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A Technical Review of Proper Masonry Detailing
A Technical Review of Proper Masonry Detailing
Matthew A. Dettman, P.E.Matthew A. Dettman, P.E.
OverviewOverview Water Penetration ResistanceWater Penetration Resistance
• Wall SystemsWall Systems• Flashing and Weep holesFlashing and Weep holes• CoatingsCoatings
Differential MovementDifferential Movement• CrackingCracking• Movement JointsMovement Joints
Problems related to water penetrationProblems related to water penetration Water entry into interiorWater entry into interior EfflorescenceEfflorescence SpallingSpalling CorrosionCorrosion Reduced insulating capacityReduced insulating capacity Staining / Mold / MildewStaining / Mold / Mildew
Keys to Providing Water Penetration ResistanceKeys to Providing Water Penetration Resistance
Quality MaterialsQuality Materials
Good ConstructionGood Construction
Proper detailingProper detailing
MaintenanceMaintenance
Keys to Providing Water Penetration ResistanceKeys to Providing Water Penetration Resistance
Quality MaterialsQuality Materials
Good ConstructionGood Construction
Proper detailingProper detailing
MaintenanceMaintenance
Three Basic Wall TypesThree Basic Wall Types
Drainage WallDrainage Wall
Barrier WallBarrier Wall
Single Wythe WallSingle Wythe Wall
Drainage WallDrainage Wall
Drainage WallDrainage Wall
Water travels down back side of outer Water travels down back side of outer wythe, collected on flashing, and wythe, collected on flashing, and channeled to exterior through weep channeled to exterior through weep holesholes
Examples: Examples: • Cavity wallsCavity walls• Masonry veneer wallsMasonry veneer walls• Rain screen wallsRain screen walls
Drainage Walls RequirementsDrainage Walls Requirements
2 to 4 ½ inch 2 to 4 ½ inch clear cavity clear cavity
Flashing and Flashing and weep holes to weep holes to channel out channel out excessive water excessive water
Rain Screen WallRain Screen Wall
Equalizes pressure within cavityEqualizes pressure within cavity Vents at top and bottom of wall or panelVents at top and bottom of wall or panel Flashing and weep holesFlashing and weep holes CompartmentalizedCompartmentalized Allows for ventilation and evaporationAllows for ventilation and evaporation
Barrier WallBarrier Wall Collar joint Collar joint
between wythes between wythes acts a barrier to acts a barrier to moisture along moisture along with the thickness with the thickness of the wallof the wall
ExamplesExamples• Brick and Block Brick and Block
Composite Wall Composite Wall
Barrier WallBarrier Wall
Voids allow Voids allow water penetrationwater penetration
Must be filled Must be filled solid with mortar solid with mortar or groutor grout
Single Wythe WallsSingle Wythe Walls
Single WytheSingle Wythe Masonry units with Masonry units with
coating or integral water coating or integral water repellentrepellent
Mortar with integral Mortar with integral water repellentwater repellent
Through-wall flashingThrough-wall flashing Weep HolesWeep Holes VentsVents
Flashing DetailsFlashing Details
LocationsLocations
PlacementPlacement
Flashing LocationsFlashing Locations base of wallbase of wall sillssills heads of windowsheads of windows at shelf anglesat shelf angles copingscopings lower wall/ higher roof intersectionlower wall/ higher roof intersection other discontinuities in air spaceother discontinuities in air space
Good Flashing DetailGood Flashing Detail
Poor DetailPoor Detail
Drip EdgeDrip Edge
SS Drip EdgeSS Drip Edge
Shelf AnglesShelf Angles
Flashing Single Wythe Walls
Flashing Single Wythe Walls
Flashing with Shear Transfer
Flashing with Shear Transfer
Flashing Reinforced Wall
Flashing Reinforced Wall
End DamsEnd Dams
Flashing LapsFlashing Laps
Drainage MaterialsDrainage Materials
Weep HolesWeep Holes
Weep TubesWeep Tubes
Vent Weep HolesVent Weep Holes
Rope WicksRope Wicks
Flashing MaterialsFlashing Materials
Sheet Metal Sheet Metal CompositesComposites Plastic and RubberPlastic and Rubber
