In this video I mount some new fixed portlights using 3M VHB tape. VHB stands for Very High Bond, and it does exactly what it says it does! When installing polycarbonate or acrylic panels / portlights I’ve found this method to work extremely well. It eliminates the need for any kind of screw fasteners which typically result in cracking the material, provides a nice clean look and allows the poly / acrylic to expand and contract with temps without issue.
The specific tape I used was 3M VHB 5952 and can be found through a number of online retailers. At the time I ordered, I happened to find the best deal through an Ebay seller. I went with 1″ wide tape as it’s what my project called for, but it comes in different widths and roll lengths.
The caulking I used was Dow Corning 795 in black. Dow Corning 791 would also be a great choice. I typically order this material from here.
What I particularly like about this silicone is the working time and it’s bonding strength. Unlike most silicone’s, this caulking allows roughly 10 minutes of working time before it starts to skin over (most others allow a minute or less) so, you have plenty of time to smooth it over and pull the tape.
These portlights were roughly 24″ wide and 8″ tall. Each tube of caulking was able to glaze 3 portlights before it was empty.
One tip I would like to suggest for anyone looking to cut and install their own portlights would be to allow a generous gap / reveal of at least 1/8″ all the way around the polycarbonate. You’ll need this space to completely fill with silicone around the portlight and get a good seal.
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Materials, Tools, & Suppliers
- 3M VHB 5952 Tape
- Dow Corning 795