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Masonry...

Being the study of brick, block,and stacked stone

Simple way to build

• Stacking stone on stone…when there was no stone• Adobe…’earth-stone’ - mud straw, clay & secret

ingredient (dung) 5,000 years old• Fired clay brick about the same age• Concrete masonry unit approx 1915• Glass masonry unit approx. 1937

Key innovators

• Eutruscan, Meso-Americans : Corbel …(incrementalcantelievers)

• Greece, Egypt …lintels• Roman….arches and vaults• Arabic … vaults• Europe … Flying Buttress

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Brickmaking

• Soft mud process - for hand pressing 20-30% water• Dry press - for machine pressing 10% water• Stiff mud - extruded, wire cut column of brick 12 -

15% water

• Dry 1-2 days• Fire in kiln

Part I… the brick masonry unit

• The brick has been abasic building block formasonry construction forthousands of years.

• It’s size is generallybased on awidth/length/height thatis easy to pick up andposition with one hand

The basic brickwall

• The brick wall prior to1940 was most oftensolid brick.

• Bricks were laid up sideby side, each verticalrow of bricks beingcalled a wythe

• Each horizontal layer ofbrick is called a course.This is a plan view of astretcher course for atwo wythe wall.

Wythe #2

Wythe #1

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Keeping ittogether

• Bricks would be laidcross-wise to tie thewythes together. Theseare header bricks.

• Header bricks could bea whole horizontal layer(course) or beinterspersed withstretcher courses

Wythe #2

Wythe #1

Bonding Brick 2

• Alternating stretchersand headers in eachhorizontal courseproduces the Flemishbond

• A row of headers every6th horizontal coursewith running bond in-between produces aCommon bond

Sructural & Non-structuralbonds

• Overlapping stretchers withno headers produces theRunning bond, the most basicstructural bond (and a tip-offthat this is only a one wytheveneer!) But overlap in thebed joints provides somemechanical keying actionbetween courses, givingsome structural ability toresist lateral loads.

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No key…no structure

• Aligning the head jointswith all stretchersproduces the stackbond. Since no bedjoints overlap, there islittle mechanical keyingbetween the coursesmaking this the weakest(considerednonstructural) bond.

Every face has a name

If we see the longface horizontally, it’scalled a stretcher

Turn the long facevertical and it’s asoldier

More faces, more namesThe end face of thebrick, seenhorizontally is aheader. The header isusually used to tie thewythes together

The end face of thebrick, seen verticallyis a rowlock, oftenused for window sillsand tops of walls.

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Sailors & Flashers

The side face of thebrick, seen verticallyis a sailor

The side face of thebrick, seenhorizontally is aflasher

Brick sizes

• Name width height length• Modular 3 5/8” 2 1/4” 7 5/8”• Standard 3 3/4” 2 1/4” 8”• Roman 3 5/8” 1 5/8” 11 5/8”• Norman 3 5/8” 2 1/4” 11 5/8”• Jumbo 5 5/8” 3 5/8” 11 5/8”

Cores• The holes (cores) make

the brick lighter, easierto handle.

• They also make a moreeven firing of the claypossible

• They help establish amechanical key type ofjoint from one brick toanother as the mortarsqueezes into the cores

• When the mortar cures,it would have to besheared off for the brickto move sideways

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Brick & weathering• Generally the longer

a brick is fired, theharder it will get.

• Types:– NW for Negligible

Weathering exposure(extreme South Florida,South Texas)

– MW for ModerateWeathering exposure.(not as many freeze /thaw cycles per season)

– SW for SevereWeathering exposure.(many freeze-thawcycles per season)

Quality• FBX-Most precise color / size• FBS - close size precision / wide color variation• FBA - non-uniform size / color

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Mortar• Not Glue! Makes mechanical bond to the brick,

resists movement by shear.– Types

• ‘M’ = high strength 2,500psi used where masonry is exposed tosevere frost, frost below grade, or high lateral loads

• ‘S’ = medium high strength 1,800psi used for normalcompressive loads

• ‘N’ = medium strength 750 psi general above grade use• ‘O’ = medium to low strength, 350 psi for non-loadbearing

interior partitions– Mortar components: Portland cement (for strength); hydrated

lime (for workability); aggregate - sand (filler); water (for thehydration process)

– Begins to set up in 90 min. Only re-temper (add water) once

Joint width• Typically, mortar joints

are 3/8 of an inch thick.• Dimensions of brick

usually take this intoaccount, the 2 1/8”thickness of a modularbrick, added to the 3/8mortar joint (x 3courses) gives the 8inch high masonrymodule.

