Here are a bunch of notes on window replacement from various sites.
[1.] Notes on working with Lexan, from Spartan trailer forum: (source: http://www.spartantrailer.com/)
Lexan, is easy to work with! You will need a lexan cutter ( were you get
your lexan) straightedge W/ a couple of clamps! Set up your clamps and
straightedge at the size of your window( make sure this is clamped well) and
useing your lexan cutter pulling lightly to you along the straightedge ! This
will sound like fingernails on a chaulk board, increasing pressure with each
pass! The idea is to make a score or cut 1/4 the way through! Then with the
cut along the edge of the work surface,(With the cut up) push down to break
allong the cut! The more you score or cut the lexan the easier it is to break
along this score or cut!
Take your time, measure twice, score more than think,keep score at the edge of
work surface,start at one end and push down starting your break working down thscore! You can get a small pieace of plexiglass to pratice with ! Good luck from Al freitas 52 53 Royal Spartanette
- Removing the old windows was a fairly easy task. The original windows were held in by a gasket sandwiched between the outer shell and an interior strip of extruded aluminum, which was screwed into the trailer frame. This photo shows the right front window removed and the aluminum cleaned to accept the new window. I used large sheets of heavy paper to create templates for the new windows to be cut from. The old window were used as patterns. Some adjustments were required in order to get an optimal fit. 3/16 inch Plexiglas was used for replacements at a cost of about $150. This included them being cut to my templates.
 The new Plexiglas is in place. It is amazing how fresh the new windows make the trailer appear. It is nice to be able to have a clean view from this great picture window and the best part is there are no more water leaks! After almost 3 years the windows seem to be doing great. The plexi is exposed to full sun and has not discolored and the seals are still tight.
Instead of using a gasket for the window replacement I opted to use a newer product Dow Corning #795. This is an industrial grade glazing material. This close up shows the new window set in the sealant and shimmed with penny’s. The excess sealant was cleaned off with mineral spirits.
This close up shows the new window set in the sealant and shimmed with penny’s. The excess sealant was cleaned off with mineral spirits The new Plexiglas is in place. It is amazing how fresh the new windows make the trailer appear. It is nice to be able to have a clean view from this great picture window and the best part is there are no more water leaks! After almost 3 years the windows seem to be doing great. The plexi is exposed to full sun and has not discolored and the seals are still tight.
[4.] replacing window frames on a Sovereign trailer: http://sweetsovereign.blogspot.com/2005/12/windows-windows-and-more-windows.html
Replacing the Roof Vent
The roof vent covers have a nasty tendency to depart Airstream roofs. It is too bad, as the early covers are works of art by Hehr – solid aluminum, 3 piece with a built in rubber seal. The Hehr logo script was embossed on the underside. They are no longer available, except from owners who have changed their vent openings over to Fantastic Fan conversions or Air Conditioners. Generic replacement covers are sold at RV stores, but need modification in order to work.
This topic covers the modifications required to use a modern generic cover, and how the vent housing assembly was reinstalled after the removal of a roof mounted A/C. This will also give you an idea of how other such skin mounted fixtures are installed.
The original vent is unique in that it is a 12×12 opening with a 14×14 pan lid with a captivated rubber seal that drops down onto the top of the opening, creating the closure seal. The modern replacements are a true 14×14 that are designed to drop around an opening. This results in no sealing action if used as is. The lip of the opening has to be built up and out for it to work. This style vent made by Hehr was used until about 1966, at which time a vent made by Hammond was used. Modern Lexan replacement covers from RV places are about the only replacement available at this time..
1- Here is the vent/fan assembly on the bench prior to installation. You can see the hinge fittings to either side that attach to the cover with 3 holes.