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I Chimney Flashi
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CHIMNEY FLASHING BEGINSAT LOWEST POINTTypically, the first piece of flashingto be installed on a chimney is thelowest piece, the apron, or base,flashing. Folded step flashing thenis installed along the side of thechimney, one piece for eachcourse of shingles.
Folded
Roofingoverlaps stepflashing.
Corners of apronflashing mustbe solderedor sealed withroof cement.
CRICKET BRIDGES THE VALLEYBETWEEN CHIMNEY AND ROOFIf the chimney comes throughthe roof below the ridgeline,a soldered sheet-metal cricketcan be installed on the uphill sideof the chimney. The valley flangeon the cricket is covered by theroofing. At the corner of thechimney, the flange wraps aroundand over the folded step flashing.
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Valley flange
miniature gable roof on the upslope side ofthe chimney that diverts water around thechimney. Some crickets are big enough actu-ally to be shingled, but most are coveredwith a metal skin bent and soldered to fitthe slope of the roof. Ametal cricket is partvalley flashing; part step flashing, and partmetal roof.
The last step, whether a chimney is atthe ridge or downslope, is the installationof counterflashing (see the drawingsabove). Counterflashing overlaps all thelower flashing pieces, including the apron
COUNTERFLASHING IS WOVENINTO MASONRYThe lower flashings on all foursides of the chimney are coveredwith counterflashing. The upperedge of the counterflashing isbent at a right angle and insertedabout an inch into the mortarjoints between the brick or stoneof the chimney.
Counterflashing
or aprons, the step flashings along the side,and the cricket, if there is one. The topedge of the counterflashing is bent at aright angle and let into successive mortarjoints in the chimney.
For a stone chimney, the irregularity ofthe material makes it tough to let in the stepflashing neatly. To provide straight joints forstep flashing, a mason can substitute brickfor stone at the roofline. Brick is hidden inthe attic space and concealed from the out-side by step flashing.
Apron, or base,flashing overlapsroofing at least 4 in.
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Courtesy BEST MATERIALS LLCPh: 1-800-474-7570, 1-602-272-8128 Fax: 1-602-272-8014Email: [email protected] www.bestmaterials.com
