Often times when you create a new top level site collection you want to use an existing custom site collection. This can easily be done from the new site collection.
First, create the site template from the current site that you are using that you would like to reuse as a template. Note: If you do not see the option to save the site as a template, this means that various features are activated that don’t support saving the site as a template. You would need to deactivate these features and try again.
Enter the needed information and select ok:
A message will be displayed informing you that your template has been saved to the gallery.
Click the link provided to access the solutions gallery. When the gallery loads, click on the name of the template you created and when prompted choose to save the file to a location you can reference later. (We will need to access this location when we use the template on our new site collection)
Now, when you create the new site collection in Central Admin, select the custom template called “Select Template Later…”. (If you have to request a site collection from another resource, be sure to specify that you want to use this template).
When you try first access the new site collection you will be directed to the template picker page. You will see all the available templates, as well as a link to the Solution Gallery. You will want to click on the solution gallery link.
Now we will need to upload our template we created above to the solution gallery. Once we upload and activate the file we will be able to select it as our template for the site collection.
When the solution is uploaded, you will see a dialog where you can activate the solution. Activating the solution will make it available as a site template.
Now, use the breadcrumbs to go back to the home page.
You should now see your template under the custom tab for site templates.