Masonry Magazine December 1995 Page. 31
Structuring the Sunny Face
Structuring the sunny face of the structure during the hot part of the day should be scheduled, if possible.
Masonry Construction
Regardless of climatic conditions, masonry construction should proceed being attentive to the wall design, be it a barrier wall or a cavity wall. Barrier walls must be constructed with full mortar bed and head joints and mortar or grout completely filling any air spaces between adjacent wythes. Cavity walls must be constructed so the cavity between wythes is free of mortar droppings or protrusions.
Flashings must be continuous and weepholes spaced every "x" number of units. Flashings should possess end dams, be lapped with laps sealed, and project outward from the face of the exterior masonry wythe.
Weather conditions should not be allowed to have an effect on the masonry construction. Cold temperature mortars will require less tempering of the masonry mortar; hot weather will require more frequent tempering. It is generally more sensible to provide an adequate working atmosphere than to be concerned with the weather effects on materials and masonry.
Protection of Completed Masonry
All completed masonry should be covered during work stoppages and after the masonry segment is completed. Water entering the top surface of the masonry segment will saturate the wall, cause soluble compounds to be released and show as leachates or efflorescence, and subject the wall to damage if freezing occurs. The covers should remain in good condition till allied trade cover the top surface of the masonry segment.
Weather covers for masonry segments should be selected on basis of historical weather information and weather forecast. During cold and sunny days, clear plastic sheeting allows solar radiation to penetrate the membrane and provide some heat to the masonry. Conversely and on hot and sunny days, black plastic sheeting is preferred, as black surfaces warm and cool faster than white surfaces.
Grouted masonry should receive special attention during cold weather masonry construction. Because grout is contained in the collar joint or cells of units, the wind chill (rate of cooling) effects are lessened. The high water content grouts, however, can undergo disruptive expansion if the grouted masonry is unprotected or heated during the early stages after grouting. Every protective measure should be taken to avoid the freezing of the grout until the water content of the grout is sufficiently low that disruptive expansion will not occur.
Because grouted masonry can couple clay units with concrete masonry units both with an array of absorption characteristics, it's difficult or impossible to predict the period before freezing will occur. Thus, grouted masonry should be overly protected with heat and covers provided. Failure to maintain the grout above freezing can result in disruptive expansion, as evidenced by splitting of the CMU face shell or misalignment of units.
Summary
Both hot and cold weather masonry construction can and should continue during these other than normal weather conditions. The masonry contractor should be allowed to and should modify the masonry construction procedures to compensate for weather effects. The masonry contractor's decisions will be based on equipment already available, possible rentals, and other options available for the production of quality masonry. It should be understood that masonry constructed during both cold and hot weather periods has a greater tendency toward evidencing efflorescence. The appearance of efflorescence signifies less than optimum curing conditions, thus curing and cleansing remedial action may be required.
STICK WITH
CHRISTMAS SEALS.
USE THEM TO FIGHT
LUNG DISEASE.
キ
AMERICAN
LUNG
ASSOCIATION
1-800-LUNG-USA
Space contributed by the publisher as public service
DUR-O
BARRIER
WALL FLASHING
It's fast, easy,
economical...
and it's by
DUR-O-WAL
SELF-SEALING
SELF-HEALING
FULLY ADHERED
AND FLEXIBLE
STAINLESS DRIP
EDGE FLASHING
Dur-O-Barrier Wall Flashing
Installs easily to masonry, concrete, steel, gypsum or wood. It's manufactured with 32 mils (.8mm) of rubberized asphalt and 8 mils (2mm) of high density cross laminated polyethylene film so it resists puncture, abrasion or other damage during installation and even heals itself if slightly damaged.
Dur-O-Barrier installs with greater ease than other wall flashing materials. Corners and dams are formed easily on the job.
Dur-O-Barrier Wall Flashing provides excellent moisture resistance, flexibility and good tensile strength for long term performance and works best with Dur-O-Wal Stainless Drip-Edge Flashing Strips to form a Complete System with a clean, straight appearance.
Available in roll widths of 12", 18", 24" or 36", Dur-O-Barrier is the fast, easy and economical way to install wall flashing.
Other Dur-O-Wal Products...
Not only can Dur-O-Wal supply you with all the other moisture control products you might need, but other materials as well; such as masonry anchors; veneer the assemblies: seismic and restoration products: movement joint and stone anchors.
For more information or a FREE consultation, contact your factory authorized distributor or call toll-free: 1-800-323-0090
즈
DUR-O-WAL, INC.
3115 N. Wilke Road, Suite A
Arlington Heights, IL 60004
(708) 577-6400
FAX: (708) 577-6418
MASONRY-NOVEMBER/DECEMBER, 1995 31