CompoundsCompounds
Stainless Steel
Cold-Rolled Copper
Galvanized Steel
Durable, non staining
Durable
Easy to paint and durable
Hard to solder and form
Damaged by excessive flexing and can stain
Difficult to solder, corrodes early in acidic and salty air
Material Advantages Disadvantages
Sheet MetalsSheet Metals
Lead-coated copper
Copper laminates
Flexible, durable, non-staining
Easy to form
Difficult to solder, damaged by excessive flexing, metal drip edge suggested
Degrades in UV light, more easily torn than metal
Material Advantages Disadvantages
CompositesComposites
EPDM
Rubberized asphalt
PVC
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
Material Advantages Disadvantages
Plastics and Rubber CompoundsPlastics and Rubber Compounds
Bldg felt and poly sheetingBldg felt and poly sheeting
Colorless CoatingsColorless Coatings
Used for a variety of reasonsUsed for a variety of reasons Recommended for Concrete MasonryRecommended for Concrete Masonry Questionable for Clay MasonryQuestionable for Clay Masonry
Possible DangersPossible Dangers
Water can still penetrateWater can still penetrate Could cause spallingCould cause spalling If efflorescence occurs under coating, If efflorescence occurs under coating,
it may be impossible to removeit may be impossible to remove Recoating will be necessaryRecoating will be necessary
Coating TypesCoating Types
Colorless CoatingsColorless Coatings
PaintsPaints
Colorless CoatingsColorless Coatings
Penetrating Penetrating • SilanesSilanes• SiloxanesSiloxanes
Film-formingFilm-forming• AcrylicsAcrylics• StearatesStearates
Coating TypesCoating Types
PaintsPaints• Cement basedCement based• LatexLatex• AlkydAlkyd• Oil-based PaintsOil-based Paints
Differential MovementDifferential Movement
MovementsMovements• Temperature MovementTemperature Movement• Moisture MovementMoisture Movement• Elastic DeformationElastic Deformation
Movement JointsMovement Joints• DesignDesign• PlacementPlacement
Causes of CrackingCauses of Cracking
Differential MovementDifferential Movement RestraintRestraint SettlementSettlement Elastic DeformationsElastic Deformations CreepCreep
Types of MovementTypes of Movement
Temperature MovementTemperature Movement
Coefficient of Thermal ExpansionCoefficient of Thermal Expansion• Brick = 3.6 x 10Brick = 3.6 x 10-6-6
• Concrete Masonry = 4.3 x 10Concrete Masonry = 4.3 x 10-6-6
• Aluminum = 12.8 x 10Aluminum = 12.8 x 10-6-6
• Steel = 6.5 x 10Steel = 6.5 x 10-6-6
Moisture MovementMoisture Movement
Brick - irreversible expansionBrick - irreversible expansion
Concrete masonry – drying shrinkage Concrete masonry – drying shrinkage and carbonation and carbonation
Types of Movement JointsTypes of Movement Joints
Expansion Joint - Brick MasonryExpansion Joint - Brick Masonry
Control Joint - Concrete MasonryControl Joint - Concrete Masonry
Building Joint - StructuresBuilding Joint - Structures
Expansion JointExpansion Joint
Used in Clay MasonryUsed in Clay Masonry Used to separate brick into sections so Used to separate brick into sections so
cracking will not occurcracking will not occur Horizontal / VerticalHorizontal / Vertical Entire joint is unobstructed and formed Entire joint is unobstructed and formed
from a highly elastic, continuous from a highly elastic, continuous materialmaterial
Types of Expansion Joints(Details)
Types of Expansion Joints(Details)
Expansion JointExpansion Joint
Typical Spacing and Locations of Expansion JointsTypical Spacing and Locations of Expansion Joints
Long WallsLong Walls CornersCorners Setbacks & OffsetsSetbacks & Offsets Parapet wallsParapet walls Beneath shelf anglesBeneath shelf angles
Expansion Joints at CornersExpansion Joints at Corners
Horizontal Expansion JointHorizontal Expansion Joint
False Horizontal EJFalse Horizontal EJ
Hiding Expansion JointsHiding Expansion Joints
Control JointControl Joint
Used in Concrete MasonryUsed in Concrete Masonry• Relieve horizontal tensile stressesRelieve horizontal tensile stresses• Reduce restraint and permit longitudinal Reduce restraint and permit longitudinal
