Realistic stairwell

Hi, guys. I was building realistic scene from reference and got some questions:

I tried rendering in layers and for some reasons black seams between walls and beams appeared (they are in different layers). How to make a smoother transition?

How to recreate that light gradient in the background, like on the granite block? The yard on reference overall seems more saturated but when I add hue/saturation node and add some it still looks unnatural.

Should I add grey plane with lowered alpha in front of the window to make that grey tint on the left window, or there are some different methods?

And the last one: am I right that the main difference is lighting?

Why the layers? This doesn’t really look like the kind of scene where that would bring an advantage. Anyway, there is a proper way to do layers so the lighting still matches (using “holdout” and “indirect only”) and things should line up properly if it’s respected.

It would work, though it could also be done in the material, using a mix shader to blend between glass and translucent BSDF.

nice job so far. Try to use a roughness texture on the windows or lower the roughness a bit (make it less transparent basically) - may help. And desaturate the tree. And I think you may used a noise for the floor roughness - there a proper floor smudge/stain roughness texture would suit better