second tects issue 88 How To Spot Distress ln Masonry Structures previous repairs that are indicative bricks at intermittent spacing of previous or possibly, existing which are turned 90 degrees to conditions the normal coursing, used to tie 4.Determine, whenever possible the two wythes of brick together construction method F. Brick masonry facing over metal A. Solid brick masonry wall , gener- stud and gypsum wall ally found in older structures With th is information in color, composition, strength and util- B. Brickmasonryveneerover, and in hand,consider the fol lowing compen- ity, while sharing some basic traits in contact with, concrete masonry dium of common masonry problems construction and destruction. un its (CMU), or structural clay ti Ie and possible causes. Causes will vary The ability of any masonry wall to C. Brick masonry with a Bap or cav- with the type of construction. The withstand deterioration is a function ity between it and the back-up following information is necessarily construction "broad brush" and is not intended to D. Reinforced brick masonry, with replace, but rather to supplement , rebar cast into a grout-filled cavity professional diagnosis of your E. Masonry bonded wall, with building's condition. and in fact, m by sealing INSPECTION POINTS FOR MASONRY BUILDINGS svstem. The usî be found /NIER/OR OF PERIMETER WALLS Water stains around windows, and resolved. peeling or flaking paint on perimeter walls What follows is a two part checklist PARAPET WALLS AND PARAPET CAP Openings in parapet cap to help you evaluate the extent of joints, cracks or holes in the parapet walls distress in masonry buildings, First, ROOF FLASHINC Holes or cracks in the flashing you mustgain an overall impression of WINDOW SEALANT Cracked or open perimeter sealant; broken the building, from the type of building materials used to obvious weak points ntels (These are the or glaring problems that are easily window) discernible, even tothe untrained eye. spalled masonry units The second section of our checklist BUILDING CORNERS Vertical cracks close to each side suggests ways to spot common prob- lems before they become critical. CAINING AN OVERATT IMPRESSION l.Review any existing construction documents 2.Determine the building's age SHELF ANCLES Rusting angles 3.Note the condition and extent of .l volume 7 numbe¡ 2 copyright Hoffmann Architects 9BB I d WATER INTRUSION APPEARANCE Efflorescence, a white, dusty appearance on the brick surface; Areas of abnormal wetness that can be observed after precipitation; Moss growing on masonry surfaces. CAUSES Look for water intrusion at a point above the surface condition o Bond failure at mortar joints . Adhesive failure of sealants . lmproperly struck mortar ¡ Loose or missing mortar . Lack of, or plugged, weep holes . Lack of, or improperly installed, flashing Cracks in window sill BULG¡NG OR OUT.OF.PIUMB WATLS APPEARANCE Perceptible bowing of the masonry veneer in either horizontal or vertical planes CAUSES Vertical Bowing . Failing relieving angles . Laci of soft joints below relieving angles . Wall tie failure o Use of open cet of masonry tl" '"r_ å"rj;,?n expansion joints Surface spalling of concrete in a parking garage . Use of open cell insulation that absorbed water, dislodging masonry through freeze/thaw cycles CRACKS IN MASONRY AT BUILDING CORNERS APPEARANCE ¡ Vertical cracks or dislocation of brick at building corners . Cracks at a regular spacing along building facadðs CAUSES o Discontinuity of relieving angles at all columns and spacing .¿ and deteriorated condition of wall ties in these locations . lnsufficient vertical soft joints Cracked window sealant alr SEEMINCTY RANDOM CRACKS i. APPEARANCE 'lll . Cracks traveling in a combination of vertical and horizontal directions, but always following the mortar joint . Cracks runníng uninterrupted through the mortar and the masonry CAUSES . Uneven settlement r Failure of relieving angles o Horizontal displacement of walls Cracks in parapet cap 2 Of Time and Motion By Walter E. Damuck, A¡A Forget about an airplane flying into long brick wall is expected to grow modate stresses caused by building your building, or earthquakes, or fire, about 0.02% (0.0002), or about 5/64 movement and cyclical volume bombs, tornadoes or war damage. of an inch (2mm)over a period of time. changes without excessive cracking. There's very little that can be done to Thermal growth, on the other hand, is They possess greater adhesive (bond) preclude these extrinsic destructive reversible and can amountto as much strength than cohesive (internal) forces. as 1/B inch (3mm) over a 100 degree strength, thus, if cracks develop, they Out of the baker's dozen of primary Fahrenheit (3BC) temperature differ- will most likely occur within the mor- factors contributing to premature ential. Consideration must be