Setting Blocks are used to position the glass into the frame. Setting blocks are generally produced in EPDM or Neoprene with a Shore A hardness of 80-90 durometer. There are other durometers available for your special glazing needs. Other polymers, such as silicone may be used as glazing systems require.
When used in combination with a heel and toe beads, they should be first buttered with sealant, then placed prior to installing glass. This ensures an uninterrupted seal between the glass and sash member.
As a general rule, setting blocks should be centered at 1/4″ points. However, engineering requirements may dictate an alternate location for block placement. Setting blocks should be designed so as to prevent shifting, provide lifelong support of the full thickness of the infill, establish minimum recommended bite and edge clearance, allow for the flow of water by the block to the drainage system,and provide for the installation of glazing seals and assembly of the system. Setting block lengths are determined by the glass square footage. The block length is calculated; 0.1 inch per square foot of the glass, but not less than 4 inches.
Setting Blocks are desirable for all glass, even if the glass is under 50 United Inches, except when set in wood or commercial metal sash. Organic sealed insulated glass should always be set on blocks. For glass over 50 United Inches it is required to use two setting blocks at the bottom of the glass,spaced 1/4 of the width in from each end. Where possible, the blocks should be 1/16″ less than the full width of glass provided they will be of a resilient type and will have long life. The length of the block depends on the square foot of the glass. (The length of the block should be 0.1 times the glass area). The minimum length should be 4″. The height of the block depends on a number of factors,such as size of glass, depth of rabbet and thickness of glass. (Refer to the FMGA Glazing Manual).
Setting Blocks are not usually used when a rubber U channel is used in conjunction with monolithic glass. However, some manufacturers require setting blocks for their units even with monolithic glass. When installing glass thicker than 1/8 and greater than 5 sq. ft. in entrance doors or side-hinged sash,it is often necessary to place only one setting block under the glass. It should be directly over the pivot point on the entrance door or close to the hinged side of the sash. Since only one setting block is used below the glass, it must also be permanently blocked at the side near the top opposite the hinge or pivot. Some entrance doors have these blocks built into the stile and are adjustable. Note: Safety glazing is required in entrance doors.