The following is taken from the Sheet Metal and Air Conditioning Contractors’ National Association’s Architectural Sheet Metal Manual.
Figure 2-9 illustrates an installation of porcelain enamel gravel-stop-fascia systems. Since porcelain enamel should not be field cut, it is necessary to determine exact lengths and miters from field measurements. In measuring, three-sixteenths inches (5 millimeters) should be allowed between sections for expansion and sealing.
Figure 2-9A shows a gravel-stop fascia system installed on a raised curb. The wood nailer has been cut to form a cant. Panels are secured at top by gravel-stop flange and at ends by use of stainless steel clips (Detail 1).
Care should be taken to be sure fascia is level.
The gravel-stop flange is attached over roofing using fasteners and watertight washers.
Figure 2-9B shows a gravel-stop-fascia system employing a two-piece fascia panel. The lower panel is held in position by a stainless steel cleat at the bottom and a stainless steel clip at the top (details 2 and 3). The clip must be inserted into the lower panel and aligned before being attached to the wood backing.
The gravel-stop flange is attached through the envelope fold and then stripped-in by the roofer. Formed gravel-stop may be any material that is suitable for contact with the fascia material. If it is to be color-coordinated with the fascia, designate the color.
Joints in the fascia should be sealed as indicated on the drawing. Joints in the gravel-stop flange should be provided with a cover plate set in mastic and fastened between sections.
Joints and cornersFigure 2-10 shows a corner and a joint for a typical extruded aluminum gravel-stop fascia system. The corner of the gravel-stop fascia must be mitered and welded. Each leg of the corner should not exceed 18 inches (480 mm) in length.
To form the joint, a backup plate of 0.025 inches (0.6 mm) aluminum is placed on top of the envelope fold. The sections of gravel-stop are fastened in place over the backup plate, leaving room for expansion between sections. Compatible sealant is placed in the joint and a 6-inch aluminum cover plate is attached by screws between the sections. The section of extrusion should be fastened to the nailer at the midpoint in order to direct expansion movement.
Figure 2-10B illustrates the method of installing nonwelded extruded fascia and soffit systems. Backup plates of 0.025 inches (0.6 mm) aluminum are used at the corners and at all joints, as shown. Corners in the gravel-stop are mitered and welded. Corners in the fascia are mitered and butted or are arc-welded. Joints in the fascia plate and soffit should coincide with joints in the gravel-stop.
Information about joint and corner systems for shapes not shown here may be found in manufacturers’ catalogs.
To order copies of SMACNA’s Architectural Sheet Metal Manual, write 4201 Lafayette Center Drive, Chantilly, VA 20151-1209; seewww.smacna.orgon the Internet.