The nailers chosen for the interior oak headliner were 2" x 3".  This size coordinates with the roof spars.  As stated previously, this size is being used to accommodate a larger R-factor insulation.  Also, it provides a wider surface to better attach the inner headliner and outer  panels for supporting the aluminum skin which will be applied  soon during construction.  In order to follow the curved surface with the nailers,  I transferred the curved dimensions to  2" x 4"  stock by clamping the stock to the outside of the trailer and tracing the outline onto the 2" x 4" sections.  They were then cut out with a band saw.  A saber or jig saw would suffice. The nailers were then glued and screwed , then sanded to conform to the edge surfaces of the plywood.

The headliner is Oak from three (3) sheets @ 1/8" x 4' x 8' . The sheets are Luan on one side. as seen in an outside photo below, and are used primarily in the construction of interior doors.  These sheets are also available in Birch and other fine woods.  They were not available at any of the Local Home Depot stores , and were purchased at N.A. Mann lumber in Canton, Mi..  The cost for Oak per sheet in 2000 was $30.00, versus $15.00 for Luan on both sides. In order to lower the project cost factor, paneling could be used as a  substitute.  Since the headliner was already four (4) feet in width, it fit up to the 16" centers of the roof bows.  I measured from an end, and cut each panel at 55", the width of the roof bows and interior.  The remaining 41" x 48" sections will be used for the sides.  

As stated earlier, the roof spars are from 2" x 3" pine.   To provide additional support for the pine spars, I joined them with L brackets to the 2" x 3" nailers.  The vent is a standard 14".  The cost in 2000 was $20.00 and can be had at most any RV outlet.  The tinted lid was our choice.  They are very simple to install. It is just a matter of building a simple support frame.  If you prefer, use the template that is provided with the vent.

Before installing the Luan panels on the outside to provide a support surface for the aluminum skin, I must finish routing all wiring.  After wiring, I have decided to use R-11 insulation between the roof spars.  The correct thickness for the roof spars is 2 1/2", and the standard R-11 insulation is 3 1/2".  This means I will have to compress the additional 1" thickness, and thereby decrease the R-factor.

I found that working with this 1/8" thick panel is very easy.  The major strength is at the center of the curves. Make sure you apply a generous bead of Liquid Nails on the underside of the roof bows,. If you work alone, then I suggest that you secure small wooden blocks to the inside of the plywood sides near the top.  This will act as a guide, and assist in panel placement  while you are pounding in the #17-1" wire nails while the adhesive is drying.  If you have someone that can assist, then the job is really very easy.  At $30.00 per sheet, make sure that your measurements are accurate!