There is a wide range of rooftop supports available on the market. A variety of products are designed to accommodate pipes, struts, pavers, and related equipment of all sizes. Some of these are designed to be loose laid, which for many installations such as electrical conduit or pipelines is acceptable. Loose laid supports offer the advantage of reducing labor costs.
However, in conditions where there are heavy rain patterns, snow and ice, high winds or seismic concerns, attachment makes for a more secure installation. Methods of attachment include mechanical fasteners such as standard insulation roofing screws and/or the use of an adhesive/sealant. Securing supports using one or both of these methods is especially important when installing solar arrays.
KnuckleHeads feature a round universal base with a 7” diameter which in itself provides a higher level of stability relative to competitive designs because the circular shape evenly distributes weight.
For increased stability, KnuckleHeads can be efficiently attached with mechanical fasteners. The interior of the base features two holes through which insulation roofing screws can be driven into the structural deck. KnuckleHeads also offer a feature that is unique to rooftop supports: they can be bonded directly to the roof substrate using Chem Link M-1® Structural Adhesive Sealant. Many supports on the market are composed of polypropylene or rubber which resists adhesive bonding. KnuckleHeads are composed of reinforced nylon to which M-1 will bond securely with shear strengths up to 400 psi. One option that contractors and specifiers have is to bond KnuckleHeads using only adhesive, avoiding any penetration of the roof’s surface. M-1 can even be used to bond the pipe or strut within the head itself.
However, when the roof is penetrated using mechanical fasteners, there may be concern from the membrane manufacturer over the warranty. Green Link offers Halo Target Flashings consisting of PVC, MB, SBS TPO and EPDM membranes which can slide over the KnuckleHead and heat sealed in place. Prefabricated pipe boots can also be used. For additional protection against leaks, M-1 can be used to seal the heads of the screws and the perimeter of the base before the Halo Target is installed.
While attachment is not necessary to stabilize roof supports in many cases, it is advisable for some installations, in particular for solar arrays, which are sensitive to high winds. KnuckleHead Solar Supports mechanically attached and bonded to the roof membrane have demonstrated wind uplift values in excess of 700 lbs.