Base & Cap SystemFrequently Asked Questions -------- - Back to Home Page
-Design & Selection
 The seal between the Cap and polycarbonate panel doesn't look weather tight. What do you recommend for roof with a shallow pitch? Properly installed, the 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 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. Our Base and Cap System has no gaskets and requires no silicone where the Cap meets the polycarbonate. 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 that fit loosely. Without vent tape these U-Profiles allow water, dust, pollen anf bugs to enter. Our U-Profiles fit tight, vent tape not required. It is important to access our drawings and following these drawings carefeully, 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 with our system 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. Do not use silicone under Cap, except at lower edge of roof.
 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 existing rafter framing is 4 ft. on-center, but the sheet is 4 ft. I would like to use your Base & Cap System. What do you suggest? You can cut the sheet down to 47-1/8 to 47-1/4.
 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 using the U-profile to trim out the side edge of the sheet.
 Please offer some suggestions for purchasing ridge flashing. Use the Lean-To Ridge & Freestanding 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.
 Do you offer any type of sealing or flashing material, other than silicone, for side of polycarbonate meeting existing roofing or wall. Carlisle Hardcast manufactures a 15 mil Butyl Adhesive Roll Roof Flashing Tape (Foil-Grip) that is used for a variety of roofing applications. This tape comes in 3" wide, and is available with an aluminum foil backing. Install the polycarbonate so it almost meets adjacent material and cover the joint with the Flashing Tape. Make sure the polycarbonate is securely fastened to the structure below with the screws we sell. See pdf version of Foil-Grip tech & install data sheet.
 I am building a sunroom or greenhouse and would like polycarbonate and the Base & Cap System on the roof and glass on the vertical walls. We recommend filling wall openings with vinyl windows and patio doors. Windows may be custom sizes and door sizes are easy to work around. Fill in above gable end windows or doors with polycarbonate.
-Installation see Install Guide in Adobe Acrobat.
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