Floating shelves in a corner or niche
No matter whether you’re dealing with new or old construction, walls are almost never straight or square enough to install woodwork without at least a little trimming. On a floating shelf installation, usually only one scribe line is needed which can be easily made with a compass. Occasionally, the job is to install a shelf into a corner or alcove so the shelf will abut walls on 2 or 3 sides. In that case it is impossible to hold the shelf up to the wall to draw a scribe line.
An accurate template can be made using 2″-3″ rips of thin plywood and a hot glue gun. The template then can be removed and laid on top of the shelf to trim to size. This technique is common practice for stone countertop fabricators, though it works very well for anything where a good fit is desired.
Trimming much more than 3/16″ from the back edge can affect the fit of the bracket.
If the wall corners are and square and straight you could order 1/16″- 1/8″ undersize and attempt to fit without trimming. For a tight fit on walls with more personality, you can choose to order 1/8″ – 1/4″ oversize so you may trim to size with a belt sander. You may also specify in the order notes “Loose cleat one end” or “Loose cleat both ends” for no additional charge we will prepare the shelves as such which can help simplify this type of installation.