And here:

Also, I've noticed the silicone adhesive around the sink area turns milky white/translucent when wet. Is this normal? What is this a sign of? I've searched the internet, and can't find what this may be a symptom of. And I don't know what brand of silicone was used. Thanks in advance for any advice.

"Should I insist that they scrape out the initial seal and redo?"

javiwa:

No. You should insist that they remove the sink completely so that you can watch them remove the previous caulk from the sink flange and stone, apply 100% silicone between the flange and stone, mechanically fasten the sink, then wipe away the excess.

Silicone performs as a gasket, not as an adhesive.

If your stone has been reinforced with steel instead of stainless or fiberglas and the reinforcement is bedded in polyester instead of epoxy, a leaking sink can have catastrophic consequences eventually. This is nothing to fool with.

The worse part of this is that it's a classic hack alarm. Any fabricator that would leave a sink looking like this needs to have his entire job inspected by someone who knows what to look for. I would die of embarrassment if this were a picture of my work.

This post was edited by Trebruchet on Tue, Jan 20, 15 at 15:56

Thanks as always, Treb, for your advice. It looks like they used a black epoxy to 'glue' the sink to the granite (see pic ... black stuff oozing out between sink flange and granite?), and were indeed intending on using the silicone as a gasket -- however poorly the latter was done. Miserable execution aside, I assume it's OK to use the black glue.

Mechanical support: As seen in the pics, they've used 4 pieces of 1-1/2 x 8" plywood, screwed the bottoms into the cabinet walls, with the tops abutting the underside of the sink flange. They said they've done this for years and never had a sink fail. Is this not adequate?

Like so many others who frequent this forum, I'm suffering from a major case of subcontractor fatigue. Thanks so much for your guidance...it'll help me muster up enough energy to tell them they need to remove the entire countertop and install it properly.

Apologies for not properly embedding the pics within my post.

Here's a view of the right/underside of the cabinet space and bottom of sink.

And, finally, a shot from underneath the cabinet. Mine is a double bowl SS sink -- installer says they use this same plywood strip support method for heavier, cast iron sinks, and they work fine.

Oh I would be incredibly pissed that they screwed plywood into my new cabinets like that :o

SmileyGirl -- In the grand scheme of things, that wasn't even on my radar (which gives you an idea of how badly things have gone!). I guess if this method holds the sink up, that's all I need. Big IF! (While poking around, I noticed that one of the four strips wasn't actually touching/supporting the sink flange up top.) I still plan on installing a HUSH per Trebuchet's past recommendations. I know this is something the installer should be doing, but it's very hard to argue with these guys who generally take a "we'll have to agree to disagree" attitude.

Agree to disagree on your withholding final payment.

The drywall screws they're using for sink support have little strength in shear.

Drywall screws are designed to hold drywall to a wall, not support a sink, period. Treb is 100% correct and I also would be concerned about the balance of the install with the hatchet job they did on just this.

Thanks so much, Millworkman. It just dawned on me that: 1) they screwed the front plywood support strip onto the cabinet stile (frame piece, right?), which isn't meant to be load bearing, and 2) the vertical gap (1/8" in some spots) in the silicone around the granite-to-flange perimeter means the sink was never firmly in place; i.e., it 'dropped' very soon after installation.

The sink flange should sit flush against the granite underside, all the way around, correct?

"The sink flange should sit flush against the granite underside, all the way around, correct?"

Correct.

I install a Hercules Universal Sink Harness a bit differently than the manufacturer recommends. I prep for the harness, then slip a pipe clamp through a 2x4 with a hole in it that bridges the sink opening, then through the drain hole. Now I can draw the sink tightly to the bottom of the granite while adjusting for a perfect reveal. I install the HUSH and remove the clamp(s).

The current supports are all triangulated out from the vertical surface, at their tops (at the bottom where they are screwed to the cabinet wall, they touch the wall, but at the top there is a significant gap between the cabinet wall and the piece of ply). When the sink is weighted from being filled, etc., it is pulling the supports down. Instead of the supports staying in the same position, their gaps at the top are stretching, dropping the sink down and causing the caulk to pop open at the seam. It's an inherently flawed design for support, due to physics.

Treb - I don't think forethought is in this company's skill set...as has become agonizingly apparent.

Beautybutdebtfree - thanks for putting into such specific terms what's at play here. These guys obviously don't see a flaw in their design ("ma'am, we've been doing it this way for over 20 years" -- if I hear that ONE more time!), and I'm sure any mention of triangulation and physics will have them cockeyed. o_O

Oh I would be incredibly pissed that they screwed plywood into my new cabinets like that :o