Looks like a suitable case for a Shell Component. You can create one that is going to shell the whole area of your App. In this you can have a <router-outlet></router-outlet> which is going to host all the pages without the side-nav.
And for the pages that you want to have a side-nav, you can create a parent route(say /app) and then in its children define the routes for the pages that you want to have the side-nav.
So your routeConfig would look something like:
const APP_ROUTES: Routes = [
  { path: '6', component: Component6 },
  { path: '7', component: Component7 },
  { path: '8', component: Component8 },
  { path: 'app', component: ComponentApp, children: [
    { path: '1', component: Component1 },
    { path: '2', component: Component2 },
    { path: '3', component: Component3 },
    { path: '4', component: Component4 },
    { path: '5', component: Component5 },
    { path: '9', component: Component9 },
    { path: '10', component: Component10 },
  ]}
];
Now, in the AppComponent's template, add a <router-outlet></router-outlet>. This is supposed to load ComponentApp, Component6, Component7, and Component8. And then there would be ComponentApp that will have the side-nav and below that, another <router-outlet></router-outlet> that is going to load Component1-Component5, Component9 and Component10.
Just one thing that is going to be an issue in your case would be, you'll have to consider the children components to be under a sub-route.
Deborah Kurata has a very interesting NGCONF Talk about this and several other router related concepts that I suggest you watch to get a better understanding.