How to install mirror: fastening an un-framed mirror on a wall.
Installing mirrors can be tricky if you do not consider the potential complications. Typical complications would be attempting to install mirror on an uneven wall, walls with loose plaster, and walls lined with wallpaper, paneling and other surface treatments.
For a quick reference to each:
Walls with wallpaper, paneling and other surface treatments: Mastic will not firmly adhere to several wall treatments and should not be used in these applications. Clips and/or mirror channel should be used instead, fastened through the wall studs. Mirrors mounted to treated walls with clips or channel should be stabilized to prevent “rocking” of the glass within the channel and between the mirror and the wall by using folded cardboard, double-faced foam tape or tightly mounted side clips.
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Walls with loose plaster: Use clips and/or mirror channel fastened through the wall studs. Mastic will not stick to loose plaster, and the plaster can come loose from the wall even if used in a seemingly solid location.
Uneven walls: Mastic is recommended on uneven walls, in conjunction with clips, channel or other supporting medium. Mastic can help to level uneven wall applications. When mounting any number of mirrors side-by-side on uneven walls, it is recommended that the most level wall section be covered first as a guide for the pitch and angle of the other pieces. Use a brightly colored line level string set parallel to the mirrored wall, and set level from left to right as far from the mirrored wall as possible to use as a guide when installing successive mirrors. Each successive piece of mirror is to be installed in alignment with the previous. When viewing from a distance, the bright colored line in the reflection should appear as straight as possible from any angle or height viewed. Walls that are wavy or very badly out of even will require a “skeleton” back made of vertically mounted wood strips fastened directly to the walls to compensate for low areas. Screws used to fasten these strips must be countersunk into the wood preventing contact with the later installed glass.
Mirror fastening Mediums:
Mirror Channel - Mirror Channel or sometimes referred to mirror “J” channel forms a continuous line of support to the bottom edge of the mirror and serves to hold and stabilize the top edge of the mirror. Channel should be anchored securely to the wall in each stud along the line of the mirror to support the weight of the glass. In the bottom channel, the glass should be rested upon setting blocks at an interval of every 16 to 20 inches to defer vibration and friction between the metal and the glass. Mastic should also be used in larger mirror applications to stabilize the mirror and prevent “rocking” of the glass within the channel and between the mirror and the wall.
Mirror Clips – Mirror Clips function much the same as the above mentioned Mirror Channel, except that clips will only support the mirror at each point of installation. Mirror clips can be made of metal or plastic, and respective installation instructions provided with each should be carefully followed. Metal clips generally will support mirror at no less than 48 inches of spacing between. Exceeding this spacing will risk failure of the clip and the potential danger of the mirror falling due to the weight of the glass. Plastic clips generally should not be spaced more than 30 inches apart. As with the mirror channel, metal clips need vibration and friction protection. Metal clips should be used in conjunction with either a setting block or cardboard at the bottom. Mastic is also recommended in larger applications.
Mirror Mastic - Mastic can be obtained in cauling tube, sausage packs and individual "dots" that require no tools and no cleanup. Mirror mastic is a specially formulated adhesive designed for superior holding strength while free of chemical agents found in other adhesives that will damage the reflective mirror backing. Though methods vary, mirror mastic is typically applied in spots distributed evenly to represent one spot for every four to six square feet of glass depending on the application. Mastic is applied directly to the wall medium prior to setting the glass. Mastic is not recommended for walls with wallpaper, paneling or other treated wall mediums. Mastic is often used in conjunction with other fastening mediums for greater support.
Rosettes – These are the least-recommended fasteners but many older mirrors are mounted in this way. This practice is necessary when matching an existing style and is therefore explained. Holes must be drilled into the mirror, at no less than 4 inches from any edge, and at no further distance than 36 inches apart. In many cases, a thin plywood backing is mounted to the wall in advance to provide secure anchoring for each screw and to allow for easier wall leveling. Rosettes are not recommended for use in high-rise applications or in areas of seismic activity. Holes drilled through glass severely weaken the glass in the event of structural vibration and shift, prone to causing breakage of the glass. Mastic is often used for additional support, and any wood backing should be treated with a primer to prevent oils and sap from the wood from making contact with the mirror backing. Also, do not over-tighten screws as this will break the mirror very easily.
Do not attempt installing glass mirror on a ceiling surface using any of these methods! Consult a professional when attempting any glass or mirror installation where glass will be suspended above people or animals that could be harmed from falling glass.