movementmovement• Separate dissimilar materialsSeparate dissimilar materials
Types of Control JointsTypes of Control Joints
Pre-formed gasketPre-formed gasket
Formed paperFormed paper
Special shape unitsSpecial shape units
Pre-formed GasketPre-formed Gasket
Formed Paper (also known as Michigan Joint)Formed Paper (also known as Michigan Joint)
Special Shape UnitSpecial Shape Unit
Joint Reinforcement at CJJoint Reinforcement at CJ
Bond BeamsBond Beams
Do not cut bond Do not cut bond beam beam reinforcement reinforcement unless specifically unless specifically indicated on the indicated on the plansplans
Control Joint LocationsControl Joint Locations
Control Joint SpacingControl Joint Spacing
Two methods:Two methods:
• EmpiricalEmpirical based on historical performancebased on historical performance
• EngineeredEngineered based on a crack control coefficientbased on a crack control coefficient
Empirical Control Joint CriteriaEmpirical Control Joint Criteria Spacing for above grade exposed concrete Spacing for above grade exposed concrete
masonry wallsmasonry walls• Distance between joints is the lesser of:Distance between joints is the lesser of:• Length to height ratio Length to height ratio oror
1 ½ 1 ½ 25 feet25 feet• Notes:Notes:
Based on horizontal reinforcement of 0.025 in.Based on horizontal reinforcement of 0.025 in.22/ft/ft Applies to both Type I and Type II unitsApplies to both Type I and Type II units Can be modified based on local experienceCan be modified based on local experience
Engineered Crack Control CriteriaEngineered Crack Control Criteria
Crack Control CoefficientCrack Control Coefficient
in./in. (mm/mm)in./in. (mm/mm)
________________ __________ __________0.0010 ___ 0.0015________________ __________ __________0.0010 ___ 0.0015
Maximum wall Maximum wall _length, ft (m)_________25 (7.62)__20 (6.10)_length, ft (m)_________25 (7.62)__20 (6.10)
panel dimensions_ length/height ratio_ _____2 ½ ______2___panel dimensions_ length/height ratio_ _____2 ½ ______2___
Min. horizontal reinf. ratio AMin. horizontal reinf. ratio Ass/A/Ann 0.0007 0.0007 0.0007 0.0007
Notes:Notes:
AAss = cross-sectional area of steel, in = cross-sectional area of steel, in22/ft (mm/ft (mm22/m)/m)
AAnn = net cross-sectional area of masonry, in = net cross-sectional area of masonry, in22/ft (mm/ft (mm22/m)/m)
Criteria for Controlling Cracking in Reinforced Concrete Masonry Walls
Engineered Crack Control Criteria (cont.)Engineered Crack Control Criteria (cont.)Notes:Notes: Need not apply if ANeed not apply if Ass/A/Ann >> 0.002 - see Table 4. 0.002 - see Table 4. See Table 3 for ASee Table 3 for Ass/A/Ann = 0.0007 minimum = 0.0007 minimum
requirement.requirement. Minimum reinforcement ratio need not apply if Minimum reinforcement ratio need not apply if
length is length is << ½ maximum length shown in table. ½ maximum length shown in table. CCC’s less than 0.0010 may be available in CCC’s less than 0.0010 may be available in
some areas and spacing should be adjusted some areas and spacing should be adjusted accordingly.accordingly.
Control joint spacing may be adjusted up or Control joint spacing may be adjusted up or down based on local experience.down based on local experience.
Table 3—Maximum Spacing of Hor. Reinf. for A s > 0.0007An1
Wallthickin.
Maximum spacing of horizontal reinforcement, in. (mm)Reinforcement size
#5 #4 #3 4x3/16
4 x 8gage
4 x 9gage
2x3/16
2 x 8gage
2 x 9gage
Ungrouted or partially grouted walls
6 144 128 64 72 56 48 40 24 24
8 144 96 40 64 48 40 32 24 16
10 136 80 32 56 40 32 16 16 16
12 120 72 24 48 40 32 16 16 16
1. An includes cross-sectional area of grout in bond beams.
Brick and Block TogetherBrick and Block Together
Align Align Expansion Expansion Joints and Joints and Control Control JointsJoints
Bond BreaksBond Breaks
Use to Use to separate bands separate bands of different of different masonry typesmasonry types