Successful Balcony Construction with New Technology
By Joseph Joy
As appeared in Stone World
The installation of stone in an exterior application (balconies in particular) can be a complicated process. The installation usually requires a variety of trades and steps to produce a finished product. Typically, a sloping screed is first applied. Then the roofers apply flashing and a waterproofing membrane. The contractor sets the stones, and yet another trade installs the gutter system. This multi-trade, multi-step process can discourage owners and designers from becoming involved in such a project. Stone installers can be equally discouraged, wary of being the last of many tradesmen on the job. New products and techniques eliminates the need for the various trade disciplines by incorporating the above steps so that they can be easily achieved by the stone contractor. For renovations, the existing surface assembly can generally remain, provided it is sufficiently sloped and load-bearing.
Fundamental to successful balcony construction is the incorporation of a waterproofing layer. This layer prevents moisture from penetrating the substrate (typically concrete) and helps to maintain the integrity of the substrate. Concrete, when exposed to moisture for prolonged periods of time, can deteriorate and become structurally unsafe. The pH level of fresh concrete is 12.5. When that level drops below 9.5, the reinforcing steel rusts and expands, causing the concrete to spall. By installing stone over the waterproofing layer, you achieve both a protective layer for the waterproofing and an attractive wear surface. Stone, when properly installed, are the ideal surface coverings for any balcony.
Construction begins with special edging profile. This edging profile, for balconies and terraces, is specifically designed for a flush connection to the waterproofing layer. The perforated leg of the profile is positioned over the structural slab. The edging profile features a ribbed bonding flange for applying a narrow seaming band, which seals the joint between the waterproofing membrane and the edging’s flange. The special edging profile features a drip lip for a gutter system.
A different profile is available and should be used if a sloping screed is necessary. This version has a greater depth to allow for the sloping screed, and features a small guide bar on the vertical section of the profile to be used as a screeding guide. This creates an allowance for the flush connection of waterproofing membrane. When using other waterproofing materials, such as a bituminous material, the screed is leveled to the upper edge of the profile. The waterproofing material is then applied over the bonding flange.
Once the edging has been installed, the next step is to install the waterproofing membrane. The ideal material to use in this application would be an uncoupling, supporting, and waterproofing membrane which not only provides a moisture barrier but also prevents damage from movement. In addition, this sheet applied material can be used over a variety of substrates including green concrete. Any substrate, however, should be even and load-bearing.
The material is a corrugated polyethylene sheet with a support webbing laminated to its underside. The corrugated ribs are cut back in a dove-tail configuration, providing a mechanical bond to the tile. The support webbing on the underside provides a mechanical bond to the substrate. The side edges of the sheet are flat and allow for overlapping.
The uncoupling characteristic of the membrane prevents stresses in the substrate (due to thermal deformation, shrinkage, settling, and deflection) from being transmitted to the tile surface. In addition, the special ribbed structure provides air channels between the membrane and the substrate, permitting ventilation of the substrate.
Installation: 1. Apply the appropriate adhesive (generally an acrylic/latex fortified mortar) to the substrate using a 1/4" x 1/4", square-notch trowel. When applying the membrane over a sloped substrate, begin at the lowest point, with the corrugated ribs running in the direction of the incline. 2. Roll the matting into the thin-set mortar in such a way that the support webbing is firmly embedded in the adhesive without filling the channels on the underside of the matting. 3. To install the tile on the membrane, match the trowel size and mortar to the type and format of the tile.
For seaming the membrane, apply a dry-set mortar and solidly adhere the 12.5-cm-wide seaming band. For floor/wall connections, adhere the seaming band in the appropriate width. The seaming band is made of soft polyethylene that is covered on both sides with a fleece webbing. The fleece provides a mechanical bond to the tile adhesive. It is pliable, stretchable, and rot-resistant and has a limited crack-bridging ability.
Firmly embed the seaming band in the adhesive in such a way that it adheres to the membrane on the floor and directly to the wall substrate. This process is repeated for the connection between the membrane and edging profile. It is important to achieve full coverage.
Prior to installing the tiles, a soft zone should be incorporated at the inside corners. A pre-made corner movement profile made of recycled rigid PVC and soft CPE effectively absorbs movements at inside wall corners and floor-wall transitions. The 3/16" (5 mm)-wide movement zone becomes the visible surface, creating a uniform and discrete joint appearance that matches common joint widths. In addition, the pocket of the profile hides the cut tile edges.
Once the tiles have been installed, the gutter system is suspended from the edging profiles. The snap-in components are constructed of UV/color-stable PVC and are available in the same colors as the edging profiles. The gutter system includes everything required, including piping, elbows, and down spouts.
Using new technology and techniques is a completely integrated approach to successful balcony construction. The advantage to the owner is that it becomes a single-source project. The installation can be completed quickly and economically by eliminating the coordination of trades and subsequent waiting times. The benefit to the tile installer is project control from start to finish and a greater share of the work.
New products and techniques eliminates the need for the various trade disciplines in balcony construction. Now the stone contractor can apply the flashing, waterproofing, gutter and the tiles. The installer achieves full project control and the owner benefits from single-source responsibility.
For seaming the membrane, apply a dry-set mortar and solidly adhere the 12.5-cm-wide seaming band. The seaming band is made of soft polyethylene that is covered on both sides with a fleece webbing. The fleece provides a mechanical bond to the tile adhesive. It is pliable, stretchable, and rot-resistant and has a limited crack-bridging ability. It is important to achieve full coverage.
For floor/wall connections, adhere the seaming band in the appropriate width. Firmly embed the seaming band in the adhesive in such a way that it adheres to the membrane on the floor and directly to the wall substrate. This process is repeated for the connection between the membrane and edging profile. Prior to installing the tiles, a soft zone should be incorporated at the inside corners. A pre-made corner movement profile made of recycled rigid PVC and soft CPE effectively absorbs movements at inside wall corners and floor-wall transitions.
