Monday, February 24, 2020

Window installation procedure -Silpruf method

I've been working through the side and door windows using the Silpruf method I mentioned in my last post.  I really like how its turning out so I thought I would document the process in a little more detail in case I want to use this in the future.  If somebody else is reading this I highly recommend you watch the video's at least once and then feel free to use the checklist I created below.

First, you need a few items.

  • SCS2000 Silpruf in the color you prefer.  I used black and will probably use 2 tubes for all 5 windows.
  • Popsicle sticks.  I cut these into thirds to act as "slats" to help hold the window flush with the cabin top.
  • rubber gloves...lots of rubber gloves.
  • plastic squeegee.  Cut into about a 1" edge size.
  • dry erase markers.  Thin edge and best get a few.  I bought a 4 pack on Amazon.
  • Permatex Ultra black RTV (black because I was using black Silpruf)
  • 1/4" masking tape.  (couldn't find the link to what I purchased)


To Do Trim window with a 3/16" gap between edge of glass and recess wall
To Do Sand top edge of glass to form 1/16" rounded edge. 
To Do Sand edge of glass with 300 grit to make a defect free edge
To Do Drill cleco holes in recess to support window in opening.  Approximately every 4-5"
To Do Install window and mark inside edge surface of window where the recess wall ends (with erasable marker.)
To Do Remove window and place outside face down on a white towel.
To Do Apply 1 layer of tape about 1/8"-3/16" from inside edge of line just created.  This is done with 1" tape or larger.
To Do Apply first layer of 1/4" masking  tape such that it leaves the line  fully visible.
To Do Write a small number 2 on the top end of the tape.
To Do Wipe dry erase line off of window with damp cloth. 
To Do Apply second layer of 1/4" masking  tape such that it covers the outside edge of the first layer of 1/4" masking tape by about 1/16".  Mark the end of this tape with a number 1.
To Do Sand inside surface of the window where it will be glued to the frame.  This helps the Silpruf adhere.
To Do Tape the outside surface of the window and back cut to form nice edges.  2" tape is good for this step.
To Do Glue small Silpruf standoffs at each cleco hole (using ultra black RTV)
To Do Apply a layer of Silpruf to the exposed inside edge of the window.
To Do Remove 1/4" masking tape marked with a #1.
To Do Let sit for 24 hours.
To Do Fit window to recess by trimming the Silpruf standoffs until window is flush with exterior surface.  Trimming the Silpruf standoffs with an angle cut seems to work well here.
To Do Tape the outside edge of the window recess such that the exterior surface and the wall of the recess are covered.
To Do Tape the inside edge of the window recess and back cut the tape to provide a smooth edge 
To Do Ensure all exposed areas that might get Silpruf on them are protected with tape or paper.
To Do Drill out cleco holes if inside tape covered any of them.
To Do Apply a thin layer of Silpruf to edge of window that was revealed when tape #1 was removed.
To Do Apply generous bead of Silpruf to the window recess.
To Do Install and cleco window with clean wood straps.
To Do Using small squeegee clean the excess Silpruf from both sides of the window.  Leave the 3/16" gap empty for now.
To Do Remove tape marked #2.
To Do Remove cleco's one at a time pulling up the tape that protects the Cabin top.  Clean out under the wood slat, install clean slat and then reinstall the cleco.  Do this for all cleco's.
To Do Let sit for at least 48 hours before removing cleco's.

Here are a few pictures of the process.  Some of these have already been posted on this blog.

Trimming window to fit recess opening.  Note the 3/16" gap around the edge of the window.

Fitting window with Popsicle stick pieces to keep it flush with the surface of the cabin top.

Small Silpruf standoffs glued to the cabin top at each cleco hole using Permatex Ultra black RTV.

Outside edge of window taped off and back cut flush with the window edge.  Its actually not flush because I held the razor at an angle so that the 1/16" rounded top edge would not be covered.

Inside surface of window with all three layers of tape as well as the gluing surface sanded with 120 grit for adhesion purposes.

Last layer of tape with the #1 annotated on the end that I will use to pull the tape up.

Outside surface taped and fiberglass protection.  As noted in my blog post I need to add more protection to the top edge as I found my hand touching the fiberglass during the clean up.  

Window installed after applying a generous bead of Silpruf and then cleaning out the excess squeeze out.  In this picture I have also completed the step where the cabin protection tape layer has been removed and the Popsicle sticks replaced.

Inside edge after cleanup/smoothing and tape #2 removal.  I could have removed the green tape as well here but I left it in place so that the Silpruf would dry and it would be less messy to remove.
Final look of window after 2 days of cure time.  Note the nice clean lines on the inside edge of the window.  The outside edge with the 3/16" gap looks messy now but after paint is applied I will come back and fill this gap in with a fresh batch of Silpruf.