Laid down but holding up

Two words than I never would've identified as cognates: joist and gîte. Both go back to giste, feminine past participle of Old French gesir (from Latin iacēre "to lie down") and thus can be glossed respectively as "a thing laid down" and "a place of lying down". The change of vowel in Middle English has never been explained, but is shared by the words hoist and foist. The other thing I learned from researching the etymology is that the form joice goes back much further than I suspected. Far from being a recent innovation, it's attested already in the 15th century.

The reason I'm thinking about joists again is that I'm reading Balzac and he begins his novella La Maison du chat-qui-pelote with a description of the eponymous house that includes an enumeration of many of its architectural elements, solives or "joists" prominent among them. My Cajun French materials actually list two terms for joists: soliveau for "ceiling joice" [sic] and lamboune for "floor joice". The latter is a variant of SF lambourde with basically the same meaning, i.e. a horizontal piece of wood meant to support a floor. Larousse gives the additional translations of "wall plate" and "backing strip", i.e. a piece of wood placed atop a joist in order to support timber framing.

This is why reading anything nineteenth century is apt to take me a while. So much unfamiliar vocabulary, and looking for English equivalents ends up becoming a mini research project. I try to ignore as much as I can so as not to get bogged down, but what am I reading these works for if not the colourtext?