Hi, thank you for your inquiry! It has an interior dims of about 20" Depth x 84" width. Please note, the dimension may vary as its a plush cushion, but that is average.

This is a more sink into type of sofa and based In my experience most taller people find the sofa style with a higher back support more comfortable, but if they love the the Roche series they typically get an ottoman and the style of sitting is not bolt upright but slouched with feet out.

Underneath, you will find a stainless steel metal frame and a series of inner woven webbing spring straps support system running from north/south and east/west that adds support to the seat cushion as well as bounce since the lack of give wears out the cushion quickly and makes for a flat uncomfortable seating experience.

Hope this helps!

Thank you so much for the information! It is helpful in that I now know that this may not be the right sofa for me and my need for excellent lumbar support. do you sell other styles that have a more upright seat and offer better back support?

Here a few options:

[Woodrow Style[(https://www.houzz.com/products/woodrow-midcentury-modern-box-sofa-seat-black-base-walnut-prvw-vr~86808697?lid=67398362)

[Woodrow Neo[(https://www.houzz.com/products/kardiel-woodrow-neo-classic-midcentury-modern-sofa-aniline-leather-walnut-blac-prvw-vr~121623325?lid=91170414)

[Woodrow Lush[(https://www.houzz.com/products/kardiel-woodrow-lush-midcentury-modern-sofa-aniline-leather-walnut-brown-prvw-vr~121620566?lid=91168186)

[Jackie Sofa[(https://www.houzz.com/products/jackie-midcentury-modern-classic-sofa-aniline-leather-black-prvw-vr~24980903?lid=12833529)