = req.getSession(false);
    String loginURL = req.getContextPath() + "login.faces";

    boolean loggedIn = session != null && session.getAttribute("Username") != null;
    boolean loginRequest = loginURL.equals(req.getRequestURI());

    if (loggedIn || loginRequest) {
        chain.doFilter(request, response);
    } else {
        
        res.sendRedirect(loginURL);     
        
    }
}

The problem I have is that it is redirecting the login page into the iframe, no to the top of page.