Cap & Trim Frequently Asked Questions ---- - Back to Install Details
 
 
-Design & Selection
 The seal between the Narrow Profile Cap and polycarbonate panel doesn't look weather tight. What do you recommend for roof with a shallow pitch? Properly installed, the Narrow Profile Cap provides an excellent seal, even on a 1/12 (5%) pitch. Glass and acrylic are hard materials, requiring a gasket type seal on the glazing system cap. Polycarbonate is a resilient material. When the Narrow Profile Cap is snugly installed, the pressure of the legs of the Cap causes the polycarbonate to give slightly, creating a watertight seal. One of the great advantages to polycarbonate is that gaskets are not required to achieve a watertight seal. The more parts of a glazing system, the more likelihood for leakage. Gaskets in glazing system caps will often shrink, creating a gap for water to enter. Also, because one sheet of polycarbonate runs from the ridge of a greenhouse to the overhanging eave, there are no horizontal joints, no impediments to water shedding off the glazing area, no water damming up and, consequently, leakage rarely occurs. The most often reported cause for leakage is loose Caps, (not tight enough when installed).
 I do not see vent tape in your drawings? Vent tape is typically used in U-Profiles of plastic that, not only yellow, but also fit loosely. Without vent tape these plastic U-Profiles allow bugs to enter. Our U-Profiles fit tight, vent tape not required. It is important to access our drawings and following these drawings carefully, should you choose to use our Install Systems. Using our components and misc. instructions from others will clearly lead to problems. No other company goes to the length we do to ensure a successful installation. Follow our guidelines to the letter and we ensure a quality installation. Plastic install components are junk. Aluminum will last, and you have a choice of colors.
 Where do I use silicone? Minimal use of silicone is required. See drawings above for the areas we suggest using silicone. Silicone may also be used at the interface of Freestanding Ridge or Lean-To-Ridge and Narrow Profile Cap (see drawing below) and where two Trim Components meet. Do not use silicone under Narrow Profile Cap. Silicone should be used to close at ends of Cap.
 How do I determine quantity of silicone required? One tube of silicone will produce 25 linear feet of 1/4" x 1/4" silicone bead. We sell plastic compatible, 100% silicone.
 My framing is 2 ft. on-center, but the sheet is 4 ft. Can I use the Cap to cover the 2x4 that supports the middle of the sheet? Yes, this will hide the 2x4 and make your greenhouse look more attractive.
 Where is Aluminum Tape used? Aluminum tape is generally used to seal the channels of polycarbonate at the top edge of roof sheets and top of gable end wall sheets. Flashing typically covers the top of the roof sheets (see Lean-To Ridge & Freestanding Ridge). The Corner Trim covers the top of gable end wall sheets and the edge of the roof sheets, at this transition. Use of the U-Profile in these applications would prevent flush fitting of Corner Trim, use aluminum tape and cover with Corner Trim (see Roof Corner). Please note, some applications such as a patio roof may necessitate use of U-Profile at the top edge of roof sheets. One may also have an application where the roof sheet hangs over the side of the rafter edge. Here we suggest only overhanging a few inches and use the U-profile to trim out the side edge of the sheet.
 Please offer some suggestions for purchasing ridge flashing. Use the Freestanding Ridge or Lean-To-Ridge details as a guideline. Print the page if the detail is appropriate for your application. Do a scale drawing of the flashing needed for your ridge. Draw so that the leg(s) of the flashing are tilted down 5° from the actual pitch of your roof. This will create a small amount of pressure against the polycarbonate sheet, useful in achieving a watertight installation. Sheet metal should be a minimum of .019" aluminum or 30 gauge steel. Aluminum is easy to fasten through, easy to cut, but is a little flimsy and care is required in handling. Steel is more sturdy, harder to cut and requires pre drilling prior to fastening. Availability at your local sheet metal shop may be the limiting factor. Look in the Yellow Pages under Sheet Metal Work. Some shops, especially those that cater to glass installation contractors, will inventory bright glossy white and medium architectural bronze in the thickness you will be looking for.
 
-Installation - - -SSee Cap & Trim Install Manual in Adobe Acrobat
 How do I install flashing? When installing the flashing, first lay in place and mark where the flashing overlaps the Cap at sheet seams. Notch the flange at these locations to fit the Cap. When installed, the flashing will rest flat on the polycarbonate and the Cap. Failure to cut out for the Cap will result in a gap between the polycarbonate and the flashing, wavy looking flashing and a poor weather seal. Overlap seams a minimum of 4". Do not cut to length as this will create a slight curl at cut and an uneven overlap. If the overlap ends up being 4 ft., so be it. The only cutting required is an easy to cut, curved notch where the Narrow Profile Cap slides under the flashing. See drawing below.
 Please suggest touch up paint? Our white is fairly easy match to common gloss, appliance white spray paint. For the bronze we suggest Rust-Oleum, Bright Coat, Metallic Finish - Dark Bronze #7713. An exact match is rather difficult. Painting surrounding materials, like flashing, with a spray touch paint works quite well. Always follow safety instructions on the can.
 
Also see Freestanding Ridge or Lean-To-Ridge and Narrow Profile Cap for details that will be helpful in understanding why and how to do this notch.
 
 
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