If you have instructions and you are questioning them, ask whoever provided the instructions to explain. While 4 screws will keep it in place if they are into something solid, it's possible that, with such a large piece of stainless, you could get oil-canning or bulging, especially on lighter gauge panels. If you also use construction adhesive, it improves the chances of it staying flat.

mudworm:

I'm with you on this one. Even if you screw it only and it oil-cans, so what? It's an easy do-over. Less is more when it comes to adhesives.

What does "oil-can" mean in this context?

With only four screws in the outside edges I would expect it to bow out in the middle.

As much as I hate to glue it down, I'd hate to see it flex (bow out) due to heat. Okay, with reluctance, I will break out the glue gun. Thanks for the input!

linelle-
Flat, sheet metal panels are never completely flat due to stresses within the metal, and from fabrication and installation. This can result in a noticeable bulging or waviness, and is more apparent on thin gauge materials and shiny surfaces. This is called "oil-canning" because the appearance is reminiscent of the slightly convex metal plate you pressed on to force the oil out of old oiling cans.

In addition to the characteristics of the panel itself, you can also get distortion if fasteners are driven in too tightly or if the panel is held in place with fasteners that do not allow the panel to move when it thermally expands or contracts -- as may happen with a backsplash that is exposed to heat from a stove.

If I were doing this install, I would run a couple of beads of adhesive across the center part of this panel and make sure the screw holes were oversized. That's just me...opinions may vary.

mudworm-
You don't need to overdo it. I think if you ran two lines of adhesive from top to bottom, dividing the panel into equal thirds, that might be enough. If the edges have all been turned over to strengthen them, then you might not need construction adhesive all around the perimeter...maybe just a single glob at the center of each edge. Good luck.

kudzu9, thanks for the explanation. I kinda figured it could distort with heat, etc., but didn't know it was called that.

"What does "oil-can" mean in this context?"

linelle:

I'm giving away my age here. My generation got the last of the real cans that oil came in. They switched to cardboard cans then to the plastic jugs we have now.

If you opened an oil can, especially without a "breather" hole at the opposite end, and poured the oil in your car's crankcase, the metal sides of the can would distort, hence the term. I got quite a shock looking up oil canning slang; it's apparently gotten quite a naughty connotation now days.

Here is a link that might be useful: Safe for work

mudworm:

If you decide to adhere the steel, I'd use a J-roller to get it good and flat:

Here is a link that might be useful: J-roller

Along with the J-Roller that Treb suggests, I would use an adhesive that can be troweled on with a notched tooth trowel, the same as one would with thin set, or vinyl flooring. It's hard to control the thickness and evenness with construction adhesive out of a caulking gun.
Any small lump or void will show through on the stainless and not look good and dead flat. Chris

edit to add: Or you could use a contact cement, as one would with laminate, but you better get it in the right spot the first time! ;)

This post was edited by ctycdm on Sat, Dec 6, 14 at 18:28

Treb, I suspect your generation is the same as mine. :p

mudworm-
Well, you're getting quite a range of opinion here, from don't use adhesive, to adhere the crap out of it. I'm somewhere in the middle: I think you can keep it pretty flat with a modest application of adhesive. I don't think that uneven application of adhesive will telegraph through the stainless steel. It might mean that some spots are less well adhered than others, but a highly uniform application of adhesive is not, in my opinion, a critical issue.

I agree with everything ctycdm said.

Piggy backing here:

What type of adhesive would you use to attache 24 gauge stainless steel sheeting (24"x30") to painted drywall?

Thanks again all for the replies. Things did not work out as planned, but maybe it's for the better. The helper showed up late, so I tried to look at the task myself. Decided to cut the caulking out between the wall and the countertop behind the cooktop. It allowed me to insert the backsplash downward enough for me to muscle the entire backsplash in place from under the hood. I preemptively shaved some drywall off where the gap is smaller than the thickness. Glad that I did because although I did it with the intention of trying out/dry fitting, I ended up having a hell of a time to back it out. Actually, it was so hard that I gave up. So, I simply brought the top forward to give me enough room to squeeze some adhesive in. Due to the awkward access, I just did snake pattern. BTW, the bottom two screw holes are behind the countertop and not accessible. The top two screw holes are so close to the hood and cabinets that I simply cannot go straight in. And when I tried, they were not hitting studs anyway, and I can't get the drywall anchor in. So, I'm mostly relying on the adhesive now to hold the backsplash. That's it. No removal in the future!

When the helper finally arrived, he was surprised to see that I already finished installing the backsplash.

Our contractor, who believes that any job worth doing is worth OVER-doing, used a bunch of liquid nail behind our splash, then anchored with boards across to hold for 24 hours. It's awesome, but I hope that I will not be the one who tries to remove it someday. Might as well take the wall down.