Copper Flashings - A Manual - 1925 - Page 45
further attention, because the elements will not rust the bronze and damage the work.
Attention is called to the following paragraphs from the Standard Specification for the Manufacture, Furnishing and Setting of Terra Cotta, published by the National Terra Cotta Society, September, 1923.
PREPARATION FOR FLASHING
14. — Where so shown the washes of all projecting cornices and other exposed horizontal surfaces shall have provision made for flashing. All surfaces where the wash pitches inward toward the structure and stops against superimposed work: all balcony floors, and all gutter grades shall have provision made for flashing.
15. — Raggles shall be provided to receive gutter linings and flashings when the joints can not be used for the purpose. Raggles shall be not less than ¾ inches deep.
SUGGESTIONS FOR COROLLARY CLAUSES
87. — In the case of parapet walls specifications should state that flashing if used shall be carried through the wall, or if flashing be not used the back of the parapet wall shall be damp-proofed and the water-proofing carried through the wall.
88-2. — In the specifications for sheet metal work there should be included a clause similar in purport to the following:
"The washes on all cornices and other exposed surfaces, where shown or specified, shall be covered with (.......) which shall be turned up against vertical surfaces (cap flashed) and cemented into the raggles provided for the purpose in the Terra Cotta"
FLASHINGS FOR STONE WORK
One of the chief considerations in using copper with building stone is the avoidance of stains. When copper is applied directly to light-colored building stone or marble, sweating or condensation on the underside sometimes causes discoloration. To avoid this black waterproof paper (not tar felt) should be laid underneath the copper, so as to prevent direct contact between metal and stone.
It is also important to design the work so that the wash from the metal does not flow down over the face of the stone work. This, indeed, applies to any type of roof, for the dirt which collects on the roof will make any such wash objectionable.
This can be overcome by detailing the stone work to drain inward except the small portion beyond the outside reglet.
Good practice in stone work, with parapet and other walls faced with stone, calls for reglets rather than for step flashings in the joints. The reglet is cut straight or at an angle across the stone as the occasion may demand.
Many experienced stone setters consider lead wedges and lime mortar the best method of filling the reglet. The objection to this is the necessity for frequent repointing. Lead wool or molten lead do away with this objection.
Reference to Figs. 53 to 58 and to "Caulking," page 54, will make these points clear.
FLASHINGS FOR CLAY AND CONCRETE ROOF TILE
Roof tile are made of terra cotta and of concrete in a variety of designs. Terra-cotta tile has been in use for centuries. Recently concrete roof tile similar to terra-cotta tile has been put on the market with marked success. It is low in cost, easy to apply and of pleasing appearance.
Tile roofs require special treatment at the flashing points. Although the principles involved are fundamentally the same as other roofing materials, because of the shape and design of the tile, flashings for them must be of a special nature. Flashings are generally made of larger sheets than with ordinary roofing. This is because of the necessity of covering the joints near the flashing points and also conforming to the irregularity of the construction.
The use of 18-ounce copper is recommended for roof tile flashing. Its thickness helps materially in keeping it in position over the tile by giving it stiffness.
The principal considerations for flashings for roof tile are:
1. To use sufficient copper to cover the joints at the flashing points.
2. To apply the copper loosely and in such a manner that the heavy tile will not hold it too tightly or cut it.
3. To do as little fastening as is possible. The sheets are held in place by the weight of the tile. These points are clearly shown in the drawings, Figs. 47 to 52.
COPPER OVER CONCRETE
When copper is used over concrete the surface should be made smooth by a wash of neat cement. Elastic cement is sometimes used for this purpose.
Cinder concrete should not be used in contact with copper. Where copper is used in this type of construction the concrete should be painted with a heavy coating of asphalt paint before the copper is applied.
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