Hi -
The depth of the built in bench is affected by the design of the cushions and the back - straight, sloped, thickness of bolster...
This bench is 30" deep. The seat itself is 22". The back is sloped at a 10 degree angle and has a wide top ( you cannot see it in this shot) so that it becomes the window sill and a continuous shelf for tea cups, wine glasses... as it goes along the wall. It is 8" at it's widest (from the back of the shelf as it touches the wall to the seat platform itself). The back cushions sit inside the 22" dimension. This makes the seat really comfortable to sit on sideways -- my favorite reading position - but requires a back cushion when you sit on it with your feet on the ground. For a bigger person, with longer legs ( I am just shy of 5' -4") no back cushion is needed.
Hope this helps.
cathy

Nice!!

What is the height of this bench from the floor, thickness and material? Thanks.

Hi
The bench is poured in place concrete and
becomes the hearth in front of the fireplace
as it is non-combustible. The leading edge you
can see is 4" thick and tapers down and back to a height
of 4" when it reaches the building wall.
To the left of the fireplace the "seat" continues
to the outside where it becomes an outdoor seat.
Thanks for the question.
Cathy