I'm planning to wall-mount a vintage 'Standard' victorian cast iron sink similar to the one in this question: Antique Cast Iron Sink Wall Mounting Support and Weight Issues?. That sink has two bolt points high on the sink through the porcelain; this sink has two bolt points / mounting tabs low on the sink.
There is a vertical stud centered exactly where I'd like to hang the sink. The wall is completely open in this area, so horizontal studs can easily be added.
There are 4 mounting tabs and brackets. Two on the rear against the wall, and one on each side. Ideally, I would like to mount the sink using only the two rear tabs bolted to the wall.
The standard cast iron brackets available for vintage sinks do not seem designed for this sink's brackets. The pockets are not deep enough for the tabs on my sink, the holes do not align, etc.
My initial thought is to use two heavy duty lag screws + washers through the rear tabs into horizontal studs in the wall. However, due to the geometry of this sink, it seems like that might not work. The tabs are low on the sink, not high near the top lip. And there is no lower structure below that point touching the wall to resist a downward force against the front lip.
This would seem to make the sink top heavy, prone to tipping forward either due to the weight of the sink or from someone putting weight on the front lip.
But perhaps I'm underestimating the strength of lag screws?
The other Issue I foresee is the "lip" that pushes the very top of the sink away from the wall. My solution would be to mount a 2×4 or similar piece of wood to the horizontal mounting studs, pushing the bolt locations away from the wall enough to clear the lip. But I do not want a 2×4 visible on the wall behind my sink, and I'm worried that if I "hide" a small piece of wood completely behind the sink that the bolts will not have enough spacing to the edge of the 2×4 (if that makes sense). Would something like a thick metal washer make more sense than wood?
Are two lag screws a viable way to mount this sink? If not, how should I mount it?
Best Answer
I am certain that if you mount that sink to the wall using only the two holes in the tabs, no matter how strong the mounting screws nor how hard the backing, the cast iron tabs will snap off.
In the worst case, the tabs will hold the sink in place for days or even weeks, then break suddenly when you are barefoot in your underwear and the sink is full of soapy water and a wet cat.
Don't even think about using this exquisite antique until you have figured out how to construct supports between the front mounts and the wall.
Other than the thickness of the backing board, you have a lot of freedom to determine dimensions. The backing board should extend downward as far as conveniently possible to spread the levering force. Using the backing board also allows you to position the sink without regard to the wall studs.
The screws and bolts that pass through the sink should be as large as will fit thru the holes, not only for strength but to avoid lateral motion.
Here is a rough sketch of a possible installation: