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