I have been reading some of the threads on insulating the front tack area.

What does double lined at the factory mean?  If the front tack/dressing room is "double lined," and if this does not mean it's insulated, how hard is it to insulate?  Would it be better to start without extra lining so insulating would be easier to start? 

What is considered normal factory installed insulation material (or what is the factory installed insulation in your trailer)?

The trailers I'm looking at both have insulated horse areas.  The new one has double lined front tack/dressing room walls, carpeted flooring, but nothing extra on the ceiling or end of the nose area.  The older one has carpted flooring only.

Thank you.