37 Flashing MaterialsSheet MetalCompositesPlastic and RubberCompounds
38 Sheet Metals Material Advantages Disadvantages Hard to solder and form Damaged by excessive flexing and can stainDifficult to solder, corrodes early in acidic and salty airStainless SteelCold-Rolled CopperGalvanized SteelDurable, non stainingDurableEasy to paint and durableStainless steel is technically any of a large and complex group of corrosion resistant iron chromium alloys possessing excellent weather and chemical resisting properties. Preformed sections must be properly sized so that modification on the site is minimal. Typical: Type 304 stainless steel with a minimum thickness of in. (0.25 mm). Lapped sections must be soldered. Stainless steel drip edges used in combination with other flashing materials also works well.Copper is a non-ferrous metal with good ductility. Like stainless steel, it also possesses excellent weather and chemical resistant properties. Preformed sections are easier to modify in the field. Be careful of green patina stains!Galvanized steel is less expensive than stainless, but is more subject to attack from salts and acids. The galvanized coating may also crack at bends, lowering the corrosion resistance. As with stainless, hard to solder laps.
39 Composites Material Advantages Disadvantages Difficult to solder, damaged by excessive flexing, metal drip edge suggestedDegrades in UV light, more easily torn than metalLead-coated copperCopper laminatesFlexible, durable, non-stainingEasy to formSome companies provide flashings that have combined metals and plastics.Copper composites are popular since they combine the durability and malleability of copper with non-staining characteristics of the plastic coating.Composites containing aluminum should be avoided.
40 Plastics and Rubber Compounds MaterialAdvantagesDisadvantagesFlexible, easy to form, non-stainingFully adhered, separate lap adhesive not needed, self healing, flexible, easy to form and joinEasy to form and join, non-staining, low costAesthetics if not used with a metal drip edge, full support recommendedFull support required, degrades in UV light, metal drip edge requiredEasily damaged, full support required, metal drip edge required, questionable durabilityEPDMRubberized asphaltPVCPlastics are categorized as polymeric materials of large molecular weight, usually polyvinyl chloride (PVC) or polyethylene. Manufacturers of plastic flashings should be consulted for documentation establishing the longevity of the plastic in a caustic environment (pH = 12.5 to 13.5), the composition of the plastic, ease of working at temperatures ranging from 20 to 100°F and ability to withstand exposure to ultraviolet light.Ethylene Propylene Diene Monomer (EPDM) is a synthetic rubber that is used as a single ply roofing membrane as well as flashing. It has better low temperature performance than PVC and will not embrittle. It offers ultraviolet light and ozone resistance and can be left exposed.Self-adhering, rubberized asphalt membranes consist of a composite of flexible plastic film for puncture and tear resistance combined with a rubberized asphalt adhesive layer. This material adheres to itself, requiring less effort to seal laps or corners which speeds installation. It also self-adhered to the substrate which prevents water form migrating under the flashing and is self-healing in the event of punctures. However, it should not be applied to damp, dirty, or dusty surfaces and has a typical lower limit installation temperature of 25 °F. Because it degrades in the presence of extended UV exposure, it should not be left exposed and requires a metal drip edge.
50 Temperature Movement Coefficient of Thermal Expansion Brick = 3.6 x 10-6Concrete Masonry = 4.3 x 10-6Aluminum = 12.8 x 10-6Steel = 6.5 x 10-6
51 Moisture Movement Brick - irreversible expansion Concrete masonry – drying shrinkage and carbonation
52 Types of Movement Joints Expansion Joint - Brick MasonryControl Joint - Concrete MasonryBuilding Joint - Structures
53 Expansion Joint Used in Clay Masonry Used to separate brick into sections so cracking will not occurHorizontal / VerticalEntire joint is unobstructed and formed from a highly elastic, continuous material
69 Control Joint Spacing Two methods: Empirical Engineered based on historical performanceEngineeredbased on a crack control coefficient
70 Empirical Control Joint Criteria Spacing for above grade exposed concrete masonry wallsDistance between joints is the lesser of:Length to height ratio or1 ½ feetNotes:Based on horizontal reinforcement of in.2/ftApplies to both Type I and Type II unitsCan be modified based on local experience
71 Engineered Crack Control Criteria Criteria for Controlling Cracking in Reinforced Concrete Masonry WallsCrack Control Coefficientin./in. (mm/mm)________________ __________ __________ ___Maximum wall _length, ft (m)_________25 (7.62)__20 (6.10)panel dimensions_ length/height ratio_ _____2 ½ ______2___Min. horizontal reinf. ratio As/AnNotes:As = cross-sectional area of steel, in2/ft (mm2/m)An = net cross-sectional area of masonry, in2/ft (mm2/m)
72 Engineered Crack Control Criteria (cont.) Notes:Need not apply if As/An > see Table 4.See Table 3 for As/An = minimum requirement.Minimum reinforcement ratio need not apply if length is < ½ maximum length shown in table.CCC’s less than may be available in some areas and spacing should be adjusted accordingly.Control joint spacing may be adjusted up or down based on local experience.
73 Table 3—Maximum Spacing of Hor. Reinf. for A > 0.0007A 1Wallthickin.Maximum spacing of horizontal reinforcement, in. (mm)Reinforcement size#5#4#34x3/164 x 8gage4 x 92x2 x 82 x 9Ungrouted or partially grouted walls614412864725648402489632161013680121201. Aincludes cross-sectional area of grout in bond beams.
74 Brick and Block Together Align Expansion Joints and Control Joints
75 Bond BreaksUse to separate bands of different masonry types