- Practical advice
- The laying of the banners
- Zinc welding
- Infiltration of water and dirt
- Nest the edge strips
- Trace the landmarks
- Drill the fixing holes
- Fix the covered
- Cover angles
- Weld the fittings
Uncovered masonry inevitably ends up undergoing water infiltration. Whether it is absent or degraded, it is urgent to think about their tightness to avoid heavy damage.
● Working at the edge of the roof is not safe! Wear a standard (and perfect) shoulder harness securely attached to a fixed point, such as a chimney, with the shortest nylon rope possible.
● Be careful, too hot a fault, left too long in the same place, may pierce the zinc.
This roof-terrace cornice consists of several rows of bricks shifted forward, forming a genoise. At the rear, the vertical fallout (or acroterium) is lined with a waterproof asphalt aluminum. But the last row of bricks has not been finished. To remedy this, a zinc bib with rolled edge, also called edge band or sewer strip, will be placed on the edge of the cornice. Overflowing outside a few centimeters, it will create a break of the film of water, thus avoiding the flows on the walls.
The laying of the banners
The edge strip consists of zinc sheets 2 m long and 95 mm wide. An ideal dimension, since the bricks of the cornice measure 65 mm. The outer edge will be 30 mm.
● Drill zinc every 60 cm, position the strips by adjusting them to get a regular overflow and mark the needle brick through the metal. Then enlarge the impressions with the Ø 6 mm concrete wick. After pegging, fix them by Ø 5-20 mm screws with washers, all in stainless steel. Continue with the following strips by interleaving the two rolled edges by a few centimeters.
● At the corner of the terrace, make a 45° cut of the two sheets to be connected after tracing to the protractor. The flat parts are easy to cut with sheet metal shears, but a hacksaw is required for the rolled edge. Allow a lap of about one centimeter to facilitate the welding of the two pieces.
The zinc strips must be welded at each fitting and at the corners, with the tin-lead rod at 33% tin and the zinc-plated gas iron. Thoroughly clean the junction of both bands with steel wool or fine emery cloth. Apply with a brush a special flux flux on the joint. Available commercially, you can also prepare it by dissolving a few pieces of zinc in hydrochloric acid. This gives you a less aggressive blend than pure acid.
● Heat the zinc iron until the tip turns a "pigeon throat" color, then turn off the gas. Rub the tip on the ammonia stone while applying the solder rod. It melts and adheres to the breakdown: it is tinning.
● Place the tip on the joint between two strips by pressing the end of the solder rod over the hot metal. Back off simultaneously to form a regular bead. Smooth the beads as needed with the iron, and allow to cool before rinsing with a damp cloth.
A joint must be made between the zinc roof and the top of the cornice. Unscrew about 1 cm from the previously installed fixing screws. Lift the cover and extrude a continuous bead of polyurethane putty into a cartridge.
● Work in strips of 2 m and immediately tighten the screws after lightly coating the underside of the washers. Under pressure, the putty spreads and overflows. Smooth immediately on a finger dipped in soapy water.
Infiltration of water and dirt
The cornice of the terrace consists of several rows of staggered bricks. Over the years, the lack of cover has caused water infiltration and dirt on the coating.
Nest the edge strips
The roof will be made by means of zinc edge strips with an inner flat edge and a rolled edge. At the junction of two strips, the rolled edges fit one into the other.
Trace the landmarks
At each end of a strip, mark a mark 65 mm from the flat edge, giving an outside edge of 30 mm. Make the two landmarks coincide with the ridge of the cornice.
Drill the fixing holes
Trace on the zinc the location of the fixing holes, every 600 mm and 30 mm from the right edge. Mark them with the punch and drill the masonry with a Ø 6 mm concrete drill bit.
Fix the covered
Insert dowels Ø 6 mm into the holes, replace the cover and fix it temporarily with stainless steel screws Ø 5 - 20 mm by inserting stainless washers under the screw heads.
For each corner, trace the sections at 45°. Leave a welding tab on the bottom strip. The cuts are made by shears for the flat parts and by hacksaw.
Weld the fittings
The fittings are welded to the gas zinc iron. The filler metal is a tin-lead rod with 33% tin. A specific stripper must be applied to the joint before welding.
For sealing, unscrew the screws 1 cm. Inject with polyurethane putty and tighten quickly after mastic coating the underside of the washers. Smooth on the wet finger.