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A Technical Review of Proper Masonry Detailing. Matthew A. Dettman, P.E. Overview. Water Penetration Resistance Wall Systems Flashing and Weep holes Coatings Differential Movement Cracking Movement Joints. Problems related to water penetration. Water entry into interior Efflorescence
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A Technical Review of Proper Masonry Detailing Matthew A. Dettman, P.E.
Overview • Water Penetration Resistance • Wall Systems • Flashing and Weep holes • Coatings • Differential Movement • Cracking • Movement Joints
Problems related to water penetration • Water entry into interior • Efflorescence • Spalling • Corrosion • Reduced insulating capacity • Staining / Mold / Mildew
Keys to Providing Water Penetration Resistance • Quality Materials • Good Construction • Proper detailing • Maintenance
Keys to Providing Water Penetration Resistance • Quality Materials • Good Construction • Proper detailing • Maintenance
Three Basic Wall Types • Drainage Wall • Barrier Wall • Single Wythe Wall
Drainage Wall • Water travels down back side of outer wythe, collected on flashing, and channeled to exterior through weep holes • Examples: • Cavity walls • Masonry veneer walls • Rain screen walls
Drainage Walls Requirements • 2 to 4 ½ inch clear cavity • Flashing and weep holes to channel out excessive water
Rain Screen Wall • Equalizes pressure within cavity • Vents at top and bottom of wall or panel • Flashing and weep holes • Compartmentalized • Allows for ventilation and evaporation
Barrier Wall • Collar joint between wythes acts a barrier to moisture along with the thickness of the wall • Examples • Brick and Block Composite Wall
Barrier Wall • Voids allow water penetration • Must be filled solid with mortar or grout
Single Wythe • Masonry units with coating or integral water repellent • Mortar with integral water repellent • Through-wall flashing • Weep Holes • Vents
Flashing Details • Locations • Placement
Flashing Locations • base of wall • sills • heads of windows • at shelf angles • copings • lower wall/ higher roof intersection • other discontinuities in air space
Flashing Materials • Sheet Metal • Composites • Plastic and Rubber Compounds
Sheet Metals Advantages Disadvantages Material Hard to solder and form Damaged by excessive flexing and can stain Difficult to solder, corrodes early in acidic and salty air Durable, non staining Durable Easy to paint and durable Stainless Steel Cold-Rolled Copper Galvanized Steel
Composites Advantages Disadvantages Material Difficult to solder, damaged by excessive flexing, metal drip edge suggested Degrades in UV light, more easily torn than metal Flexible, durable, non-staining Easy to form Lead-coated copper Copper laminates
Plastics and Rubber Compounds Advantages Disadvantages Material Flexible, easy to form, non-staining Fully adhered, separate lap adhesive not needed, self healing, flexible, easy to form and join Easy to form and join, non-staining, low cost Aesthetics if not used with a metal drip edge, full support recommended Full support required, degrades in UV light, metal drip edge required Easily damaged, full support required, metal drip edge required, questionable durability EPDM Rubberized asphalt PVC
Colorless Coatings • Used for a variety of reasons • Recommended for Concrete Masonry • Questionable for Clay Masonry
Possible Dangers • Water can still penetrate • Could cause spalling • If efflorescence occurs under coating, it may be impossible to remove • Recoating will be necessary
Coating Types • Colorless Coatings • Paints
Colorless Coatings • Penetrating • Silanes • Siloxanes • Film-forming • Acrylics • Stearates
Coating Types • Paints • Cement based • Latex • Alkyd • Oil-based Paints
Differential Movement • Movements • Temperature Movement • Moisture Movement • Elastic Deformation • Movement Joints • Design • Placement
Causes of Cracking • Differential Movement • Restraint • Settlement • Elastic Deformations • Creep
Temperature Movement • Coefficient of Thermal Expansion • Brick = 3.6 x 10-6 • Concrete Masonry = 4.3 x 10-6 • Aluminum = 12.8 x 10-6 • Steel = 6.5 x 10-6