Masonry Magazine November 2002 Page. 19
Tips and Guidelines for Designers
Moisture Detailing-Due to the imperviousness of the ceramic finish, glazed brick walls should be designed to drain all water that enters the wall system. This water may have its source in wind driven rain or condensation of water vapor. It is recommended, for glazed brick exterior walls, that a vented drainage type wall system be designed, detailed and constructed. This will accommodate the proper flow of collected water within the wall's cross-section.
Two common examples of drainage walls include the cavity and veneer designs utilizing a minimum two-inch cavity between wythes. In either design, flashings and weepholes need be provided at the wall base, under sills, over lintels and relief angles, and under masonry or stone caps and copings. Flashings need to be continuous around the building perimeter at the wall base, relief angles and copings. Isolated flashings, such as windowsills and lintel angles, should be treated with end dams.
Weepholes should be spaced at 24-inches on center in head joints at the elevation of the flashings. Should a rope wick be used as the weephole material, an opening should be provided in the course above. This opening could be a vent or tube insert that should be spaced at 24-inches on center. At the top of a wall expanse, vent inserts should be incorporated to allow air circulation in the drainage space. These vents should be located a course or two below the next flashing location and spaced between 24- and 48-inches on center depending on the interior humidity in the structure.
Movement Detailing-Brick masonry walls move with changes in temperature and moisture content. Wall detailing for the drainage-type walls utilizing a glazed brick facing wythe needs to incorporate room for brick's growth. These joints, placed vertical and horizontal, break the wall into panels. The panel size should be limited to a length of 25 feet to ensure stress levels within the masonry strength.
Panel heights will vary with the building and wall design; however, they should be placed as soft-joints under relief angles. Additional joints, vertical and horizontal, should be utilized in the building parapets to limit panel lengths to 15 feet and isolate the cap or coping from the facing wythe.
The building geometry will also indicate locations for vertical expansion joints in glazed brick walls. These areas include:
CUTTING GLAZED BRICKS
When it comes to specialized units such as glazed bricks, is there a right way and, more important, a wrong way to cut and trim them? These units are obviously more expensive than common brick and need to be treated in a way that will prevent unnecessary waste and scrappage. Careful handling, storage and movement will help but somewhere along the way, some of those bricks will have to be cut. How you do that and what tools you use can make a difference in your eventual profit on the job.
Cliff Maddock, president of World Diamond Source, Pompano Beach, Fla., notes that most glazed brick are on the hard side of the soft-hard curve. "But, then again, it probably depends on the manufacturer," he admits. "If one company is making glazed brick in New York and another is making glazed brick in Florida, probably one's going to be harder or softer than the other one due to the climate and to aggregates used in different areas."
He adds, "I explain to the salesmen, 'It's your job to get the right blade for this customer's application.' Many customers will say they're looking for blade life and are not worried about chippage. For blade life, we recommend a segmented blade."
Moving from blade life to chipping, Maddock explains, "if you looking for fast, clean cuts with no chippage, the first thing I would not recommend is a regular segmented blade, I would recommend either a segmented turbo or a turbo, instead. The segmented turbo and turbo cut a lot faster and cleaner, and they're going to chip a lot less on any material, no matter what you're cutting, than a regular segmented blade.
"A turbo blade is going to cut a little cleaner than a segmented turbo, but you're going to forfeit a bit of blade life. A smooth, continuous-rim blade ultimately would give you a perfect, chip-free cut, but you'd sit there for 15, 20 minutes cutting each brick."
What's the difference in blade design? "On each segment of a segmented turbo blade, there is a turbo ridge every eighth of an inch, which gives it the fast, clean cuts. The turbo blade is a continuous rim blade, no 'keyholes' creating segments, but it has the same ridges along the face at the edge. A turbo blade's going to cut faster than a segmented turbo, and it's going to give you minimum chippage."
Once you have the blade type determined, the bonding comes next. Hard bricks require "soft" bonding and vice versa. Cutting limestone or green concrete? The hard bond blade is for you. Working with granite, pavers or refractory firebricks? Then opt for the softer bonds.
Once you have the blade, how do you make the cut to minimize chipping? Steve Mills, vice president of Quality Diamond Tools, Lake Worth, Fla., admonishes masons to be sure to cut wet. "Cutting it wet prolongs the life of the blade."
He offers another trick to increasing blade life and improving the cut. "Some ceramic bricks contain an iron pigment or iron spot and when you are cutting those bricks, the diamonds glaze up from the ceramic glaze on the product. So, in order to clean the blade, take a paver or some concrete and run it through the saw. That cleans off the diamonds and then you can go back to cutting, Glazing like that on the blade really gums things up."
To reduce waste, check how the brick is laid on the saw, too. Maddock says, "The bottom of the cut is going to be the clean part of the cut. If you want the face of the brick to have the cleanest cut, I would flip the brick over and cut it face down because the bottom of the cut is going to be the cleanest part of the cut."
Mills adds one final reminder. "As far as eliminating waste, it's really up to the installer to lay things out so you're not going to have much waste, to start the job off where he's minimizing his cuts. Careful planning can add more life to the blade and prevent waste by simply cutting back on the number of cuts that have to be made.