The blocks have interior open cores as mentioned above. In both cases the top of parapet walls are sealed from ventilating interior trapped moisture. It’s ideal in the installation of the coping cover to design an avenue of ventilation underneath the covers. This system of ventilating will assist the evaporation of moisture that can get trapped in the masonry’s interiors. Parapets are exterior walls extending above the roof plane that are commonly capped with concrete, metal, stone, clay tiles, or terra cotta covers. With block masonry, parapets are typically capped with a coping stone, concrete, or metal. Some have flashing between the coping and masonry, and others are without. Above this horizontal flashing plane, there should be weep openings installed on the vertical mortar joints above the drip every 16 inches or 24 inches. The most common type of weeping systems are rope, louvered vents, plastic tubes, cellular vents, and masonry weep-holes. Weep openings are drainage avenues in the face of the masonry veneer walls and are installed to facilitate exiting water that has penetrated the interiors of masonry walls. This design forces rainstorm water away from the façade and prevents water from penetrating the masonry below. Stainless steel flashing sheets are installed under the membrane and extended ¼ inch beyond the wall and turned bent down at 45 degrees to form a drip. End-dams should be installed before flashing. The flashing on lintel’s ends should be terminated with end-dams ( see sketch 3, End-Dam Detail). The top interior of the membrane should fold back into the backup course joint and turned in ( see sketch 1, Lintel Through-Wall Flashing) or a termination bar is to be installed to the flashing and fastened ( see sketch 2, Lintel Through-Wall Flashing w/Termination Bar) to backup wall. Above lintels, a composite or rubber membrane is installed above and along the steel angle and rises 4 to 6 inches above the upper edge of the steel angle. Typically, metal, a composite membrane, and rubber are the three types of materials used for creating an impermeable water barrier and drainage system throughout masonry walls. ![]() In addition to the block’s composition, there are flashing considerations that might be lacking in the construction of a building. Four Causes of Water Leaks on Split-Face Block Buildings creeping cracks), which can lead to water leakage through the void’s units during rainstorms. This makes the block susceptible to developing hairline cracks (i.e. The average curing period for concrete is between 21 to 28 days. ![]() Shortly after the manufacture’s completion, most blocks are delivered to the jobsite and assembled to create walls while the curing is still in progress. Creep is the deformation of concrete constructions under sustained load.Ī block typically cures for 16-24 hours at high humidity and at an average temperature of approximately 100 degrees Fahrenheit in the manufacturing process. deformation) occurs in concrete masonry walls after bearing the load of the wall assembly. ![]() Ratio of water to Portland cement (higher water, more permeability)Ĭompaction ratio at manufacturer’s plants (if not sufficient, the pores are larger) Manufacturer’s specifications requirementsįabrication materials available in the region of said manufacturer There are several reasons as to the degree of porosity of a block, they are as follows: As mentioned above, the hollow-core blocks are lighter to handle, easier to install, and are the majority used in exterior construction. These cores can be one or a few cell openings based on the construction requirements and manufacturer specifications. On average, the cores are greater than 25% of the gross surface. The most common blocks are the hollow, concrete units that contain voids (or cores) in the interior of the block which help reduce weight and aid installation. The lightweight blocks are created by substituting the gravel and sand with clay, shale, or slate. The typical mixture contains powdered Portland cement, gravel, sand, and water.
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