given in tar joint itself rather than at the inter- building decay, only 317o are prod- design and material selection to take face where leakage is more of a prob- ucts of nature: 1) Air, especially the care of this growth and movement. lem. oxygen in iI; 2) Temperature, in ex- Lime-rich mortars, which are softer Understanding the behavior of tremes and fluctuation; 3) Wind, with than cement-rich mortars, will absorb brick, we should also consider the its pressures and suctions; and, 4) some of the growth; but this is not to material mostcommonly used to back Water. The three most important of say that building control joints and it up concrete block. Concrete these are water, water and water. horizontal relieving angles are not block -behaves the same as cast-in- The other 69% of destructive factors required if lime-rich mortars are used, place concrete and precast concrete originate with homo sapiens (man, they are. High lime mortars are slow when made with the cements cur- woman and child, maybe even teen- hardening and remain elastic or flex- rently in use. Today's concrete prod- agers), Sad buttrue. Sad, because the ible and are, therefore, able to accom- ucts do not Brow in use...they shrink. exercise of only a little more The cement in use today is judgement and care can pre- natural, portland or pozzo- vent the more than one billion dollars a year that property owners are paying for human fallibility. The human contri- butions are: 1) Design deficien- cies; 2) Poor materials selec- kiln and finely pulverized. tion; 3) lmproper construction; When mixed with water itcalci- 4) Deferred maintenance (be fies at a rapid rate. lt will never honest, say neglect); 5) Applied efore forces; 6) Weight; 7) Yibra- then, tions; B) Pollution; and, 9) Vandalism. åí:3j similating the water raises its BRICK temperature, causing what is known as the heat of calcifica- tr t( Let's first consider brick, one Tt- tion. The cement powder has of the basic masonry materials rr become so hungry, once united that includes clay tile, adobe r r rr with water it takes years to give and terra cotta. ln modern F T fr- it all up. I I fr manufacturing, brick ware r rf- What this means is that con- shrinks about B% in size in the I' ¡" Í' crete and concrete products are r- rt kiln. Assoon as it ls put into use, t- l-r' rin the brick is trying very hard, by I Fr ¡t is T rr absorbing moisture, to regain rt- some of the volume it lost. ìr liï; Brick continues to grow in size it after being laid into a wall. This shrink? About 4-1/2 times as growth is irreversible! A30foot much as brick grows, or, ulti- I passed." "The building waved everytime Continued on next page Craphic by Richard Kadlubowski 3 f d Continued from previous page grade and one floor above grade. is seldom properly moistened before mately, somewhere around 11/32- Acceleration was experienced on the erection to reduce suction in hot inch (9mm) over a 3O-foot length. uppermost floors, masonry in the ele- weather, and, the mortar is invariably Thermal movement, on the other vator hoistways and stair towers was retempered, even after initial set of hand, is nearly static... just a shade spalling, and joints were opening up. the cement has started. Ergo, un- greater than 1/1 ,000 that of brick, or fonded, friable, and leaky joints re- 0.165 mil (o.000165 inch) su lt. (0.004mm) in 3O-feet. Recent con- crete-framed projects have been "Deferred DEFERRED stal led duri ng curtain wal I instal lation møintenønce MAINTENANCE because hundreds of prefabricated panels did not fit. Detailed connec- produces, , ,leøks, lf you care to have the very best, tions did not line up with the corre- deferred maintenance should not be rust ønd dry rot." in your vocabulary. Deferred mainte- nance produces three building No shear walls had been incorporated scourges: leaks, rust and dry rot. into the construction, and the dis- Very often, a tradesman is called in placement at the top of the tower was more than 50% of what it should have been. The building waved at me every time I passed. The seven-story building was con- crete-framed on bearing block walls and brick veneered, actions in dia- sponding slab connections because metr the slabs had lowered as a result of was concrete shrinkage. but, pair. prov THE HAND OF MAN growth and to compensate for the concrete block shrinkage. Time has an aging influence, our buildings are in continuous motion, the materials we use have their weak- nesses, and Mother Nature keeps working against us. All of these factors expert to properly repoi nt the parapet. must be applied in developing an Both sides of masonry parapet walls etiology for building skin problems, must be permitted to breathe! being always mindful that some of Remedial recommendations for them are imputable to the building any building require extensive re- skeleton.