Tile Balcony Retrofits

In multifamily housing, it is not uncommon for developers and builders to deliver units to the home buyer with very basic finishes, allowing the new owner to select and install their own materials after the sale is complete. Exterior balconies and decks are often finished with bare concrete or a roofing membrane. To further complicate matters, these outdoor areas are often designed as level, with no accommodation for drainage, and it becomes the problem of the owner, the design professional, and the tile contractor to retrofit a finish that will be as functional as it is beautiful. ?

Unfinished concrete balcony        

In the absence of a sloped balcony deck, an unbonded, reinforced mortar bed may be used to provide slope for a new tile finish, but only if the existing conditions can accommodate such a solution. Prior to installation, the critical first step is a thorough assessment of existing conditions. Several questions must be addressed to determine whether a sloped mortar bed might be used successfully. ?

Where will the water drain? The existing size and configuration of the balcony or terrace will help to answer this question. If the size is small and the configuration has little depth relative to length, a simple solution may be to provide slope in one direction only, away from the building, and let water drain off the balcony edge, either onto the ground or into a facia-mounted gutter. If the terrace has significant depth, it may be necessary to slope in more than one direction to keep the mortar bed’s thickness manageable. In long and shallow configurations, the water may be directed through scuppers into downspouts. For vast areas of roof to be tiled, a system of roof drains will probably be used. In any case, if the tile contractor is providing slope, drainage is the first and most basic question.??

Balcony before tile retrofit        

Is there sufficient height between the door threshold and finish balcony? For standard slopes of 1/4 in. per foot, there must be an adequate difference in elevation between the high point of the door threshold and the low point of the finish tile. Unbonded mortar beds should not taper to less than 1 1/2 inches at their low point due to embedment requirements for the wire reinforcement mesh. Working from the minimum thickness of the mortar bed at the low point and considering the thickness of the tile and adhesive mortar, it is possible to assess whether there is enough vertical space to provide sufficient slope. ?

What if we don’t have the height? If there isn’t enough vertical distance between the door threshold and the balcony edge or drain to maintain 1/4 in. per foot slope, there might be a work-around. Perhaps the owner may accept less than 1/4 in. per foot slope. Perhaps the mortar bed can be bonded instead of unbonded, and therefore taper to 3/4 in. instead of 1 1/2 in at the low point. Maybe the slope is provided in two directions instead of one direction. Whatever the solution, the tile contractor should seek approval of the design professional if there is one, or the owner if there is no design professional on the project, and of course comply with all building codes and manufacturer requirements. ?

How does the tile assembly tie in with the roofing system? Roofs are complex assemblies of the building enclosure, and the tile contractor should not remove roofing materials or make alterations to roofing components like flashing or membranes to accommodate the tile assembly. Roof terminations at adjoining walls, parapets, and perimeters are delicate details, and disturbing these conditions could void the owner’s roof warranty. Where possible, install the tile assembly around the fixed elements of the roof system. ?

How will the tile assembly be waterproofed? The primary waterproofing membrane should have been installed by the roofing contractor prior to any tile work, and it should remain protected at all times. Secondary waterproofing installed by the tile contactor on the sloped mortar bed will prevent water from penetrating into the assembly. This is especially important if there is occupied space below the roof or terrace. ?

Balcony after tile retrofit        

How will the tile assembly move? Tile on balconies and terraces has potential for a great amount of movement, especially in an unbonded system. Exterior tile assemblies can have significant exposure to extreme temperatures as well as moisture, therefore it is critical that movement not be restrained. Provide perimeter expansion joints all around the tile assembly, as well as in the field of the tile, per the architectural plans and ANSI and TCNA recommendations. Protect the sealant at the perimeter expansion joint with counterflashing where the balcony edge meets the wall. ?

How will the tile be terminated at the balcony edge??Adding a mud-set tile assembly several inches thick will impact the appearance on the exposed balcony edge. Work with the design professional to develop an edge detail that protects the front face of the mortar bed and setting material, and that enhances the appearance of the balcony. ?

We are using outdoor space like balconies and roof terraces now more than ever, so it is natural to want to retrofit these spaces with finishes like tile that will enhance our enjoyment of them. Retrofitting tile on existing level balconies requires a solid understanding of fundamentals like drainage, minimum and maximum thicknesses of mortar beds, slope, and interface between tile and roofing materials. With thorough existing condition assessment, thoughtful design, and a qualified tile contractor, many level balconies can successfully benefit from tile retrofits. ?

Note: This article is adapted from an article by the same author published in 093000 Tile Contractor, the publication of the Tile Contractors' Association of America, Summer 2022 edition. Thanks to John Cox of Cox Tile for suggesting this topic and for sharing his experience and insights on retrofitting balconies with tile.