Hair Covering: Intimacy

it says in seforim that the walls of the house should not see a woman's hair. is this shayach when being intimate with her husband, if the husband wants?

Shalom! 

Thank you for your question. 

Please see the Biur Halacha siman 75 starting מחוץ לצמתן what the Chafets Chaim writes in the name of the Zohar on the importance of covering one's hair even when alone at home.

We also find in the Talmud, “Kimchis had seven sons, and each one of them served as Kohen Gadol. The sages asked her, ‘What did you do to merit this great honor?’ She replied, ‘I never allowed the beams of my house see my uncovered hair.’” 

Wishing you all the best.