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ROOFING, WALLS AND BALCONIES

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This article will discuss three components of a building: the roofing, the walls, and the balconies.

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Balcony Display

At the top of the wall, behind the balcony, you will see green membrane material, commonly referred to as flashing. This waterproofing membrane is attached to walls, lintels, and sills in areas vulnerable to water penetration. Its purpose is to divert water to the exterior, rather then allowing it to enter the interior of the building.

Just below the flashing, you will notice a high-performance door designed to keep air and water out during severe weather. The door shown is a heavy-duty, thermally insulated balcony door constructed with two layers of insulated tempered glass.

At the base of the door, you will see a copper flashing system, which aids in diverting any water that might otherwise enter the interior of the building. To the left of the door, you can see an air conditioning sleeve. The sleeve is supported by a lintel at its top and is surrounded by a weather-proofing membrane.

The air conditioning sleeve is made of a non-corrosive material that is pitched to the exterior to divert condensation from the interior of the building and from the air conditioning unit.

The balcony may incorporate an optional, brass-covered drain. This type of drain is often found on balcony decks that are either surrounded by a curb or have solid parapet walls. The decks of balconies with drains must be pitched toward the drain to prevent pooling or water buildup that could overflow into the interior of the building. To ensure proper functioning of the drain, it is important to keep the drain cover clean and unclogged at all times.

Balconies

Balconies designed with open rail systems and no curb most often will not contain a drain. In this case, the deck will be pitched to the outside perimeter of the deck to ensure proper dispersal of water away from the interior wall. A waterproof coating is applied to the balcony deck, curb, facade, and soffit. Different types of coatings are used at the different locations in accordance with job-specific applications.

The balcony deck has a high-performance membrane system and uses a non-skid application with 100% waterproofing capabilities. The curb area uses a breathable membrane from the railing to the front area of the curb or facade.

Although the soffit area appears to be solid concrete, it is actually a highly breathable membrane. This type of coating is used to allow any trapped moisture to escape. All of the discussed systems come with either a five or a ten-year warranty.

Balcony rails must extend upward a minimum of 42 inches from the deck surface, with rail spacing not exceeding 5 inches according to some city codes. Be sure to check to ensure compliance with any state or city regulations. There are two different mounting options for balcony rails. The first type is a surface-mounted plate with four galvanized stainless steel expansion bolts or epoxy-anchored bolts. The second type involves the posts being mounted in a sleeve or an epoxy-filled void left in the forming of the concrete. In both applications, the void where the post and the concrete meet must be caulked to prevent water penetration.

Building concrete is reinforced with steel bars, or rebar, when pored. These reinforced steel bars are properly spaced and tied together, then placed on wood forms before the concrete is poured over and around them. All rebar must be covered by a recommended minimum of two inches of concrete. The purpose of this is to prevent rebar corrosion, which leads to a loss in concrete integrity. An example of a typical balcony deck support is the solid brick wall, a style used in older, pre-World War II construction.

Walls and Facades

The same lintel detail above the window and a flashing installation similar to that in the balcony may be used. At the brick course above the lintel, there are three weep tubes. These weep tubes allow moisture to exit the cavity between the concrete wall and the brick facade.

The cavity-type wall construction represents current construction techniques.

On the cinder block inner course, you will see a white vapor/ air barrier wrap. This barrier is used to aid in reducing moisture penetration and drafts through the concrete walls to the building interior.

Holding together the inner and outer masonry and cinderblock walls are straps and a metal truss system.

Scanning down the wall, notice the green mesh, just above the copper, between the red exterior facade brick and the interior cinderblock. This material is known as a mortar net. This is used to protect the cavity from becoming clogged with mortar during installation of the brick facade. In addition, weeps are installed on the facade brick exterior directly above the wall flashing. The weeps allow moisture that might enter the wall to escape to the exterior.

The through-wall flashing consists of two pieces of 20-ounce copper. This construction technique is used to facilitate future replacement or repair of the flashing.

Double-hung, thermally insulated windows tilt in for ease of cleaning and are designed to prevent air and water entry during severe storms. Thermal-pane windows are made up of two glass panes separated by a gas-filled space.

The exterior of the window sill below the window is flashed in a manner similar to the lintel previously discussed. It also has weep tubes installed under the stone sill to allow moisture to escape to the exterior. The underside of the sill has a drip edge that prevents water migration into the building. The drip edge appears as a V in the bottom edge.

On the left side there should be a parapet wall topped with a coping stone and a terrace railing. The terrace railing is similar to the balcony railing and must conform to the same regulations. In addition, there is a coping cover over the coping stone. This cover prevents water entry on older stone systems.

The parapet rail is installed in a metal sleeve that is built as part of the parapet wall. The rail posts are set in epoxy, and caulking is applied around the posts to the stone aluminum cover.

Roof Area

On terraces or rooftops in which pavers are installed as the wearing walking surface, a two-tier drain is required. The high-density, pre-formed, 2-inch thick pavers are set on top of high-density plastic pedestals specifically designed for this use. Where pavers are used, it is highly recommended that flashing, such as a copper kick plate, be installed along the perimeter. Underneath the pedestal, a protective roofing board is used to support the pavers.

A built up roofing system section is comprised of a two-ply vapor barrier set on top of the structural deck. This is then topped by an insulation layer, with three to four additional layers of roofing set on top. As you can imagine, there are many different types of roofing systems. The design is highly dependent upon the application and any budget allowances. Before replacing any roofing system, it is imperative that the existing system be evaluated for moisture content and the presence of asbestos in the materials used. Design professionals should be consulted before moving forward with a repair or roof replacement. A circular roof drain may be installed on this type of roofing surface with a lead bend and a gravel-retainer ring. It is critical that the details around drains and other roof penetrations are properly and carefully addressed to ensure a penetration-free system.

An aluminum sheathing is commonly placed on interior parapet walls and bulkheads. This is used to eliminate water penetration in these areas.

Please remember that when repairs or replacements for either balcony or roofing sections are required, it is imperative to retain competent design professionals and manufacturer-certified contractors. Permits may be required, and it is important that extended warranties for all aspects be obtained to protect the investment of the work being performed. Most roofing warranties require that building personnel perform and keep logs of regular inspections.