Moisture barrier

I am turning a barn (carriage house) into a guest house.  But I very concerned about moisture/leaks. The barn currently has only 5" lap siding over the 24"o.c. studs.

Without removing the siding, how can I create an effective moisture barrier and add insulation before I put up the

gyp board?

Thanks for any help you can offer.

Robert

Robert,

The product I would recommend is called icynene insulation.  We have used it in situations such as vaulted ceilings.  It does not require any type of vapor barrier since it is air tight and it provides for maximum R value.  You can do a google search for more information on it.  It is a spray on type that requires professional installation.