3/8

2 1/8”

3 5/8” 3/8”

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Tooled…concave

• The most common wayto finish a mortar joint isto force a rod across themortar as it sets up.

• This compresses themortar, increasing it’smoisture resistance andmakes a smooth surfacewith no place to holdrain, or snow, or sleet, orice.

Raked• To increase the horizontal

emphasis of his buildings,Frank Lloyd Wright wouldspecify a raked joint for thebed joints….in a dark mortarcolor; a flush joint for thehead joints …in a colormatching the brick. (youmight have to buy themasons a lot of coffee to getthis done today)

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Raked subtracts• The raked joint is made by

scraping out mortar to thedepth specified by thearchitect.

• It leaves a shelf for snow, ice,rain… so the brick should betop quality (SW)

• The mortar is notcompressed by raking so ismore porous. Should be thebest quality (M)

• But it makes the best shadow

Weathered• An alternative to the raked

joint is the weathered orstruck joint.

• Like the raked it joint it uses aprocess where mortar isscraped out of the joint.

• Unlike the raked joint thisjoint leaves no shelf formoisture to build up on, butstill makes a deep preciseshadow.

Historic

• The beaded joint was aneffort to bring precisionto the mortar when thebrick was imprecise.

• The projecting bead,formed by pushing aslotted rod into & alongthe mortar would make aprecise line and shadow,tricking the eye into aperception of precision.

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Vee

• The ‘V’ or vee joint isanother mortar jointformed by compressinga square rod into themortar.

• This compacts themortar & helps it resistmortar penetration.

Flush• Perhaps the simplest joint is

the flush joint. Mortarprojecting beyond the face ofthe brick is scraped flush withthe surface of the brick.

• Since the mortar is scrapedoff, there is no compressing ofthe mortar, and it remains asporous as the raked joint.

• Used with mortar dyed tomatch the brick, this canincrease the monolithicappearance of the wall.

Mario Botta, Artisan Housing

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The end of thewall

• Masonry bearing wallsfell out of use asbuildings got taller.

• To carry the loads of tallbuildings such as theMonadnock building inChicago, the walls at thebuilding base had to beover six feet thick!…toomuch floor space lost.

Complex walls• Brick masonry is often

used today as a veneer incavity walls.

• A cavity wall puts anairspace behind thebrick…expecting aleak…the water movesthrough the brick, hits thecavity but cannot cross it,so it falls to the cavitybottom, is collected onthrough wall flashing, andis drained out throughweeps in the brick wall

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Copperbeginning

• Here a paper thin sheetof copper flashingcovers the brick ledge,and extends up oneblock above the interiorfloor level.

• This through wallflashing will collect anymoisture coming intothe cavity and weep itto the exterior.

PVC flashing• In multistory

veneer walls,galvanized steelangles oftenhold up thebrick.

• Any interruptionin the cavitymust be flashedand wept to getrid of moisture inthe wall

The contemporary masonrywall

3 courses = 8 inches(one block course)

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String & Storypole• Laying a course of

brick to a specificlevel height requiresa guide.

• Here the mason hasset a stringline aftertransferring thecoursing elevationsfrom a storypoleprepared for thisproject

Bed

• The Mason laysmortar on top of thebricks (and ties)already in place onthe course below.

• This mortar will formthe bed joint.

Furrow

• The mason turns overthe trowel and forms afurrow in the bed joint.

• This pushes mortar tothe outside faces ofthe brick, ensuringenough mortar to slowdown the passage ofwater into the joint.

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Butter & Press

• The mason picks up abrick, butters mortar oneach end (the headjoints) and presses thebrick into the furrowedmortar of the bedjoint…just to the heightof the stringline.

Strike & Tie• With the head joints filled, the brick

pressed into the bedjoint to theheight of the stringline, the masontrims the mortar that squeezed out ofthe back of the head and bed joints,then trims the excess mortar fromthe face joint.

• The excess mortar from the backtrimming often falls into the cavityand can contribute to making amoisture path from the outside of thewall to the inside

Ties

• The brick is held to thewall with the brick tie.

• This tie is adjustable,allowing the mason toslide the tie up or downto meet the bed joint.

Note mortar droppings on tie

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This wall has aproprietary productmade of an expandedmesh of recycledplastic. This mesh issupposed to catchmortar droppings fromthe backside joint trimand prevent the cavityfrom being clogged upwith mortar.(disrupting it’s abilityto prevent waterpenetration)

Cavity cover.

• With the ties in placeand the joints trimmed,the mason will tool (orrod) the face joint toachieve the specifiedjoint profile

• When done for the day,the mason will cover thecavity to preventmoisture fromaccumulating in thecavity